Where Is It? What Is It? Why Can’t We See It? Dark Matter & Dark Energy Explained (Well, Sort Of).

Posted on September 25, 2026 by Mal Andrews

And just like that, another Friday has appeared from nowhere. This week folks, I’m going to do a bit of a follow up on last week’s article. If the measurement problem is the biggest mystery in quantum physics, then Dark Matter and Dark Energy are the biggest mysteries in cosmology. Together they make up about 95% of the Universe, yet we still do not know exactly what either of them is. Ordinary matter, meaning stars, planets, gas, dust, trees, people and everything you’ve ever touched, accounts for only about 5% of the cosmos. Dark Matter contributes roughly 27%, while Dark Energy contributes roughly 68%.

So, are you ready? Hang on to your hats, it’s time for us to dive into another rabbit hole of truly cosmic proportions!

And we’ll start with a universe that really doesn’t add up, and as is obligatory, an analogy. Imagine you’re sat staring out of a window watching leaves swirling around in a strong wind. You can’t see the wind itself, but you know it’s there because of what it does to the leaves, and Dark Matter and Dark Energy are similar. We don’t directly see them, however, we infer their existence because of their effects on things we can observe. But that’s where the similarities end, as where Dark Matter pulls, Dark Energy pushes. One helps gravity hold the Universe together, while the other seems to be trying it’s very best to tear it apart.

The story begins in the 1930s, when Dark Matter was discovered. Swiss astronomer Fritz Zwicky was studying the Coma Cluster, a truly huge collection of galaxies, within the constellation Coma Berenices. He calculated how much visible matter the cluster contained and compared it to how fast the galaxies were moving. The numbers didn’t make sense. The galaxies were moving so fast that the cluster should have flown apart long ago as there wasn’t enough visible mass to provide the necessary gravitational glue. He proposed there must be a large amount of invisible matter. He called it dunkle Materie or “Dark Matter.”

At the time, and for many years after, most astronomers ignored the idea, until Vera Rubin discovered something even stranger in the 1970s. Galaxies had a rotation problem.

According to Newtonian gravity, stars near the centre of a galaxy should orbit quickly, and stars far from the centre should orbit more slowly, and this is exactly what happens in our Solar System. Mercury, which is very close to the sun, races around it, while Neptune, which is nearly three billion miles from the sun, crawls along in its distant orbit. But galaxies simply appeared to be refusing to obey these rules.

Rubin found that stars far from galactic centres were moving almost as fast as stars much closer in. It was as if galaxies were embedded in enormous invisible halos containing far more mass than all their stars combined, and this discovery became one of the strongest pieces of evidence for Dark Matter.

Which leads us to the question of how do we actually know Dark Matter exists?

And to answer this question, scientists actually have several independent lines of evidence. The first of which is that galaxy rotation actually curves (let me know if I’m overusing the word actually, as somebody actually pointed out to me, I actually do. Apparently). Stars move too quickly to be held by visible matter alone. Secondly, galaxies gather in clusters, which remain gravitationally bound despite insufficient signs of visible mass. Thirdly we have gravitational lensing, something else I’ve touched upon in previous articles. Einstein’s General Relativity says mass bends spacetime, that is, when light passes a massive object, it bends. Astronomers observe lensing effects that require far more mass than visible matter can supply, and it is this that allows scientists to map Dark Matter distribution directly. And lastly, we have the Cosmic Web, which shows us that on the largest scales, galaxies form immense filaments and clusters. Additionally, computer simulations can only reproduce the Universe we actually observe when large amounts of Dark Matter are included.

So, what is Dark Matter? And just like last week with the Measurement Problem, the honest answer is…

…Nobody knows.

There are some things we do know though, and they are that Dark Matter has mass, produces gravity, does not emit light, does not reflect light, and barely interacts with ordinary matter.

So, in a sense, Dark Matter is almost ghost-like as it can pass through ordinary matter seemingly without notice.

Right now, there are several ideas competing with each other as to why, and for decades the favourite candidate was WIMPs.

“WIMPs” are Weakly Interacting Massive Particles, and huge underground detectors have been searching for them, and so far, as tends to happen with the science of the cosmos, nothing definitive has turned up.

We also have Axions, which are extremely teeny-weeny hypothetical particles, and although they are hypothetical, axions remain a popular possibility with scientists. As do sterile neutrinos, which are a heavier cousin of familiar neutrinos that barely interact with anything. Or it could be something completely different and far stranger than our current theories. All we know for sure is that we don’t know what it is, and at present, Dark Matter remains unidentified.

There are some other ideas out there, some of which are pretty wild. Could gravity and everything we know and understand about it be wrong? What If Dark Matter doesn’t exist at all? Maybe gravity behaves differently on enormous cosmic scales?

The best-known attempt at describing this is another scientific theory known as MOND, which stands for Modified Newtonian Dynamics. (another article for later, methinks). And although MOND can explain some weird galactic behaviour, it is Dark Matter that generally provides a better explanation across many observations, including galaxy clusters and cosmological measurements. And this is why most cosmologists therefore regard Dark Matter as the leading explanation.

OK, if Dark Matter is pretty weird, Dark Energy is downright bizarre, and its discovery completely shocked the scientific community, as for most of the twentieth century, astronomers assumed gravity would gradually slow the Universe’s expansion. Which when you think about gravity seems obvious. Gravity attracts. Everything should slowly pull everything else back together. Right?

Well, unfortunately not. Back in the late 1990s, astronomers measured distant exploding stars called Type Ia supernovae and the result was astonishing, and it showed us that the Universe wasn’t slowing down. It was accelerating. Some mysterious phenomenon was overcoming gravity on the largest scales, and that phenomenon became known as Dark Energy. Cool, yeah!

That leads us to the next obvious question, what exactly does Dark Energy do? And, you’ve guessed it, it’s analogy time!

Imagine throwing a ball upward and now imagine the ball speeds up instead of slowing down, and that is essentially what the Universe is doing, as galaxies, on average, are becoming separated faster and faster over time, and Dark Energy appears responsible for that acceleration.

So, that sort of answers what it does, but what actually is Dark Energy? And you’ve guessed it…

… Nobody knows.

Although several possibilities do indeed exist.

It could be vacuum energy, where empty space may not be empty, as quantum physics says that even a perfect vacuum is seething with fluctuating energy. And Einstein’s equations permit vacuum energy to act as a repulsive force.

This explanation is currently the leading candidate, but, as always when the teeny tiny stuff becomes involved, there is a problem. Theoretical calculations predict vastly more vacuum energy than astronomers observe. This mismatch is one of the largest known discrepancies in physics.

Then we have Einstein’s cosmological constant. He added a term, Λ (Lambda), to General Relativity, and many cosmologists today model Dark Energy as this cosmological constant as it behaves like a fixed energy density which is present throughout space.

Perhaps Dark Energy is a dynamic field that evolves with time, and unlike a cosmological constant, it could strengthen or weaken as the Universe ages.

At this time, however, there is no evidence that currently favours this idea over simpler models.

That’s not all. As dark as this is, there are even stranger things afoot. Dark Matter becomes diluted as the Universe expands, and Dark Energy apparently doesn’t. As space grows, more space contains more Dark Energy, meaning that Dark Energy ultimately dominates the Universe’s future evolution.

So, with all that conflict, confusion and unknowns, what does all this actually mean for the future?

Well, we know that current observations suggest that the Universe will continue expanding, as expansion continues accelerating, distant galaxies will drift beyond visibility, and the cosmos will ultimately grow increasingly dark and cold, leading to what is known as the Heat Death or Big Freeze (pretty sure I’ve mentioned this in a previous article), trillions upon trillions of years from now, stars will eventually burn out and galaxies will grow isolated in an immense ever expanding darkness.

So why can’t we see Dark Matter and Dark Energy? The answer is actually quite simple as they don’t interact with light. No absorbing it, no emitting it, no reflecting it, nothing for a telescope to actually catch. We only know they’re there because of what they do to everything around them.

And what they do couldn’t be more different. Dark Matter shapes galaxies and galaxy clusters from the inside, holding cosmic structure together like an invisible scaffold. Dark Energy, on the other hand, barely registers on local scales at all. Our solar system, our galaxy, even our galactic neighbourhood, are all gravitationally bound tightly enough that it can’t get a grip. It only shows its hand once you zoom out to the vast, mostly empty stretches between galaxies, and that is where it dominates completely.

There is a search going on as I write this as modern observatories are attempting to solve these mysteries. One of the most important is the European Space Agency’s Euclid mission, launched in 2023. It is creating a massive three-dimensional map of billions of galaxies to investigate the nature of Dark Matter and Dark Energy and how cosmic structure evolved over time. And alongside Euclid, projects such as the Vera Rubin Observatory, James Webb Space Telescope, and the upcoming Nancy Grace Roman Space Telescope are expected to provide unprecedented data.

There is quite an astonishing bottom line to all this, as the most remarkable fact is not that Dark Matter and Dark Energy are mysterious, it’s that everything familiar is the exception, not the rule. All stars. All planets. All oceans. All people. Every great civilisation. Every work of art. Every living thing that has ever existed! Together all that and more only makes up about 5% of reality. The remaining 95% of the Universe consists of things we can detect only indirectly and do not yet fully understand. So, in other words, humanity has become extraordinarily good at studying the cosmos, only to discover that most of it is still hidden from view. And that, folks, may turn out to be one of the greatest scientific surprises of all time!

Nobody Knows Why Looking Changes Everything – Welcome to the Measurement Problem!

Posted on September 18, 2026 by Mal Andrews

Hello everyone! This week I’m going to try and answer one of the questions I’ve received regarding my piece on the Block Universe. And that is, why does observing a quantum system change it. It is a very good question, and it’s an extremely tricky one to answer as it’s one of those aspects of the teeny tiny stuff that took me a while to wrap my head around.

So what is the answer? Why does observing a quantum system change it? And the answer is…

Well, actually, nobody really knows why.

It is, in fact, one of the deepest questions in physics. And nearly a century after quantum mechanics was developed, nobody knows with certainty why measurement produces definite outcomes. The mathematics predicts experimental results with extraordinary accuracy, but what the mathematics means is still debated.

To take a closer look, imagine you’re in a casino where every roulette wheel is somehow landing on every number at once. Not one result. All of them. Red, black, odd, even, 17, 32, 8, 0. Every possibility exists simultaneously in a cloud of uncertainty. You walk over, look at the wheel, and suddenly there’s only one answer staring back at you. Red 17. One outcome. One reality. The mystery at the heart of quantum physics is that nature seems to work a little like this, and nobody is entirely sure why.

For centuries, scientists imagined the Universe as a giant clockwork machine. Objects had definite properties whether anyone looked at them or not. A football occupied a particular position in the air or on the field, a cannonball travelled along a specific trajectory, and a cat was either asleep or awake.

Then quantum mechanics came along, yet again, and politely informed us that, at the smallest scales, reality appears to be playing by very different rules indeed.

According to quantum theory, particles such as electrons are described by something called a wave function. Rather than telling us exactly where a particle is, the wave function describes all the possible places it could be found. Before measurement, an electron can exist in what physicists call a superposition, which is a state containing multiple possibilities at the same time.

Imagine flipping a coin spinning in the air. While it’s rotating, you can’t honestly call it heads or tails. In a loose sense, it represents both possibilities. The quantum world takes that idea far beyond anything we’re used to. Before measurement, particles don’t merely hide their properties. According to the mathematics, the multiple possibilities genuinely matter.

The famous double-slit experiment, which I mentioned in my Five Things… article, reveals this bizarre behaviour in dramatic fashion. Fire electrons through two narrow slits and they create an interference pattern, exactly what you would expect from waves passing through both openings simultaneously. Somehow, each electron behaves as though it explores multiple possible paths at once. Yet the moment scientists place detectors at the slits to discover which route the electron takes, the interference pattern disappears. Suddenly the electrons behave like ordinary particles. It’s as though nature says, “If you’re not asking, I’ll keep my options open. If you are asking though, I’ll commit to an answer.”

This puzzle sits at the centre of what physicists call the Measurement Problem.

The equations of quantum mechanics describe the wave function evolving smoothly and predictably through time. Left undisturbed, the mathematics allows all these possibilities to continue existing in superposition. Yet whenever a measurement is performed, we observe only one result. Not many. Not a mixture. Just one. The electron appears here. The detector clicks. The cat is alive or dead. The equations predict probabilities perfectly, yet they don’t clearly explain why one specific reality emerges from many possibilities.

Popular science often makes this sound even stranger by claiming that consciousness creates reality. As catchy a headline as this is, most modern physicists don’t believe the human mind is the crucial ingredient. In quantum mechanics, “observation” doesn’t mean a conscious person staring at something. It means a physical interaction that extracts information. A detector can do it. A photon can do it. Even the environment can do it. This is the tricky bit, folks, and it’s the one that I wrestled with when first studying this stuff. Once you can get your head past a person looking at it as the observer, it really does make perfect sense, trust me!

That’s because obtaining information isn’t passive. To discover where an electron is, something must interact with it. Light must bounce off it, a detector must absorb it, or some other physical process must occur. At the quantum scale you cannot simply peek without participating. The act of learning something about the system inevitably becomes part of the system’s story. With me? Of course you are.

For decades this left physicists wondering why the weird quantum world of that pesky teeny tiny stuff doesn’t spill over into everyday life. If electrons can occupy multiple states at once, why can’t cats? Why don’t we see cars parked in several places simultaneously?

Which leads to something you will all be very familiar with, even if some of you struggle to understand it, and no discussion of the measurement problem would be complete without the most famous feline in science, Schrödinger’s Cat.

Are you ready? I’m going to attempt an explanation that hopefully makes sense. In 1935, physicist Erwin Schrödinger invented a deliberately ridiculous thought experiment to show how strange quantum mechanics becomes if you apply it to everyday objects. Imagine a cat sealed inside a box with a tiny amount of radioactive material, a detector, and a vial of poison. If the radioactive atom decays, the detector triggers and releases the poison. If the atom doesn’t decay, the cat lives.

According to quantum mechanics, before anyone opens the box, the atom exists in a superposition of both decayed and undecayed states. With me so far? Good. OK, if you follow the mathematics all the way through, the cat should also end up in a superposition of being both alive and dead at the same time. Schrödinger wasn’t suggesting that cats really exist as zombie-like half-alive creatures. It was quite the opposite. He had designed the experiment to highlight the apparent absurdity of extending quantum superpositions into the everyday world. Yet when the box is opened, nobody ever finds a cat that’s simultaneously alive and dead. They find one or the other. The actual question is: at what point did reality make up its mind? Was it when the atom decayed? When the detector clicked? Was it when the box was opened? Or did both outcomes somehow continue to exist? That deceptively simple question lies right at the heart of the measurement problem and continues to fuel debate among physicists nearly a century later.

This brings us to one of the most important advances in modern quantum theory, which is decoherence.

I could write a whole article on this, but in another attempt to keep it simple, this isn’t my analogy, but it is the most beautifully simplistic one I could find. Imagine dropping a single drop of blue food colouring into a glass of clear water. At first, the drop is obvious and distinct. But within moments the water molecules begin colliding with it. The blue colour spreads throughout the glass until the original blob is impossible to identify. The information about where it started hasn’t vanished. It’s just been dispersed among trillions of molecules.

And something remarkably similar appears to happen in the quantum world. A quantum system begins with delicate patterns of possibility that allow superpositions and interference to exist. But the system never remains perfectly isolated. Photons strike it. Air molecules collide with it. Heat radiates through it. The environment is constantly interacting with everything around it, and as this happens, information about the quantum state leaks into the surroundings and becomes distributed among enormous numbers of particles. The special quantum coherence that made the system behave in a wave-like manner effectively gets diluted into the environment.

The result is that quantum weirdness fades astonishingly quickly for large objects. Your coffee cup isn’t in two places at once because it’s interacting with countless particles every second. The environment is continually monitoring it, as it were. Quantum coherence becomes spread out so rapidly that classical reality emerges almost instantly.

For a while, many physicists hoped decoherence would completely solve the Measurement Problem, and although it solved a huge part of it, it didn’t solve all of it.

The food-colouring analogy helps explain why. Imagine the colouring spreading throughout the water. You’ve explained why the original neat drop is no longer visible. But you haven’t explained why you should focus on one particular blue molecule rather than another.

Likewise, decoherence explains why quantum superpositions stop being observable and why the world looks classical. What it doesn’t fully explain is why a specific outcome appears. It tells us why the roulette wheel no longer displays all possibilities simultaneously. It doesn’t completely explain why you experience red 17 instead of black 32.

This is why competing interpretations still exist. The Copenhagen interpretation accepts collapse as a fundamental part of nature. Many-Worlds suggests every outcome occurs and reality branches into multiple universes. Objective collapse theories propose that collapse is a real physical process waiting to be discovered. Bohmian mechanics argues that particles always possess definite properties guided by hidden quantum processes. All reproduce the experimental data, however, none of them have achieved any universal agreement.

And that’s what makes the measurement problem so extraordinary. Quantum mechanics may be the most successful scientific theory ever devised. It powers modern electronics, lasers, GPS corrections, MRI scanners and emerging quantum computers. Yet beneath its incredible success lies an unanswered question that goes right to the heart of reality itself.

When you look closely enough at nature, possibility seems to come before certainty, but how certainty finally emerges from possibility remains one of the deepest mysteries in all of science.

Phew. I made it! I hope that makes sense, as I stated at the beginning, it’s a very tricky question to answer, and there are so many different ways an attempt at answering it can be made. A bit like the subject matter itself, I guess!

The Block Universe: Is Time an Illusion? And Lunchtime Doubly So?

Posted on September 11, 2026 by Mal Andrews

A change of pace this week folks, let’s take a look at one of the more far-out theories that has come from Einstein’s theories. Have you ever woken up in the morning and wondered what actually happened to yesterday? Not what happened yesterday, but what happened to it now that it is over and in the past. If you haven’t, take a moment now and consider a simple question: Where is yesterday? Where did it go?

To the majority of us, the answer is instinctively simple. It has gone, it’s over, yesterday has vanished into the past, tomorrow has not yet arrived, and only the present moment is real, what we are doing in the now exists. This is a view that is so deeply woven into human experience that it feels beyond dispute. That there is no other way to answer that question. But, there is another theory, and it is one of the most intriguing ideas to emerge from modern physics, and this theory suggests that intuition may be wrong.

According to the Block Universe Theory, also known as Eternalism, the past has not actually disappeared, the future is not awaiting creation, and the present is not uniquely real. Instead, all moments in time, every heartbeat, every supernova, every historical event, and every future conversation, exist together within that vast four-dimensional structure we know as spacetime. If this is true, the universe is not a story being written as it expands and events unfold naturally. In actuality, it is a completed manuscript.

To understand the Block Universe, imagine a DVD containing your favourite movie. On that DVD, every scene exists simultaneously, the opening scene, the climax, and the ending are all physically present and the characters experience events in sequence, but the entire film already exists. Supporters of the Block Universe argue that reality may be similar. Rather than viewing reality as a three-dimensional universe moving through time, physicists describe the universe as a four-dimensional spacetime, where time is treated as another dimension alongside length, width, and height. In this picture, your birth exists, your current moment exists, and your future exists, all these events occupying different locations within spacetime itself, and the sensation time is flowing may simply be the way our consciousness experiences moving through this structure.

Now then, a common misconception is that the Block Universe somehow contradicts Einstein’s theories, whereas in reality, many physicists believe the idea arises naturally from relativity.

This is a principle known as the relativity of simultaneity. I’ve mentioned this in my Special Relativity article remember? It’s the throwing the ball on the moving train analogy. This is the core concept from that theory that states that whether two separate events happen at the same time depends on the observer’s point of view, that is, two events that look simultaneous to one person can happen at different times for another person in motion. Einstein’s Special Relativity shows that observers moving relative to one another can disagree about which distant events are occurring “right now.” There is no universal cosmic clock that defines a single objective present for the entire universe.

Let’s consider two observers moving differently through space. Now then, where one observer may regard two distant events as simultaneous, another observer may calculate that one event happened earlier than the other. Neither perspective is privileged as both are permitted by the laws of physics. However, this then creates a profound problem for the everyday notion of “the present.” If there is no universally agreed-upon present moment, then what exactly separates the real present from the unreal future?

Many philosophers and physicists argue that the simplest answer to this conundrum is that all moments exist equally, and that the distinction between past, present, and future becomes a matter of perspective rather than the fundamental reality.

Einstein himself famously remarked that the distinction between past, present, and future is “a stubbornly persistent illusion,” a statement often associated with block theory enthusiasts as an interpretation of spacetime. Importantly, though, Einstein’s equations do not explicitly state that the Block Universe is true. Rather, they describe spacetime in a way that many researchers believe is compatible with, and perhaps even suggestive of, a block-like reality

Now it’s time for the pesky teeny tiny stuff to make its appearance as quantum mechanics makes its entry, and as friendly as relativity may appear to the Block Universe, quantum mechanics brings with it complications.

Quantum theory describes a world fundamentally different from the clockwork universe envisioned by classical physics. We know, from my two-parter, that particles can exist in superpositions of states, where outcomes often appear probabilistic rather than predetermined. Entangled particles exhibit correlations that seem astonishingly non-local. With this in mind, quantum mechanics appears to threaten the entire Block Universe concept.

If the future already exists, how can quantum events be genuinely uncertain? And the answer to that question depends on which interpretation of quantum mechanics you adopt.

First off, we have the deterministic view, and that is that some interpretations, such as the Many-Worlds Interpretation, preserve a deterministic mathematical evolution of the quantum wave function. In these interpretations, reality may still be represented as a vast block-like structure, although it is one that is far stranger than originally imagined.

Next, we have the indeterministic view, which is that other interpretations treat quantum events as involving genuine randomness. Here the future may not be completely fixed until measurements occur, and some physicists see this as direct evidence against a fully formed Block Universe.

And finally, we have the current situation, which is that in actuality, there is no consensus as modern physics has not yet produced a universally accepted synthesis of quantum mechanics and general relativity. It is because of this that the relationship between quantum theory and the Block Universe remains an active area of investigation rather than a settled question.

So, in short, quantum mechanics does not definitively rule out the Block Universe, but it doesn’t conclusively prove it, either.

That leads us on to the problem of free will, and no consequence of the Block Universe generates more debate than its apparent attack on free will. If your future already exists, are your choices truly choices?

Let’s suppose that somewhere within the four-dimensional structure of spacetime there already exists a future version of you deciding whether to accept a job, move cities, or buy that really fast car you want.

Has this decision already been made? If you think about it, at first glance, the answer appears somewhat disturbing, and many critics argue that a Block Universe implies a fixed future and therefore eliminates genuine freedom. That is, if every event is already part of spacetime, then the sensation of choosing may merely be an experience within the block.

However, defenders of free will offer several responses.

Compatibilists argue that free will does not require the future to be open as a decision can still be free if it arises from your values, beliefs, reasoning, and desires, even if that decision is a permanent feature of spacetime. In this view, your future choice exists, but it is still your choice.

Another argument arises from the observer’s perspective. This is because while the future may exist, you don’t have access to it. From within time, uncertainty remains unavoidable, and you deliberate, and evaluate options, and make decisions exactly as before. The difference here is that the existence of future events in spacetime would not grant anyone knowledge of them.

Then we have the libertarian objections. Philosophers who believe genuine free will requires alternative possibilities often reject the Block Universe entirely. They argue that a future that already exists cannot be meaningfully changed and therefore cannot accommodate true freedom.

And like many of these conflicting theories, the debate remains very much unresolved.

One reason the Block Universe fascinates both scientists and science-fiction writers (I have just completed a novel using this very theory as the premise) is that it appears naturally compatible with some forms of time travel. If all moments exist, then travelling to another time may be conceptually similar to travelling to another place. And that is an excellent tool for writing into fiction as General Relativity contains solutions to Einstein’s equations that permit unusual spacetime geometries. Although whether such structures could exist physically obviously remains, like most things in this field, uncertain. That said, the Block Universe does not automatically enable time travel, but it provides a conceptual framework in which the idea becomes easier to imagine.

The Block Universe is not merely a theory about clocks and calendars. It is a new view of reality, as it challenges some of humanity’s most fundamental assumptions. Is time really flowing? Does the future already exist? Is consciousness responsible for our experience of temporal passage? Can free will survive in a universe where every moment is equally real? How does quantum uncertainty fit into the picture?

And once again, my faithful few, more than a century after Einstein revolutionised our understanding of space and time, these questions remain very much unanswered.

Perhaps time truly flows, and the future has yet to be written. Or perhaps, at this very moment, every chapter of your life already exists within an immense four-dimensional cosmic structure, not waiting to happen, but simply waiting to be experienced.

Newton’s Laws: The Three Rules That Keep the World Moving

Posted on September 5, 2026 by Mal Andrews

Another delay in posting, so apologies again, but at least I’m only a day late this time. Anyway, here it is, and this week I’m going to delve into the Laws of Sir Isaac Newton.

Whether you’re kicking a football, driving a car, or watching a rocket launch into space, you’re seeing Isaac Newton’s laws of motion in action. Just take a moment, and imagine you’re sitting on a bus, and the driver, without warning, suddenly slams on the brakes, and your body lurches forward. Why does that happen?

Or imagine a football soaring across the pitch after a powerful kick from Harry Kane has sent the ball screaming into the back of the net from 30 yards out. What is it that makes it speed up, slow down, and eventually stop?

And how does a rocket, weighing hundreds of tonnes, actually manage to leave Earth and get into space?

The answer to all of these questions, and many more, can be traced all the way back to three ideas developed by Sir Isaac Newton more than 300 years ago. Published in 1687, Newton’s laws of motion became the de-facto foundation of classical physics and at the same time transformed our understanding of how the universe actually works.

It is remarkable that these laws are simple enough to explain everyday events while being so powerful they can help send spacecraft into orbit.

Now my faithful few, it’s time to dive in and take a closer look.

Let’s start with the First Law and look at why things don’t like to change.

Newton’s First Law is often called the Law of Inertia, which in simple terms, says that things tend to keep doing whatever they’re already doing. An object sitting still wants to stay sitting still, and an object moving along, minding its own business as it travels in a straight line wants to keep moving along, minding its own business, travelling in that same direction at the same speed. It will only change speed or direction if some force acts upon it causing it to do so.

As obvious as this may sound now, at the time it was a revolutionary idea.

Before Newton came along, most folk believed that motion required a constant force, which, if you think about it, in everyday life seems true. Roll a ball across the floor and it eventually stops. Newton, however, realised the ball doesn’t stop because moving objects naturally come to rest. It stops because forces such as friction and air resistance are working against it and if you were to remove those forces the ball would keep rolling indefinitely, and that tendency to resist changes in motion is called inertia.

You experience inertia every day. It’s why passengers lean forward when they are traveling in a bus and the driver brakes suddenly. All their bodies are simply trying to do is continue moving at the speed they were already travelling.

Newton’s Second Law applies to what happens when you push things. We all know that objects don’t always trundle along, moving in the same way. They can speed up, they can slow down, and they tend to change direction all the time. This is where Newton’s Second Law comes in.

It explains the relationship between force, mass, and acceleration, and in its formulaic state it is usually written as F = ma. In other words, force equals mass multiplied by acceleration. The idea is straight forward enough, the harder you push something, the greater its acceleration is. But the heavier the object, the more force you’ll need to produce the same effect.

Imagine you are pushing an empty shopping trolley along the isles of your favourite supermarket. It moves easily (unless you’ve got the one with the dodgy wheel). Now fill it with your weekly shop and suddenly it takes much more effort to get it moving. The force you’re applying might be the same, but the mass has increased.

This beautiful law is one of the most useful tools in science and engineering as it helps designers calculate everything from the power of a car engine to the thrust needed for a rocket launch.

That takes us nicely onto Newton’s Third Law. And that is, every force has a partner in crime.

By now, you might be wondering how movement starts in the first place, and the third law explains this. And this is the famous saying you have heard many, many times before, as Newton said, “For every action, there is an equal and opposite reaction.” Put simply, this means that whenever one object pushes on another, the second object pushes back with exactly the same force in the opposite direction.

Let’s take something as simple as walking down the street as an example. Most of us simply assume that, when walking, they move forward because their legs push them ahead. But, this isn’t the case as what actually happens is way more interesting. As your foot pushes backward against the ground, the ground pushes forward against your foot, and that reaction force propels you forward. Exactly the same principle explains swimming. As you push water backward, the water pushes you forward. It also explains rocket launches. As engines expel hot gases downward, those gases push back on the rocket, which sends it upward, soaring into the sky and beyond.

Without Newton’s Third Law, space travel wouldn’t be possible.

If you’re looking for proof that Newton’s laws aren’t just dusty ideas from a physics textbook, look no further than Apollo 13.

In the 1995 film, Tom Hanks portrays astronaut Jim Lovell, commander of the ill-fated lunar mission that suffered a catastrophic explosion on its way to the Moon. At one point, with the spacecraft’s systems being shut down to conserve precious power, Lovell turns to his crew and says:

“We just put Sir Isaac Newton in the driver’s seat.”

It’s a great Hollywood line, but it’s memorable because of its roots in reality.

The real Apollo 13 mission faced a daunting physics problem. After the explosion, the crew had to nurse a crippled spacecraft home from hundreds of thousands of miles away, with power limited and most of the systems switched off, so they could no longer rely on their computers in the normal way. Instead, they had to trust in the laws of motion and gravity, Newton’s laws, to carry them around the Moon and safely back to Earth. Even seemingly harmless actions could become a problem. The crew were warned by Mission Control not to vent any waste from the spacecraft into space as this might create a small thrust, tiny enough that it could nudge them off course. In the vacuum of space, where there is no air resistance to slow things down, even tiny forces matter, and that is what Jim Lovell meant by “putting Newton in the driver’s seat.” The astronauts were placing their faith in the very laws Newton had described nearly three hundred years earlier.

The First Law kept the spacecraft moving along its path once it was set in motion, and the Second Law explained how small, carefully planned engine burns would alter their path when course corrections were needed. The Third Law explained why those engine burns worked at all, as gases expelled in one direction pushed the spacecraft in the opposite direction.

It’s one of those rare moments where science, history and popular culture intersect perfectly. At the height of the Space Age, surrounded by cutting-edge technology, three astronauts ultimately trusted one of the oldest and most fundamental ideas in physics. When everything else seemed uncertain, Sir Isaac Newton was still safely at the wheel.

As individually simple as Newton’s laws are, they produce a powerful picture.

The first tells us that motion doesn’t change without a force. The second tells us how much motion changes when a force is applied. The third explains where many of those forces come from in the first place.

Together, the three laws create a complete picture of how objects move, interact, and respond to the world around them. From bicycles and footballs to aircraft and planets, these three principles describe an astonishing range of motion.

More than three centuries after Newton wrote them down, they remain among the most important ideas in all of science.

So, the next time you’re on a bus and the driver brakes suddenly, or you’re at the footy and a screamer hits the back of the net, or you‘re watching Apollo 13 and Tom Hanks utters that famous line, you’ll be witnessing those three elegant laws at work.

Although the technology may change, the universe is still playing by Newton’s rules.

TIME IS NOT WHAT YOU THINK IT IS – The Day Einstein Destroyed Common Sense

Posted on August 31, 2026 by Mal Andrews

Hello everybody, apologies for the three-day wait for this one, I’ve been away with the family over the weekend, during which I have managed to properly injure my back. Despite the pain though, it’s time for another promised article, the one on Special Relativity, and for this one I’m going to start with a classic.

Imagine you’re sitting on a train moving smoothly through the countryside, and while you’re sitting you happen to pull out a tennis ball, you conveniently have with you, and toss it to a friend sitting opposite you. Everything feels normal, the ball travels over the table exactly as expected, and your friend catches it. Now imagine I am standing beside the tracks watching as you make the same throw as the train passes by me. To you, the ball moved at about 20 mph, however, to me, observing from outside, the ball moved at the train’s speed plus the speed of the throw.

For centuries, this simple idea seemed obvious, and it was the foundation of Isaac Newton’s view of the universe. Then, in 1905, a 26-year-old patent clerk named Albert Einstein published a paper that changed everything. In that paper, he came to a startling conclusion. Space and time are not fixed but actually bend to accommodate one unbreakable rule. And that rule is:

The speed of light is always the same.

You all know this, I’ve written about it plenty of times in my articles now, but at the time, this was revolutionary.

299,792,458 metres per second, which is around about 186,000 miles per second, fast enough to travel around the earth about 7 times in one second, and fast enough to reach the moon in about 1.3 seconds. What makes light particularly special though, is every observer measures it moving at exactly that speed, regardless of their own motion.

I know this sounds impossible but just suppose you are standing still and you are measuring a beam of light from a torch (flashlight to my American readers) and I come racing towards it at 99% of light speed. Common sense tells us that I should measure the light moving only a little faster than me, but I don’t. And neither do you. What we both actually measure is exactly the same speed. Nature is somehow protecting this value, but it’s doing it at a price. Reality itself must change.

The first casualty of this is time. Now then, Newton believed time flowed identically everywhere, however, Einstein discovered that time behaves more like an elastic material. That is, the faster you move, the slower your clock runs compared with someone standing still, and physicists call this time dilation.

Imagine two identical clocks. One of them is safe and sound on Earth, hanging on your kitchen wall while the other is flying through space at enormous speed. If you were to retrieve the travelling clock after its journey it would show that less time has elapsed than the one on your kitchen wall. It has literally experienced less time, not because it has malfunctioned, and not because of some kind of optical illusion. It is showing less time because time itself has passed more slowly for it.

There are tiny particles produced high in the Earth’s atmosphere called muons which without relativity should decay long before reaching the ground, but lots of them survive. Why do they survive? Because they travel near light speed, and their internal clocks run slower. Exactly as Einstein predicted.

On to the next question. If time can stretch, what about space? Well, it turns out space makes sacrifices as well, as an object moving rapidly relative to you becomes shorter in the direction of travel, and physicists call this Length Contraction.

Imagine a spacecraft that is 100 metres long while resting in its space port. After undocking and zooming off to Alpha Centauri, as it approaches light speed, a stationary observer sees it become shorter and shorter, while the crew onboard experience nothing unusual, as from their perspective, it is the rest of the universe that has changed. And this is one of relativity’s strangest lessons. There is no single universal viewpoint as different observers can measure different lengths and times and still all be correct.

Moving on, most people believe they know what “at the same time” means. Einstein showed that they don’t.

Imagine a train, again. There’s a massive thunderstorm raging overhead and bolts of lightning strike both ends simultaneously. To someone standing on the station platform, they would see both flashes arrive at the same moment, so to them the lightning strikes happen simultaneously. However, to someone sitting on the moving train, because it is moving towards one flash and away from the other, the flashes reach them at different times, and to them the strikes were not simultaneous.

So, which person is correct in what they witness? The answer is both of them, because simultaneity itself depends on motion, and this idea was a shock for physicists as it meant that even the ordering of events can depend on your frame of reference.

Ok, let’s move on again. Before Einstein, space was space, time was time, and small furry creatures from Alpha Centauri were small furry creatures from Alpha Centauri.

Sorry, got a bit keyboard happy there, forget the small furry creatures from Alpha Centauri

Back to space and time, before Einstein, these were always perceived as separate things, but after Einstein, physicists realised they are really aspects of a single entity. That’s right, you’ve guessed it. Spacetime

Every event in the universe has three spatial coordinates and one time coordinate, and together they form a four-dimensional reality called spacetime. You are not merely travelling through space, what you are doing is continuously moving through spacetime. Right now. At this very moment.

This brings us back to the equation that everyone knows, especially if you are a regular reader of my stuff, and are aware of the trouble I had when trying to produce a quick mid-week article on it recently.

E = mc²

Perhaps the most famous equation in history. And to translate it into plain English, without all the complicated maths this time, it basically says that mass and energy are different forms of the same thing. Matter can become energy, and energy can become matter, and the conversion factor is the speed of light squared.

Since light speed is enormous, even tiny amounts of matter contain staggering amounts of energy, and as you regulars know, this principle powers the Sun, nuclear reactors, nuclear weapons, along with many other processes throughout the universe.

While we are on the subject of the speed of light, let’s take a look at it.

Science fiction often treats the speed of light as something that can eventually be exceeded, Special Relativity, however, says otherwise. As an object accelerates its energy increases, the energy required for further acceleration rises dramatically, and near light speed the required energy approaches infinity. Because infinite energy is impossible, a material object of mass can never quite reach the speed of light. Photons can travel at light speed because they have no rest mass (remember my equations the other week?). Everything else though must remain below that cosmic speed limit.

Perhaps the most famous story in relativity is the Twin Paradox. Ready for another analogy? Good, here we go.

Imagine identical twins. One of them stays on Earth, while the other is on our imagined spaceship travelling to Alpha Centauri at near light speed before eventually returning home. When they meet again, the Earth-bound twin is older, while the space-faring twin is younger.

This sounds impossible as shouldn’t each twin see the other moving? The key to this is that the traveller accelerates, turns around and changes reference frames and the Earth twin does not. When all the mathematics is done, the traveller genuinely ages less. Which is why Matthew McConaughey has hardly aged at all when he returns from his interstellar travels and visits his aged daughter. And what is really mind boggling about this is that if fast enough journeys were possible, your future descendants could be older than you after your return!

Moving along once more, many people think relativity is only useful to astronomers, whereas in reality you and I are using it all the time as we drive around to unknown destinations, or have a nosey at our phone to see where the kids are. You’ve guessed it, I’m talking about GPS navigation

GPS satellites carry incredibly precise clocks and those clocks do not tick at exactly the same rate as clocks on Earth so engineers must correct for relativistic effects or navigation errors would rapidly build up. Every time your phone finds a location, a small victory for Einstein is taking place!

So, what did Einstein really teach us?

More than a century later, Special Relativity remains one of the most thoroughly tested ideas in science. Experiments involving high-speed particles, atomic clocks and modern technology continue to confirm its predictions. But at its deepest, the lesson isn’t a mathematical one, it’s a philosophical one.

For thousands of years humans assumed time was universal, space was fixed, and simultaneous events were absolute. Einstein showed us that none of these assumptions are true and the universe is stranger, more elegant and far more astonishing than common sense ever imagined.

Special Relativity’s big reveal is that space and time aren’t the fixed stage we assume they are as they are flexible, they stretch, they bend around each other, and they do it all in service of one stubborn rule. And that rule is the speed of light never changes, no matter who’s watching.

The Holographic Principle – Could the Universe Be Stranger Than We Ever Imagined?

Posted on August 21, 2026 by Mal Andrews

Apologies everyone, I’m a bit late this week. But, as they say, better late than never, and this week, I’m back on black holes again, with an article I promised a while back. So, settle down and start reading. It’s time get to your head round the Holographic Principle.

Imagine walking into a room and discovering that everything inside, the walls, the furniture, even you, could be completely described by information written on the room’s surface. A bit like the programming behind The Matrix.

Now then, this may sound like science fiction, but it is remarkably close to one of the most serious ideas in modern theoretical physics, and that is the holographic principle.

For centuries, we’ve assumed that if you want to describe a three-dimensional object, you need three-dimensional information. You know, a cube has volume, a planet has volume, and the universe has volume. Simple, right?

Then those pesky black holes came along and ruined everything, and physicists discovered that the amount of information a black hole can contain isn’t related to its volume. Instead, it is related to the area of its surface, the event horizon.

That would be like discovering that every book in a library could be stored not inside the library, but on its outer walls. That also meant that something very strange was going on.

Way back in the 1970s, Jacob Bekenstein and Stephen Hawking showed that black holes possess entropy, you know, a measure of information or disorder. The shocking part was that this entropy grows with the horizon’s area rather than the volume enclosed within it. And this tiny mathematical detail opened a huge conceptual door.

If the most information that can fit inside a region of space scales with surface area, perhaps the universe itself isn’t storing information the way we thought. Perhaps reality is keeping its records on the boundary.

And that is where we enter the holographic universe.

In 1993, physicist Gerard ‘t Hooft proposed a radical possibility, and then Leonard Susskind expanded it into what we now call the holographic principle.

Their idea was simply breathtaking! And that idea was everything happening inside a region of space that might be fully encoded on its boundary. Not approximately. Not metaphorically. But quite possibly exactly.

That would make the three-dimensional world we experience akin to the information living on a lower-dimensional surface.

Which leads us to a question. So… Are we living inside a hologram?

Not in the way Hollywood imagines. The holographic principle does not mean that reality is fake, and we are living in an illusory universe as video game characters.

What it actually suggests is that there may be two completely different ways to describe the same reality.

It’s time for one of those analogies I bombarded you with in last week’s article

Think of a globe and a flat map. They look completely different, right? (No flat earth comments please. We don’t do that here). One is curved and one is flat, yet they both describe the same Earth, and the holographic principle proposes something similar on a cosmic scale.

For years the holographic principle was a fascinating speculation until 1997 when Juan Maldacena proposed the AdS/CFT (the anti-de Sitter/conformal field theory (yes it will likely take another article)) correspondence, which is now regarded as one of the most important developments in theoretical physics.

The idea can be summarised as: A universe containing gravity can be mathematically equivalent to a universe without gravity living on its boundary. And if it’s true, this means that two radically different descriptions of reality tell the same story. Physicists have spent decades testing this idea, and so far, it has passed many rigorous inspections.

And then the story gets even stranger. Modern research increasingly suggests that space itself may emerge from quantum information, and one of the biggest clues comes from our old friend quantum entanglement, that mysterious connection that can exist between particles.

Some researchers now suspect that spacetime may be woven together by vast networks of entanglement. In this picture, geometry isn’t fundamental, but information is, and space emerges from it. Which gives us spacetime from information! How freakily cool is that!

Although the holographic principle is powerful, it still remains incomplete. Scientists have convincing examples where it works extraordinarily well, particularly in special theoretical universes described by AdS/CFT. But the challenge is that our actual universe does not obviously resemble those examples. And so, the full holographic description of the cosmos we inhabit remains an open problem.

So the principle stands in an unusual position as it is one of the most influential ideas in theoretical physics, it has impressive mathematical support, it may help solve the black hole information paradox, and yet nobody can confidently say whether our own universe is truly holographic.

And so, the holographic principle began as a puzzle about black holes and grew into a revolutionary possibility that everything we think exists within space may be fully described by information living on a lower-dimensional boundary.

If discoveries in the future were to confirm this idea, historians may look back on it as one of humanity’s greatest insights. It’s not that matter is fundamental, and it is not that energy is fundamental either.

But that, at the deepest level, information itself may be the fabric from which reality is built.

And I shall finish this article by saying…

Woah!!!!!

Einstein’s General Theory of Relativity – The Revolutionary Idea That Changed Our Understanding of Reality

Posted on August 14, 2026 by Mal Andrews

I’ve chosen a biggie this week folks, Einstein’s General Theory of Relativity. And boy it really is a biggie! It would take volumes and volumes of books to take you through everything, and years and years of research and study for me to write it. So, I’m going to have a go and see if I can put together some kind of short comprehensive guide for you. Ready?

Imagine you’re standing on Earth, feeling gravity pull you toward the ground. For centuries, scientists believed gravity was an invisible force acting across space. Then, in 1915, Albert Einstein popped his two penneth in and proposed something that was truly astonishing. Einstein proposed that gravity isn’t really a force at all, and that instead, massive objects such as planets, stars, and galaxies actually bend the fabric of space and time itself, and what we experience as gravity is actually the result of moving through this curved spacetime.

In a flash, Einstein had overturned centuries of thinking and by doing so he gave humanity a completely new picture of reality.

Before General Relativity, Isaac Newton’s theory of gravity was king, and his equations successfully explained falling apples, planetary orbits, ocean tides, and the motion of the Moon.

However, for everything that Newton’s laws could explain, there were still some puzzles remaining. Newton’s explanation of gravity appeared to act instantly across vast distances, while Einstein’s Special Relativity showed that nothing can travel faster than light. There were also subtle discrepancies in Mercury’s orbit that Newton’s theory couldn’t fully explain, and Einstein believed there had to be a deeper explanation, and there was.

Einstein’s breakthrough began with a simple thought experiment.

Imagine you’re trapped inside a windowless lift (elevator to my American readers).

In one scenario, the lift (elevator) is sitting on Earth, and in another, it’s floating in deep space, but it is accelerating upward. In both cases, you feel pressed against the floor. But, without looking outside, you can’t tell which situation you’re in.

This observation became known as the Equivalence Principle, and that is gravity and acceleration are locally indistinguishable, and for Einstein, this was the clue that unlocked a completely new understanding of gravity.

This is where spacetime comes in, and it is so breathtaking in its simplicity it is mind blowing.

Einstein realised that space and time are not separate things, but instead, they form a single four-dimensional structure which he called spacetime.

Now then, you have to think of spacetime as the stage on which everything in the universe exists and moves. And, to do so, I’m going give you a classic analogy.

Imagine a giant trampoline stretched tight, and as it is stretched tight, it is flat. If you now place a bowling ball in the centre of the trampoline it creates a dip, and if you now roll a tennis ball nearby, its path curves as it rolls.

The tennis ball isn’t being directly pulled by the bowling ball, all it is doing is simply following the shape of the surface, and this is how planets move through spacetime that has been curved by stars and other massive objects.

I know it’s not perfect, but this analogy captures Einstein’s revolutionary insight that it is mass that changes the geometry of the universe.

So, to your first question, I know you have loads. How does gravity really work?

And the answer to this is when most people think about gravity, they imagine an invisible force pulling objects together, however, Einstein saw something completely different.

Here’s another simple analogy (there’s going to be a few of these, so stick with me).

Imagine it’s nighttime and you are driving along a mountain road. Although you keep the steering wheel pretty straight, the road curves left, looking from above, someone might reasonably think that an invisible force has pushed your car sideways when in reality, you’re simply following the shape of the road.

According to General Relativity, planets are doing exactly this, and the Earth isn’t being pulled around the Sun by a mysterious force, it is moving along the curved road of spacetime created by the Sun. The sun is the bowling ball on the trampoline, and the tennis ball is the Earth. Geddit? Of course you do!

Ok, let’s look how that applies to the whole of the cosmos.

At the heart of General Relativity is a set of mathematical relationships called the Einstein Field Equations, and physicists often summarise them this way, and again, it is incredibly brilliant in its simplicity.

Matter and energy tell spacetime how to curve, and curved spacetime tells matter how to move, and these equations connect the contents of the universe to the shape of the universe itself! Cool, huh!

These equations can describe everything from planetary motion to black holes and even the evolution of the cosmos.

And that neatly leads us on to the next question you are bursting to ask.

“If gravity isn’t a force, then why doesn’t the Earth fly away from the Sun?”

And for that answer we have another simple analogy.

Imagine you are throwing a ball. If you throw it gently it lands on the ground nearby to you, however, if you throw it harder, it travels further and if you were to throw it harder and fast enough, the Earth’s surface curves away beneath it as quickly as it falls. The ball keeps falling but never reaches the ground, and that is essentially what an orbit is.

Earth is constantly falling through curved spacetime around the Sun.

One of General Relativity’s strangest predictions is that time does not flow at the same rate everywhere, and near a massive object, time passes more slowly, and the further away, time passes more quickly.

OK, analogy number 3? 4? I’ve lost count already.

Imagine time as a river. Far from massive objects, the river flows quickly, and near a massive object, the current slows. Two people that have been travelling through different parts of the river can reunite and discover that different amounts of time have passed for them.

This isn’t science fiction; this is science fact, as GPS satellites must account for relativistic time effects to provide accurate navigation. To really delve into time, you should read The Order of Time by Carlo Rovelli. This book is a brilliantly understandable read, and you’ll have your head wrapped around time in no time. And it’s got Smurfs in it!

Something else General Relativity told us is that light can bend. Before Einstein, all the science nerds simply assumed that gravity only affected matter. General Relativity predicted that gravity affects light as well.

And to explain it, you guessed it, another analogy.

Imagine you are riding a bicycle along a painted line on the ground, you aren’t intentionally turning. You are simply following the path beneath you. Light behaves similarly. It travels along the straightest possible path through spacetime, and if spacetime itself is curved, the path of light appears bent. Observations of the famous solar eclipse of 1919 confirmed this prediction and also made Einstein world famous.

The bending of light creates one of astronomy’s most powerful tools, and that is gravitational lensing. This is where massive objects can bend light from distant galaxies and act like giant lenses. If you hold a wine glass in front of a distant light, the image behind it appears stretched, distorted, or sometimes, even duplicated, and galaxies do the same thing to light, and astronomers use these natural lenses to study objects that would otherwise be too distant to see.

General Relativity also predicts objects so dense that spacetime becomes dramatically distorted, and, you’ve guessed it, as these are one of my favourites, it predicted black holes, and with them, their ever brilliantly baffling event horizons, which leads me to my next analogy, the river model of black holes.

Imagine a fish swimming upstream, and way ahead of it is a waterfall. While it is far away from the waterfall the little fishy can easily fight against the current, however, when it gets closer to the waterfall, the water moves faster, until eventually there is a point where the current exceeds the fish’s maximum swimming speed. Beyond that point, escape is impossible, and the little fishy is heading over. A black hole’s event horizon is similar. Beyond it, spacetime is being dragged inward so strongly that not even light can escape. But you know all this, I’ve written about it loads.

General Relativity also predicts that moving massive objects can create disturbances in spacetime itself and these are known as gravitational waves.

Drop a pebble into still water and waves spread outward in all directions. When massive objects such as black holes collide, they create ripples in spacetime that travel across the universe. And those clever scientists detected these waves directly in 2015, thus confirming another of Einstein’s remarkable predictions.

General Relativity has become the foundation of modern cosmology, and it helps explain the Big Bang, the expanding universe, the evolution of galaxies and the large-scale structure of the cosmos itself, and in many ways, modern astronomy is the story of applying Einstein’s theory to increasingly larger scales.

Unfortunately, Einstein’s theory, as brilliant as it is, isn’t perfect. Even though every major experimental test has supported General Relativity for more than a century, physicists know the theory is incomplete as it struggles to explain what happens at the centre of black holes, the earliest moments of the Big Bang, and how gravity works at quantum scales, that pesky teeny tiny stuff again, and finding a theory of quantum gravity remains one of the greatest challenges in science today.

If you remember only one thing about General Relativity, make sure it’s this

For more than 200 years, Isaac Newton’s theory of gravity successfully explained the motions of objects on Earth and the movements of the planets. In Newton’s view, gravity is a force that pulls objects toward one another. The Earth is pulled toward the Sun, the Moon is pulled toward the Earth, and an apple falls because the Earth exerts a gravitational force on it. This picture works remarkably well for most everyday situations and remains extremely useful today.

Einstein’s insight was way more radical.

According to General Relativity, gravity is not fundamentally a force at all. Instead, mass and energy change the geometry of the universe itself by curving spacetime. Planets, stars, galaxies, and even light move through this curved spacetime, following its natural paths. What we perceive as the force of gravity is actually the consequence of moving through a universe whose geometry has been distorted by matter and energy.

A useful way to picture the difference is to imagine a ball rolling across a landscape. Newton would describe the ball’s motion as being caused by forces acting upon it. Einstein would direct your attention to the shape of the landscape itself. If the ground is curved, sloped, or warped, the ball’s path changes naturally as it follows the terrain. In a similar way, planets orbit stars because they are moving through curved spacetime, not because an invisible force is reaching out and pulling them around.

This seemingly simple change in perspective transformed our understanding of the cosmos. From it emerged the prediction of black holes, the discovery of gravitational waves, the realisation that time can flow at different rates in different gravitational environments, and the modern picture of an expanding universe. More than a century after Einstein introduced his theory, it is still one of mankind’s greatest achievements, and it remains humanity’s best description of gravity and one of the most profound (I had to get that word in here somewhere) insights ever achieved in science.

And that my faithful readers, is Einstein’s Theory of General Relativity for you in a nutshell. For anyone who just wanted the 1905 Special Theory, it’s the short, sharp one about speed and simultaneity, no bendy trampolines required. You can pretend the last ten minutes didn’t happen, and, if you’re lucky, and you really want it, Special may get its own piece in a few weeks’ time.

E = mc² – The Tiny Equation That Changed the Universe

Posted on August 12, 2026 by Mal Andrews

Just a quick note before you start reading. This was supposed to be a quick hit for a midweek article, however, it actually took me bloody ages!! Surprisingly, it wasn’t just the maths that caused me issues, it was getting the damned equations into WordPress that made me swear profusely! In hindsight I should have rounded the speed of light to 300,000,000 m/s as most folk would do in an article of this nature. Me? No. I wanted to keep accuracy paramount and use the actual number which is 299,792,458 m/s. Anyway, it’s done now, so on with the article (I really hope you can make sense of it all despite the WordPress formatting).

For this week’s midweek article, just for you, my faithful few, I’m going to answer a question I’ve been sent. And that question is:

“Can you please explain E = mc²?”

And the answer to that question is:

Yes, I can. So, there we go. Question answered. Don’t forget to come back on Friday for this week’s full article on Einstein’s Theory of General Relativity.

Obviously, I’m joking. I wouldn’t leave you hanging like that. Here’s the actual answer, No, I can’t.

Sorry, still joking, I’m just trying to avoid doing the maths, you all know how much I hate doing maths, after all, I’ve only mentioned it a few times.

Ok, on to the real answer, what actually is E = mc² and what does it tell us?

Well, it may be the most famous equation ever written, yet its message is surprisingly simple, and that is, matter and energy are different forms of the same thing.

So, without further ado, let’s meet the world’s most famous equation. Ready? Of course you are!

In 1905, Albert Einstein published his Special Theory of Relativity, a paper that changed physics forever, and a few months later he published a follow up paper building on it, and in that paper was:

E = mc^2

We’ve all heard it, the majority know it’s calculation, but not everybody actually knows what it really means, and that is, this beautiful little equation tells us that every object around us contains an enormous amount of stored energy.

Your phone. Your coffee mug. A sugar cube. The classic physics paperclip. Even you. Everything with mass contains energy.

Right then, let’s break it down.

E = mc^2

E = Energy (joules). m = Mass (kilograms). c = Speed of Light

The speed of light is defined exactly as: c = 299,792,458 m/s

But, the equation doesn’t just use c, it uses c².

And that means:

c^2 = c \times c

So, if we substitute the exact value (it’s maths time) we get:

c^2 = 299{,}792{,}458 \times 299{,}792{,}458

= 89{,}875{,}517{,}873{,}681{,}764

8.9875517873681764 \times 10^{16}

That massive number is nearly 90 quadrillion, folks, that is 90,000,000,000,000,000. A seriously big number. And it is this gigantic number that is the reason even a tiny amount of matter contains an astonishingly humungous amount of energy.

To work it out, just imagine a single sugar cube sitting beside a cup of tea, and let’s assume a typical sugar cube has a mass of 4 grams

First let’s convert grams to kilograms by dividing it by 1,000: 4 grams = 0.004kg

Next were going to use Einstein’s equation: E = mc²

Now we are going to substitute the variables with the actual values:

E = (0.004)(89{,}875{,}517{,}873{,}681{,}764)

And in joules that calculation gives us:

E = 359{,}502{,}071{,}494{,}727.056

Or as a simple equation we have

E \approx 3.60 \times 10^{14}\ \text{J}

So, the answer is, one ordinary sugar cube contains 359,502,071,494,727 joules of energy in its mass.

It may not look that remarkable, but Einstein’s equation reveals that our tiny 4-gram sugar cube contains an almost unimaginable amount of hidden energy.

Which leads us straight into your next question. If a sugar cube really has that much energy stored in it, why doesn’t it explode?

And that is because, fortunately, ordinary matter doesn’t automatically convert itself into energy, and most of the energy remains locked inside the matter. Only special processes can release some of it and they are nuclear fusion inside stars, nuclear fission in reactors, and matter meeting antimatter. It is only in these situations that a tiny amount of mass is converted into energy, and you get a big bang.

A sugar cube does release energy when you eat it, and that energy is chemical energy, and it comes from rearranging atoms. Einstein’s equation is talking about something much deeper, and that is the energy contained in the mass itself. The energy your body gets from eating sugar is only a tiny fraction of the sugar cube’s total mass-energy.

Here’s a fun fact for you, if all the mass of a sugar cube could somehow be converted directly into energy, the result would be vastly greater than the energy released by burning or digesting it, and that is because chemical reactions use only a teeny tiny part of the energy hidden inside matter.

The Sun also runs on Einstein’s equation, as deep inside it, hydrogen nuclei fuse together to form helium, although the helium produced has slightly less mass than the hydrogen that went into making it, which leads to another question. Where did the missing mass go? And you’ve guessed it, Einstein’s equation gives us the answer. The missing mass became energy and this energy eventually leaves the Sun as heat and light.

That’s not all folks, there is an even bigger equation as the famous equation is actually a simplified version of a more complete relationship from Special Relativity, and that equation is:

E^2 = (mc^2)^2 + (pc)^2

E = total energy, m = rest mass, p = momentum, and c = speed of light

This equation works for everything in the universe, whether moving or stationary. Imagine our sugar cube sitting motionless on a saucer, beside a cup of tea. OK, because it isn’t moving:

p = 0

Next, we’ll substitute into the full equation:

E^2 = (mc^2)^2 + (0)^2

E^2 = (mc^2)^2

And then we’ll take the square root of both sides which gives us…

E=mc^2

And there it is, folks, the world’s most famous equation is simply a special case for an object that is not moving.

Ah, but what happen if you pick up the sugar cube and throw it across the room? Quite why you would do that, I don’t know, maybe it upset you or you have saccharophobia, an irrational fear of sugar cubes.

The sugar cube now has momentum, so:

p > 0

Then the full equation becomes:

E^2 = (mc^2)^2 + (pc)^2

Its total energy now includes energy from its mass and energy from its motion, and the faster it moves, the larger the momentum term becomes.

What about Light? I hear you say. Well, light is special because it has zero rest mass.

m = 0

And substituting into the full equation gives us:

E^2 = (pc)^2

And taking the square root gives us:

E=pc

And remarkably, the result tells us that light carries energy even though it has no rest mass. And that means that every Wi-Fi signal, radio broadcast, mobile phone signal, microwave, X-ray, and ray of sunlight carries energy because of this relationship.

Before Einstein, mass and energy were thought to be completely different things, but, after Einstein, physicists realised they are simply different forms of the same physical reality. Matter can become energy. Energy can become matter. The universe constantly converts one into the other. And all of that profound insight can be demonstrated with something as ordinary as a sugar cube. How about that!

So to summarise:

We have the famous equation:

E=mc^2

The full equation is:

E^2 = (mc^2)^2 + (pc)^2

The exact speed of light is

c = 299{,}792{,}458\ \text{m/s}

And the speed of light squared is:

c^2 = 89{,}875{,}517{,}873{,}681{,}764

Which means the mass and energy of our single sugar cube is:

m=0.004 kg

E = 359{,}502{,}071{,}494{,}727\ \text{J}

Which tells us that our ordinary cube of sugary sweetness contains an extraordinary amount of energy, and that’s because every kilogram of matter is multiplied by one of the largest important numbers in nature:

89,875,517,873,681,764

And that astonishing connection between matter, energy, stars, light, and the universe is captured in just five symbols, which is perhaps the most famous and most powerful equation that has ever been written.

E=mc^2

Entropy, Thermodynamics & Black Holes – The Article I Promised You!

Posted on August 7, 2026 by Mal Andrews

Hello again my faithful few, it is time, to discover the hidden rules that govern everything from your morning cup of tea to the edge of the universe. Are you ready? Of course you are!

Did you know, the universe has a favourite direction?

If you place a hot cup of tea on a table and it cools, if you drop an ice cube into a drink and it melts, and if you spray air freshener into a room and it spreads out, none of these events require any effort, they just happen naturally.

Yet you’ve never seen the reverse occur on its own, have you? Cold tea becoming hot, melted ice spontaneously reforming, or air freshener spray gathering back in to the can.

There’s a reason for this, which lies in one of the deepest principles of nature, and that is, you’ve guessed it, the clue is in the title, it is entropy. A subject I love so much, it gets bolded.

Entropy is the central idea of thermodynamics, the branch of physics that governs energy, heat, and work, along with the direction of physical processes.

And what’s remarkable is, entropy doesn’t just influence everyday events, it plays a crucial role in understanding stars, galaxies, time itself, and even, as I’ve touched on in a previous article or three, black holes.

And now, my faithful readers, I am going to attempt to explain the science of energy without writing a full-blown scientific paper, or a book. Are you ready? Here goes!

Now then. Thermodynamics began during the Industrial Revolution as scientists attempted to build better steam engines, and as is usual when building these types of engineering feats, what they discovered was far more important.

The same laws governing steam engines also govern chemical reactions, batteries, human metabolism, planetary atmospheres, nuclear fusion in stars, black holes, and the evolution of the universe itself.

Thermodynamics became the universal rulebook of energy.

OK. There are four laws of thermodynamics. The first is the Zeroth Law. Now, this law was established by Robert H. Fowler in the 1930s quite some time after the other three laws were established, which is why it isn’t the first law. And it’s a simple one.

If object A is in thermal equilibrium with B, and B is in equilibrium with C, then A and C are in equilibrium with each other. Simples, right? Told you it was. And as simple as this sounds this law allows temperature to be measured. Without it thermometers couldn’t exist.

Then we get the First Law.

The First Law states that energy cannot be created or destroyed, energy only changes form, chemical energy becomes motion, motion becomes electricity, electricity becomes light. However, the total amount of energy remains unchanged.

After the first law, unsurprisingly we get the Second Law

The Second Law is the famous one, you often hear about in the movies, or albums by Muse, and is where entropy enters the story.

The Second Law states that the entropy of an isolated system never decreases. While entropy may remain constant in an ideal reversible process, it naturally tends to increase, and it is this law that explains why so many processes happen in one direction only.

Next? You’ve guessed it, we have the Third Law.

And that is, as temperature approaches absolute zero, entropy approaches its minimum possible value.

So, that takes us to the first question, what is entropy?

People often hear entropy described as a measure of disorder, and as useful as that description is, it’s incomplete.

There is a deeper meaning, and that is, entropy measures the number of possible microscopic arrangements of a system. Physicists call these arrangements microstates. Which, put simply, means the more possible ways something can exist while appearing the same overall, the higher it’s entropy.

Think of it like a jigsaw puzzle of an idyllic country cottage, surrounded by blue sky with fluffy clouds, a cute picket fence and dozens of flowers growing in the garden. One arrangement produces the completed image, whereas millions of arrangements produce a random mess. Nature overwhelmingly favours the states that are statistically more likely. And that tendency is entropy.

Still with me? Good. Let’s have a look at why ice melts. Ice contains water molecules arranged in an organised crystal structure and when ice melts, those molecules gain freedom. They can occupy vastly more possible arrangements which means the liquid state therefore possesses higher entropy than the solid state. Nature generally moves toward states with more possible configurations.

Next, we have one of physics’ greatest mysteries, the arrow of time, that is, why time only moves forward.

The fundamental equations of physics often work equally well forward or backward, yet reality doesn’t. Glass shatters, eggs break, and people age etc. We never witness these events naturally reversing themselves, and it’s entropy that provides us with the explanation.

As systems evolve, they overwhelmingly move from less probable states to more probable ones, and this increase in entropy creates the direction we perceive as the flow of time.

In the nineteenth century, Ludwig Boltzmann had an incredible insight. He had connected entropy to probability with one famous equation:

\mathbf{S = k \ln \Omega}

Where: S = Entropy, k = Boltzmann’s constant, and Ω = the number of possible microstates. This equation links the visible world to the invisible world of atoms and molecules, and to many physicists (and amateurs like me), it is considered one of the most beautiful equations ever discovered.

Next, we’ll take a look at why perfect engines can’t exist

Suppose engineers build the ultimate engine, every bit of heat becomes useful work. There’s no waste, and no losses.

Thermodynamics says this is impossible. The Second Law requires that some energy inevitably becomes unavailable for useful work and is released as waste heat, so therefore, no heat engine can ever achieve 100% efficiency. Nature always demands an entropy bill.

Let’s have a look at one of my favourite examples, Black Holes, the very first article I wrote for this blog. Black holes changed everything as for much of the twentieth century, physicists believed black holes were simple objects. They appeared to have, no temperature, no entropy, and no internal complexity, and this, my friends, created an enormous problem.

Imagine throwing a book into a black hole. The book contains information and the information has entropy. If the black hole were to simply swallow everything and hide it forever, entropy would seem to disappear from the universe, and this would violate the Second Law. That means, somewhere, something was wrong.

In the early 1970s, physicist Jacob Bekenstein had a revolutionary idea and proposed, what at the time was, a shocking solution. He suggested that black holes themselves possess entropy.

At first, the idea seemed absurd. How could an object that appears completely black have entropy?

Bekenstein, however, had a realisation, and that was entropy had to be related to the surface area of the black hole’s event horizon. In effect, the horizon was storing information about everything that had fallen inside. And this was one of the most important insights in modern theoretical physics.

Soon afterward, our favourite physicist, Stephen Hawking, made an even more astonishing discovery. Using quantum mechanics, Hawking showed us that black holes are not truly black. They emit tiny amounts of thermal radiation, now known as: Hawking Radiation. Regular readers will know all about Hawking radiation, I wrote about it a couple of weeks ago, remember?

And this implied something absolutely astonishing. If black holes emit thermal radiation, they possess temperature, entropy, and thermodynamic behaviour. Black holes were no longer just gravitational objects. They were thermodynamic objects. And in some sense, they were giant cosmic heat engines.

Let’s move on to the entropy of a black hole. One of the strangest discoveries in physics is that a black hole’s entropy is proportional not to its volume, but to the area of its event horizon, and this was completely unexpected, as this meant that for ordinary objects, more volume means more storage capacity. Whereas for black holes, more surface area means more entropy. And this relationship became known as the Bekenstein-Hawking Entropy Formula, and it suggests that information about a three-dimensional region may somehow be encoded on a two-dimensional surface. This idea later inspired the famous Holographic Principle, one of the most profound concepts in modern theoretical physics, but sorry folks, once again that isn’t for now, that’ll have to be another article (which luckily for you I am working on, so it won’t be long).

What was discovered was black holes are entropy monsters. The entropy contained within a black hole is enormous. In fact, a black hole possesses vastly more entropy than an ordinary star made from the same amount of matter.

When a star collapses into a black hole, entropy increases dramatically, which means black hole formation actually satisfies the Second Law beautifully.

Far from violating entropy, black holes may represent some of the highest-entropy objects in the universe, which is why physicists sometimes describe them as the ultimate entropy engines.

And with that, it was time for another mystery to emerge from the shadows, The Information Paradox.

If Hawking Radiation causes black holes to slowly evaporate, what happens to the information that fell into them? There appears to be three possibilities to answer that question. Either information is destroyed, it escapes somehow, or, more likely, our understanding of physics is incomplete. This became known as the Black Hole Information Paradox, and it remains one of the greatest unsolved problems in physics. Entire fields of theoretical research have grown from attempts to solve it.

Today, many cosmologists believe the universe began in an extraordinarily low-entropy state and that this may govern the fate of the universe. Since then, entropy has steadily increased. Stars burn hydrogen, galaxies evolve, black holes grow, and entropy rises.

Far in the future, black holes may dominate the universe, and even they will eventually evaporate through Hawking Radiation. After unimaginable lengths of time, the cosmos may approach a state of maximum entropy known as Heat Death. This is standard cosmology, and in this state, all the stars are gone, temperature differences completely vanish, any useful work is impossible, and although energy remains, it is hopelessly spread out to be of any use to anything. The universe doesn’t run out of energy, but it does run out of opportunities to use that energy.

So, at the end of the day, thermodynamics began with steam engines, and it ended up explaining reality itself! Which again, as far as I’m concerned, absolutely boggles the mind!

To put it another way, entropy tells us why my favourite Assam tea cools, why stars shine, why time moves forwards, why engines have limits, why life can exist, and why black holes may hold the key to unifying gravity and quantum mechanics.

If the First Law says energy can never be destroyed, then the Second Law says energy becomes increasingly dispersed and increasingly difficult to use.

And nowhere is that truth more dramatic than in a black hole, where gravity, quantum physics, information, and entropy collide at the edge of the known universe.

Entropy is not merely a property of matter. It may be the accounting system for the whole of reality itself!

Five Things That Sound Completely Made Up (But Are Annoyingly Real)

Posted on July 31, 2026 by Mal Andrews

Following on from last Friday’s article, one of the side effects of learning about Hawking radiation is discovering that modern physics is less a collection of facts and more a collection of increasingly unsettling revelations. Every time you think you’ve found the weirdest thing in the universe, physics quietly says, “Hold my equations.”

Here are five examples.

1. Right now, you are hotter than a black hole.

Let’s begin with an insult to black holes. And that is that right now you are hotter than most, if not maybe all, the black holes in the universe

Despite their reputation as the ultimate cosmic monsters, most black holes are astonishingly cold. Hawking showed us that black holes possess a temperature, and the larger the black hole, the colder it becomes. Therefore, a black hole with roughly the mass of our Sun would have a Hawking temperature of only a tiny fraction of a degree above absolute zero.

Meanwhile, you are sitting there at around 310 Kelvin (37°C), radiating infrared energy into your surroundings like a particularly self-satisfied space heater. So, thermally speaking, you’re absolutely thrashing a stellar-mass black hole. That is the same object capable of swallowing stars is, from a temperature perspective, a pathetic overachiever. The universe’s most feared gravitational predator is colder than deep space and vastly colder than the cup of tea that is slowly cooling beside me.

Hawking radiation revealed that black holes aren’t just gravitational objects. They’re thermodynamic objects. And thermodynamics has a wonderful habit of humiliating our intuitions.

2. Space ain’t empty.

The phrase “empty space” is one of the most misleading expressions in science. You got it, empty space is most definitely not empty.

What looks like nothing is actually a restless sea of quantum fields. According to quantum field theory, even a perfect vacuum contains fluctuations, tiny disturbances that constantly appear and disappear throughout space. This isn’t a rare occurrence, it’s happening everywhere, right now, around you, and, amazingly, it’s happening inside you! Between every atom in your body! Creepy and weird or what!!

In fact, Hawking radiation exists because black holes interact with these quantum fluctuations near their event horizons, and without the vacuum’s constant activity, Hawking’s discovery wouldn’t work. Which brings us back to that unsettling conclusion that nature doesn’t seem particularly fond of “nothing.”

Give the universe an empty stage, it’s competing with the best improv stand-up comedians. It immediately starts improvising itself!

3. Black holes ain’t that heavy.

If black holes are gravity taken to the extreme, neutron stars are gravity’s terrifying warm-up act. A teaspoon of neutron star material would weigh around a billion tonnes

Now then. A neutron star forms when a massive star dies and its core collapses so completely that atoms themselves are crushed. Electrons and protons merge into neutrons and produce an object roughly the size of a city but containing more mass than our Sun.

The result of this is density on a scale that defies common sense. A single teaspoon of neutron star material would weigh roughly a billion tonnes. That’s not a billion kilograms. That’s a billion tonnes. The sort of weight that makes the phrase “pick it up carefully” somewhat academic.

If you somehow brought that teaspoon to Earth, it wouldn’t politely sit on a kitchen counter and reality would very quickly become an SEP (you know what that is, you’ve read the Hitchhikers Guide to the Galaxy, it’s when Ford and Arthur arrive at lords on a battered sofa at the beginning of Life, the Universe, and Everything, Ford, clocking Slartibartfast’s ship out of the corner of his eye has to explain to Arthur there’s an SEP over there, try and catch it unawares by glimpsing it from the corner of your eye). Somebody else’s problem.

And at this point, every Futurama fan is now thinking exactly the same thing. “Wait… isn’t this basically Nibbler?” To which science’s answer is both inconvenient and hilarious, and the answer is, “yeah, sort of.”

Nibbler’s species, the Nibblonians, are famously absurdly dense. In one episode, Nibbler casually produces poo that weighs thousands of pounds, despite Nibbler himself being roughly the size of an enthusiastic housecat. For once, science fiction wasn’t completely making things up. A neutron star packs so much mass into such a tiny volume that a teaspoonful would weigh about a billion tonnes. Compared to that, Nibbler is practically watching his figure.

Somewhere in the universe, one suspects Nibbler is looking at a neutron star, nodding approvingly, and muttering, “Hmm… at last… a sensible-sized snack.”

Physics occasionally likes to remind us that density can be every bit as terrifying as size. And occasionally, it reminds us that Futurama was alarmingly well-informed.

4. Whatever is out there in the blackness, we can’t see it.

If Hawking radiation teaches humility, dark matter delivers the knockout punch. And that is most of the universe appears to be made up of something we can’t actually see.

For centuries we assumed that stars, planets, gas clouds and galaxies were the universe. Then astronomers started measuring how galaxies rotate, and the numbers didn’t add up.

Galaxies should have flown apart. But, instead, something invisible appeared to be providing extra gravity and holding everything together. Astronomers now call this missing ingredient dark matter.

And here’s one of those questions, you, my lovely readers, like to ask. What is dark matter?

The awkward answer is we still have absolutely no idea what it is. What we can infer is its existence from its gravitational effects. That is, we see the way it influences galaxies and bends light, but direct detection remains elusive. The evidence, however, says something is there. We just don’t know what.

Imagine discovering that most of your house consists of invisible rooms nobody can enter. That’s roughly where modern cosmology currently stands with dark matter.

5. What the hell is light doing?

And finally, quantum mechanics saves its strangest trick for last, and that is reality refuses to make up its mind until you look.

This is one of my favourites, and you can easily amaze your family and friends with it. This is the famous double-slit experiment, and it works like this.

If you fire particles through two narrow openings and don’t measure which slit they pass through, the resulting pattern suggests each particle behaves as if it travelled through both slits simultaneously.

Measure which slit it used and the pattern changes completely and the wave-like behaviour disappears and suddenly the particle acts as though it picked a side all along.

This doesn’t mean consciousness magically creates reality, despite what countless internet memes may suggest. What it does mean is observation and measurement play an extraordinarily deep role in quantum mechanics.

The universe, at its most fundamental level, appears less interested in giving definite answers than we would like, and it behaves more like a collection of probabilities than a collection of certainties.

Which is either fascinating or deeply irritating, depending on how much sleep you’ve had.

As I said, you can amaze your friends with this one, and I first saw this demonstrated in a physics class in high school many, many moons ago. All you need is a laser pointer and a couple of perfectly parallel holes in a piece of cardboard. Copy and paste this into google and it will show you how:

Can you do your own double slit experiment with cardboard and a laser pointer?

Let’s link these all together.

At first glance, these facts seem unrelated. One is about black holes. One is about empty space. One is about neutron stars. One is about dark matter. One is about quantum mechanics.

But they all point toward the same uncomfortable conclusion. Reality is under no obligation whatsoever to resemble common sense.

Black holes glow. Nothingness isn’t empty. Matter can become unimaginably dense. Most of the universe appears invisible. And particles sometimes behave as if they’ve forgotten how choosing works.

Hawking radiation sits right in the middle of this collection of cosmic absurdities. It exists because gravity, quantum mechanics, thermodynamics, and information theory all collide at the edge of a black hole.

And every time physicists dig deeper into that collision, the universe responds with another fact that sounds fake, isn’t fake, and somehow makes everything even stranger.

I tell ya. You simply cannot win with Physics. Sort one thing out and it throws a spanner in the works.

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