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.

Some of you asked: “How Do You Know So Much?” And honestly? Obsession, mostly. And I won’t shut up.

Posted on July 28, 2026 by Mal Andrews

Hi folks, quick interim post.

A few of you have been asking how I know so much about this stuff and how I write my articles. So, I thought I’d give you a little insight.

Truth is, I don’t know everything, obviously no one does, and although I’m not a professional physicist, I am a very well-read and well-studied amateur.

I got into it via my father, whose interest started with radio propagation when he was in the RAF. He was always fascinated with physics and space travel, planetary science, and in particular, anything to do with the possibilities of FTL communications.

In 1996 I bought my first tiny house in a small market town a few miles south of Norwich, and my dad lived around the corner. At the time I was working shifts in a factory, a week of days a week of nights, then I would get a week off.

During this time and for most of the rest of the nineties, my dad was always over and making use of my computer knowledge and internet and he introduced me to sites, such as Warp Drive When, and Breakthrough Propulsion Physics and other fun stuff. And it wasn’t long before I was hooked, and within a couple of years my knowledge had far surpassed my father’s.

I’m a serial learner, once I get my teeth into a subject I don’t stop. It’s an obsessive trait I’ve had all my life, and only in recent years have I discovered it’s due to OCD/ADHD/Autism. Every one of us is on the spectrum somewhere, for me and my particular place on it, it has turned me into a compulsive seeker of knowledge.

As for the articles themselves, I bang out a rough draft of what I know on the subject matter I have chosen, and then I do my research. I know quite a lot of useless stuff, how it works, when it was first performed etc. Once my draft is complete, I then start the research to make sure I’ve got the science correct, haven’t missed anything, and check timelines and people etc. I have a ton of books on the subjects I write about, and I have also subscribed to several scientific journals over the years and have those, Nature, Science, JBIS and a few others. And of course, I have the internet.

With the Quantum Teleportation article, I remember the experiments and I remember the time, and as I said in my article, I was genuinely so excited at the time I wouldn’t shut up about it. As I said above, once the draft is written, I then google it to make sure I’ve got all the awesome dudes who participated, as readers can be ruthless if I make a mistake, miss someone out, or get something wrong.

I then do a second phase over the whole thing and rewrite it before I re-read it out loud to myself, as this is the best way to pick up errors in the narration, typos, dodgy grammar etc.

Once I’m satisfied with it, I send the final draft to some very old friends from school, get them to read it and to see if it makes sense to them. With their feedback, I tweak the final article and it’s ready to go. This is also why some typos and wrong words still get through occasionally.

And that’s it. Physics is a subject that I love, and I love it so much, I want to share it with everybody else, so they will love it too.

When I resurrected this WordPress site after a four-year hiatus, I wanted to write about general sciency stuff. A bit of physics here, a bit of astronomy there, and a bit of paleoanthropology (my first love, don’t get me started on it, honestly, I won’t shut up for days!) in between.

As physics has consumed most of my adult life though, that is the direction my writings have naturally taken, and going forward, apart from the odd article in the other sections from time to time, physics is where it looks like it’s staying.

One last thing before you go. I love receiving your messages, and I have to admit I was a bit overwhelmed at how engaged some of you guys are, flattered at how many new readers are joining, and I’m genuinely thrilled at the messages I have received. Mostly via social media, which is why I added the email address to the home page.

If you want to get in touch to suggest future articles, point out mistakes, or even have a go (I’ve had a couple of those), please do. At present I am able to reply to everyone who gets in touch, unless they’re a complete arsehole.

Thank you for your time. You are AWESOME!

Mal
hello@malandally.co.uk

The Black Hole Glow: A Journey into Hawking Radiation

Posted on July 23, 2026 by Mal Andrews

Howdy my loyal readers. I’d like to start my saying thank you for the messages I’ve received asking if there is anything else they should know about black holes, and as they are a common theme through most of my articles, I’m going to indulge you with this one, on how Stephen Hawking discovered that the darkest objects in the universe may slowly evaporate away

By any reasonable definition, black holes should be simple. They pull things in. Nothing gets out. End of story. Yet in 1974, Stephen Hawking discovered something astonishing, and that was, black holes are not completely black. Given enough time, they glow, lose mass, shrink, and may eventually disappear altogether. That prediction is now known as Hawking radiation and remains one of the most profound (you’ve heard my ear worm already) insights in the history of physics.

This was a problem nobody expected, although I’m pretty sure Stephen Hawking had an inkling. You see, Black holes emerge naturally from Einstein’s theory of General Relativity. According to the classical picture, they are regions of space where gravity becomes so powerful that nothing, not even light, can escape once it crosses the event horizon. I know, I know, this is old news to you guys, I’ve stated it several times in previous articles.

For decades, physicists assumed black holes could only grow. Matter falls in. Energy falls in. Nothing comes out. Yeah? Then along came Stephen Hawking, and he combined Einstein’s gravity with quantum mechanics and arrived at an answer nobody could have anticipated. Black holes should emit a faint thermal glow. And this implication was extraordinary. Simply put, it meant that Black Holes could die.

As humoungously massive as it is, the Universe is never truly empty, and to understand Hawking radiation, we need to start with a strange feature of quantum mechanics, and that is what appears to be empty space isn’t actually empty.

According to quantum field theory, the vacuum of space is filled with fluctuating quantum fields. That is, teeny tiny disturbances constantly occur throughout space, causing particle-like excitations to briefly appear and disappear. Something that physicists call vacuum fluctuations.

OK. This bizarre activity actually happens everywhere in the universe, and this includes some of the most extreme environments surrounding a black hole.

And this takes us to the famous story that everyone learns. And that is, the most common explanation of Hawking radiation goes something like this:

Near the event horizon, a particle and antiparticle appear as a pair. Now then, normally they would immediately annihilate each other, but if the pair forms close enough to the event horizon, gravity can separate them before they reunite. Which means, one particle escapes into space, while the other one falls back into the black hole. To a distant observer, the escaping particle looks like radiation emitted by the black hole itself.

And this is because, the particle that falls inward, effectively carries negative energy relative to faraway observers, thus reducing the black hole’s mass, so over immense stretches of time the black hole slowly evaporates.

It is an absolutely, beautiful explanation.

But, and there’s always a but, you know this by know, surely guys, there’s one problem.

This isn’t really how Hawking derived the result.

To look at the deeper truth, among physicists, this particle-pair story is considered a useful mental picture, but is not the actual mathematics (maths again, I know. Regular readers already know my issue with maths). Anyway, Hawking’s original calculation used quantum field theory in curved spacetime. And that is, the essential idea is subtle. Different observers can disagree about what counts as empty space. A vacuum for one observer may appear to contain particles to another observer. But, near a black hole’s event horizon, spacetime is distorted so severely that these differing perspectives become physically important

When Hawking compared the state of quantum fields before and after a black hole forms, he discovered that an observer far away would detect radiation emerging from the black hole. So, in other words, Hawking radiation is less about particles popping out of nowhere, and more about the deep relationship between quantum fields, spacetime, and observation itself.

One of Hawking’s greatest discoveries was that black holes possess temperature, and the temperature of a black hole is inversely proportional to its mass, so the heavier the black hole, the colder it becomes, and this leads to a surprising consequence.

A supermassive black hole containing millions or billions of solar masses is incredibly cold, and a tiny black hole is extraordinarily hot, and this relationship means, small black holes radiate far more efficiently than large ones.

Because Hawking radiation carries energy away, the black hole loses mass, and this results in the slow death of a black hole.

As it shrinks, something curious happens. The black hole gets smaller as its temperature rises, then radiation increases which causes the mass to decrease even faster, and therefore the process accelerates.

If the theory is correct, then the final phase could end up with an enormous burst of energy, however, what exactly happens during those final moments remains unknown.

If you got the time to watch one, don’t expect to watch one evaporate as the evaporation process is incredibly slow. A black hole with roughly the mass of our Sun would survive for approximately 10⁶⁷ years, and this is one hell of a lot of zeros, and an incredibly long time. Trillions upon trillions upon trillions of times longer than the current age of the universe. Told you it was a long time.

And what’s more, supermassive black holes live even longer! Fortunately for the universe, black hole death is not an urgent problem, and nothing to worry about. Not for a verrrrrry longtime, at least!

Before Hawking’s discovery, physicist Jacob Bekenstein, argued that black holes should possess entropy, a measure of information content (remember my last article? You did read it, didn’t you?), and Hawking’s calculations confirmed this. In fact, black holes possess staggering amounts of entropy. Even more surprisingly, that entropy scales with the surface area of the event horizon rather than the black hole’s volume!

This observation helped inspire one of the deepest concepts in modern theoretical physics, and that is the Holographic Principle (you know this, I mentioned it way back in my original Black Hole article). This principle suggests that information contained within a region of space may be fully encoded on its boundary surface. It may sound like science fiction, but it has become one of the central ideas in attempts to understand quantum gravity

There’s a problem though, and that is the Information Paradox, and that is the question that changed theoretical physics forever.

Let us suppose a black hole swallows, my laptop I’m writing this article on, books, planets, stars, people, and entire civilizations and the specific details seem to vanish behind the event horizon.

If the black hole later evaporates and only thermal Hawking radiation remains, where did the information go? And that, is what has become known as the Black Hole Information Paradox.

The paradox appears to pit two fundamental pillars of physics against one another. Again, you know this, I’ve mentioned it before. It pits General Relativity against Quantum Mechanics. And this is because quantum theory normally forbids information destruction. What’s surprising is, Hawking’s original result seemed to imply exactly that. And that is why many physicists consider this one of the deepest unresolved problems in science.

Modern research increasingly views Hawking radiation as an entanglement phenomenon. The radiation escaping from a black hole appears linked to degrees of freedom hidden behind the event horizon, and these quantum correlations may play a crucial role in preserving information.

This current line of thinking has driven decades of research involving Quantum information theory, string theory, holography (my old, now dead, dad was a big fan of holography), and quantum gravity, as well as many other areas.

Moving on, there is another remarkable discovery that Hawking radiation appears closely related to the Unruh Effect.

The what, I hear you say? Another topic for later? Sorry, yes (picture me doing an emoji grimace in apology as I type this), the Unruh Effect predicts that an accelerating observer can perceive empty space as containing thermal radiation. And that is what one observer sees as a vacuum, another observer sees as heat. Many physicists suspect both effects arise from the same underlying physics linking horizons, acceleration, and quantum fields.

Which brings us to the puzzles of tine scales. And that is, there is another challenge lurking inside Hawking’s theory.

When researchers trace Hawking radiation backward in time, some calculations appear to involve wavelengths smaller than the Planck scale (you know what that is), where known physics may stop working completely, and this issue is called the Trans-Planckian Problem. Which suggests we may need a deeper theory of nature to fully understand what is happening near the event horizon of a black hole.

Ah, who was that at the back, another question do I hear? Have we ever seen Hawking Radiation?

Surprisingly, the answer is…

No. We haven’t.

Despite being one of the most famous predictions in science, Hawking radiation has never been directly observed from a real astronomical black hole, and that is because the effect is simply too faint. Remember how long it would take to observe it? That is how faint it is. Even paint dries at the speed of light in comparison. (It doesn’t, bit that sounded cool, didn’t it!).

However, researchers have built laboratory systems that mimic the behaviour of event horizons using optical fibre, fluid systems, and Bose-Einstein condensates, and these analogue systems have produced Hawking-like radiation and, yes there’s another and, in recent experiments, even evidence of the associated back-reaction effects predicted by theory! Cool huh?

While these are not actual black holes, they do provide valuable support for the underlying physics, which leaves us with the final mystery.

And that is perhaps that the most important thing about Hawking radiation is not the radiation itself. There is a deeper lesson, that black holes sit at the intersection of humanity’s three greatest theories, General Relativity. Quantum Field Theory, and Thermodynamics. Unfortunately, those theories do not fit together perfectly, but Hawking radiation exposes the cracks.

Hawking radiation tells us that spacetime has temperature, that gravity may be linked to information, and that entropy and geometry are somehow connected. Oh, and that our deepest theories are still incomplete.

More than fifty years after Hawking’s discovery, physicists are still trying to understand what the phenomenon is really telling us.

The black hole’s faint glow may ultimately reveal not just how black holes die, but how reality itself is built! I’ve said this before at the end of my articles, and I’m going to say it again. How amazingly awesome is that!!

Quantum Teleportation: Not Star Trek, But Still Pretty Wild

Posted on July 17, 2026 by Mal Andrews

Hello my lovely readers, you may be few, but I love you all the same.

Having had a read through my previous articles since I started this whole bringing physics to the masses journey, I noticed there’s a nice progression developing: Gravity > Relativity > Entanglement > Bell’s Proof, a quick side step into the footy (let’s not talk about that), which leads naturally onto this week’s article:

Quantum teleportation.

Now then, there’s a misconception about teleportation, and I’ve touched on it with my Star Trek allegories in previous articles.

When most of us hear the word teleportation, we probably all think of Captain James T. Kirk demanding that Scotty gets the malfunctioning transporter fixed pronto and beams him up (or Benjamin Sisko making the same demand of Chief O’Brien, or Captain Janeway…. Sorry, got a bit carried away, on with the article). Quantum teleportation is both less dramatic and far more profound (every time I type the word profound, I can hear Prof Brian Cox saying it in my head).

Unfortunately, scientists have not discovered a way to transport humans, objects, genesis devices, or even particles from one place to another. What they have discovered is a way to transport the quantum state of a particle, that is a complete description of its quantum properties, from one particle to another, potentially over vast distances.

In other words, quantum teleportation does not move matter, it moves information.

And that distinction may reveal something fundamental about the nature of reality.

So, if it’s not Star Trek personnel being teleported, what is?

To understand quantum teleportation, we first need to understand a quantum state.

Again, as I mentioned previously, unlike a classical bit, which can be either 0 or 1, a quantum bit, or qubit to give it its correct term, can exist in a superposition of all states simultaneously: it can be zero, one, or both, at the same time. The state of a qubit contains all the information that can be known about it.

The remarkable achievement of quantum teleportation is that the exact state of one qubit can be recreated in another distant qubit without ever measuring and copying the original state. The original state disappears, and the new state appears elsewhere. There is nothing physical travelling between the two except for a teeny tiny amount of ordinary information.

Quantum teleportation relies on three extraordinary ingredients.

The first ingredient is quantum entanglement.

When two particles become entangled, they cease behaving as independent objects. Instead, they become part of a larger quantum system whose properties are linked regardless of the distance separating them. You know what’s coming, don’t you? Yep, you’ve got it, this is what our old mate Albert Einstein famously referred to as “Spooky action at a distance.”

You’ve read my previous article on Bell’s Inequalities, so you know this already, but I’m going to repeat myself again anyway.

Today, entanglement is one of the most experimentally verified phenomena in physics.

On to ingredient number two. The sender (traditionally called Alice, but who I have renamed Betty in honour of my dear old late Mum), performs what’s known as a Bell-state measurement on the particle she wants to teleport and her half of an entangled pair. This measurement destroys the original quantum state, this destruction is not a bug though, it’s a requirement.

Ingredient three is the classical communication.

Betty then sends Bob, the receiver, two ordinary classical bits describing the measurement result.

It is only after Bob receives those bits that he can perform the operation needed to reconstruct the original state on his entangled particle.

At that moment, the teleportation is complete.

Sound familiar? If you read my “Spooky Action at a Distance” series, it should. I’m about to reuse that same trick about entanglement and the speed limit on information. If you haven’t read it yet… well, what are you waiting for?

Now we have one of the biggest misconceptions concerning quantum teleportation. Why doesn’t it break the speed of light?

Because entanglement creates correlations that appear instantaneous, but usable information still cannot travel faster than light. Bob cannot reconstruct the teleported state until Betty’s classical message arrives. This keeps Einstein’s theory of relativity perfectly safe and intact. No matter how strange quantum teleportation appears, and I know I’m repeating myself here, it does not allow faster-than-light communication.

Let’s look at the rule that makes this all possible, which is a fundamental principle of quantum mechanics called the No-Cloning Theorem. This rule states that an unknown quantum state cannot be copied perfectly, essentially meaning teleportation doesn’t produce two versions of the same particle state, the original state is destroyed, and the distant state is created. Quantum teleportation is a transfer, not a duplication.

The theory of quantum teleportation was first proposed in 1993 by Charles Bennett, Gilles Brassard, Claude Crépeau, Richard Jozsa, Asher Peres, and William Wootters. Their groundbreaking paper showed how an unknown quantum state could be transferred using a combination of entanglement and classical communication. If you really want to have a deep dive into it, let me know and I’ll send you the paper. It took only four years for researchers to successfully demonstrate the effect experimentally using photons in 1997. I remember being really, REALLY, excited at the time, I still get goosebumps looking back to when I first heard the news.

What had once sounded like science fiction had become a laboratory reality.

To me, and I’m sure to many others, this has become one of the greatest ironies of modern physics. Poor Einstein, the phenomenon he disliked most of all, quantum entanglement, became the foundation of quantum teleportation. However, the universe turned out to be even stranger than Einstein imagined.

That’s where Bell came in with his theorem I tried to explain (and hopefully succeeded) in my previous article before the footy one.

For decades, some scientists hoped that hidden variables might explain away Einstein’s quantum weirdness. John Bell showed that certain predictions of quantum mechanics could be experimentally tested and the results repeatedly favoured quantum mechanics and ruled out large classes of local hidden-variable theories.

If it wasn’t for Bell, quantum teleportation might still be considered an interesting mathematical idea rather than a physical reality.

Ah, another question from you? How far have we been able to teleport?

Well, it’s actually a great deal further than you probably think. Quantum states have been teleported using photons, atoms, electrons, superconducting circuits, and solid-state quantum systems.

Researchers have demonstrated space-based teleportation using China’s Micius satellite over distances exceeding 1,000 kilometres. And more recent experiments have teleported quantum information between different physical systems and over telecom-compatible networks designed to support future quantum communications. Just this year, researchers reported teleporting a photon’s state between physically separate quantum dots connected across a 270-metre free-space link, another step toward practical quantum networking.

Looking to the future of this amazing technology, scientists believe quantum teleportation will one day become one of the foundational technologies of a future quantum internet.

Instead of simply sending data, future quantum networks may distribute entanglement between thousands or millions of devices. Quantum teleportation could be used to transfer qubits between quantum computers. It could also be used to construct ultra-secure communication links, enable distributed quantum computing, and build true global-scale quantum networks.

Can you imagine quantum processors in London, New York, and Tokyo acting like pieces of a single giant computer? Well folks, that’s the long-term vision.

Ok, ok, I know you’re desperate to ask the question everyone asks. Could we teleport a person?

Well, in principle, quantum mechanics doesn’t obviously forbid it, but in practice, it is almost unimaginably difficult.

A human body contains roughly 10²⁸ atoms, each participating in an immensely complex web of quantum interactions. Capturing every detail required to reconstruct a person would involve a truly humongously astronomical quantity of information. Oh, there’s also another problem.

Don’t forget the no-cloning theorem in the rules above. The original transported person would have to be destroyed during the process, which raises a somewhat disturbing philosophical question. If a perfect copy appears elsewhere while the original is destroyed, did the person actually travel? Or were they killed while an identical replacement appeared at the other end.

That is a question that science currently has no answer for.

And here we can link back to black holes and wormholes. Deep developments in modern theoretical physics suggest that quantum teleportation may connect to mysteries far beyond communication technology.

Researchers studying black holes discovered unexpected relationships between entanglement, information, spacetime, and wormholes.

There’s the famous proposal, known as ER = EPR, yep, that one from another of my previous articles, which suggests that entanglement and wormholes may be two descriptions of the same underlying phenomenon. Although this is still speculative, these ideas hint that teleportation may reveal something truly profound (there goes Prof B. Cox again. I didn’t know it was possible to have one person saying a single word as an earworm) about the structure of the universe itself.

And then we get to the biggest mystery of them all. Perhaps the most extraordinary aspect of quantum teleportation is that nobody fully understands why reality allows it.

The mathematics works flawlessly and the experiments work repeatedly. And the technology is rapidly advancing.

Yet the deeper philosophical question remains.

Why should information be able to move through the universe in this way?

Quantum teleportation sits at the crossroads of quantum mechanics, information theory, computing, cosmology, and philosophy. Beginning as a clever theoretical idea in 1993, today it is helping scientists build the foundations of the quantum internet.

Who knows, tomorrow, it may help explain nothing less than the nature of space, time, and reality itself! Wouldn’t that truly be profound!

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