10 Things About the World Physicists Can’t Explain

Science is a helpful tool to explain the world around us. Observation, experimentation and some intuition go into determining how things work and why. One of the best things about science is that it’s malleable. Science isn’t trying to be a religion, it’s just trying to explain things. If we learn something new, science changes to accommodate that. Because of the way science works, there are always going to be things it can’t account for simply because we don’t have enough information yet. 

10. Why Does Time Go Forward?


Most of us take time for granted. It’s something that flows and we’re just along for the ride, right? Well, tell that to a physicist for whom the idea of flowing time is likely ridiculous. Anything that flows or goes forward, anything that moves, does so at a speed. What’s the speed of time? The question is basically an oxymoron. How could time move at a speed when speed is change that occurs over time? It’s like using a word to define itself, it can’t be done.

All of that said, few people would deny that time does move forward. We don’t go back and relive moments. Things don’t happen in reverse. So time does move forward. But how? And why? Why doesn’t it go backwards? There don’t seem to be any laws in physics that govern the flow of time, which makes it a complicated issue.

Ludwig Boltzmann suggested the answer to the arrow of time was entropy. The universe tends to flow towards increased entropy, and this happens when time moves forward as we perceive it. The theory is basically that everything in the universe falls apart more easily than it holds together, and that’s high entropy. For things to stay together, entropy would have to decrease, and that would be stepping back. The universe, and time, don’t work like that. 

For a moment, it all makes sense. But then you have to remember the laws of physics aren’t affected by the flow of time. So the theory that entropy increases as you go forward would only make sense if it increased as you went backward in time, which ruins Boltzmann’s whole theory. And the end result is that time does seem to be going forward all the time. Many other thinkers have tried to pick up where Boltzmann left off and all of them ended up in the same place. Time keeps going. We just don’t know why. 

9. Magnetoreception

You may have heard that birds are able to migrate by following the magnetic field of the earth. That’s how they seem to always show up in the same place every year, and navigate hundreds or even thousands of miles. It’s a very cool theory to explain what, to humans, is remarkable behavior. But we’re still not sure how that works. And even weirder, we might be able to do it as well.

The nature of a bird’s ability to follow magnetic paths has been debated for some time. At first scientists posited that iron in their beaks helped them navigate magnetic paths. Then came the idea that a protein in their eyes lets them see magnetic fields.There is evidence to suggest this may be the case, but it’s not definitive. The receptor that might allow animals to navigate this way has never been identified, so the entire mechanism is still mysterious. 

8. Glass


Have you ever heard that glass is not a solid but an extremely slow-moving liquid? Well, it’s not. But what it is remains somewhat of a mystery to science. The transition from its liquid state to a solid state leaves questions unanswered. The glass phase is actually a term used to describe matter that should be in a solid state but still exhibits some characteristics of a liquid state.

Scientists have proposed classifying glass as a new state of matter beyond solid or liquid that can account for its unique characteristics. It would essentially mean the terms of physics are altered to account for glass, because it technically doesn’t fully meet the requirements of either state as it is. 

7. Matter-Antimatter Asymmetry

In lab conditions you can create antimatter, a particle of matter that is the opposite of matter. Antiprotons are the antimatter version of protons, a positron is the antimatter version of an electron. Basically the same particle, but with an opposite charge. If antimatter meets matter, the two cancel each other out. But of greater importance in the grand scheme of the universe is the fact that when you make antimatter, you make matter as well.

If the Big Bang created all the matter in the universe, then the generally accepted belief is that it created an equal amount of antimatter. But so far science has observed an awful lot of matter and very little antimatter out there. So where did it all go? That’s the matter-antimatter asymmetry problem.

It’s possible that during the formation of the universe, as particles were decaying into matter or antimatter that something intervened in matter’s favor. Something caused far more particles to form as matter than antimatter which is why there is such a disparity today. But if that did happen, then the reason is completely unknown to science. 

6. Dark Matter

dark matter

Dark matter is one of the great mysteries of the universe and also one of the few with a very cool name. It sounds enticing, right? Dark matter. But what the heck is it? Science has long supposed the universe must be full of dark matter to account for its mass. The way gravity behaves in the universe suggests there is an abundance of matter we can’t see. This is what we’ve called dark matter. There is so much of it that it holds entire galaxies together. That’s the idea, anyway.

Unfortunately, not being able to see something makes it very hard to explain. It’s been theorized that maybe there is no such thing as dark matter at all. 

5. Why Ice is Slippery


This entry comes with a caveat. It’s not that science doesn’t know why ice is slippery, it’s that the issue is more complicated than simply saying “because it is.” And there is some debate over exactly why ice is slippery because it might not always be the exact same reason. 

The slipperiness of ice depends on friction. Something is slippery as a result of friction, or the lack thereof. It’s not a quality of ice in and of itself. But under the right conditions, ice may offer very little friction between itself and your feet, for example. That’s why you fall down. So the physics questions deal with what causes that friction?

Ice will usually have a very thin layer of water molecules on its surface. The weirdness of how this affects friction comes from determining just what state that water is in. If it’s just a single atom thick, it can technically be considered part of something called a 2D gas regime. If there are more molecules, it may be part of a liquid regime. The difference is that the gas is more mobile, and the liquid has viscosity. Both affect friction and can make ice slippery, but in different ways. 

As a gas, the molecules roll around underfoot. As a liquid, they actually lift your foot off the ice very slightly. These factors have left it a debatable issue as to what exactly it is that is making ice slippery and, frustratingly, they can change. So one may be right for a certain patch of ice, and not for another. So there is no constant, easy to identify reason for why exactly ice is slippery. But rest assured that it usually is. 

4. Why is Gravity So Weak?


Compared to electromagnetism and nuclear force, gravity is remarkably weak. It’s one of the four fundamental forces but it appears to be literally trillions of times weaker than the others. That’s a bit of a pickle for science because it doesn’t make a lot of sense. 

One theory that has been put out deals with dimensions, which we’ll cover later. The idea is that there may be some extra quantum dimensions we aren’t really aware of. If gravity is able to work in those dimensions, maybe we’re just losing a lot of the power it should have over there. 

The problem with this particular theory is that it remains just that right now, a theory. It may be proven one day in the future as experiments seek to explore the attraction between objects, but for now we just don’t know. 

3. Metal Whiskers


There’s a mysterious problem happening in machines all around the world that most of us never notice. Metal has a habit of forming whiskers; tiny little metallic filaments that can be hundreds of times thinner than a human hair and seem to grow out of the metal itself. They’ve haunted electronics for decades and so far no one actually knows where they come from.

These tiny metal whiskers have a habit of building up and causing electronics to malfunction. They were first observed in the second world war when they were determined to be the root cause of radio malfunctions. To offer some perspective, it’s estimated that the damage to this day from whiskers is in the billions of dollars. 

The whiskers form on many kinds of metal, and when they get long enough, they can connect metal components and cause short circuits. 

It’s been theorized that metal stress or electric fields have led to the formation of whiskers, but there’s still no definitive answer.  

2. How Many Dimensions Are There?

The concept of dimensions gets more and more complex the higher you get. Three dimensions are easy for most people to grasp because they readily explain the world around us. These are spatial dimensions and cover height, width and depth. That makes sense because everything we see around us falls into those dimensions.

Slightly more complex but still pretty easy to grasp is the fourth dimension, which is time. A sandwich had height, width, and depth but it’s also moving forward in time with the rest of us. So we can’t observe the fourth dimension with the same easy we see the first three, but it’s still more or less easy to understand. The fifth dimension is where people start hurting their brains. 

In order to explain the universe, scientists developed String Theory, which seeks to make quantum mechanics and general relativity work together. And it can do this if we have extra dimensions. In fact, for string theory to work, we need 11 dimensions, or 10 plus time. In this theory, those extra dimensions are down with Ant-Man in the quantum realm, so small that we can’t observe them with the ease we can observe the first three dimensions. 

Bosonic string theory goes a step beyond and says there are 26 dimensions. The reason we can’t observe all these dimensions is because they hide in plain sight in ways that exist beyond our ability to observe. One popular example is a power line. Look at it from the ground and it’s just a flat line from point A to point B. Get close and you’ll see it’s round and has dimension to it. We’re all just looking at the universe from the ground, only able to observe a small part of how it works. 

1. How Big is the Universe?


When physicists talk about the size of the universe, they are invariably discussing the observable universe, and it is vast. It has a diameter of about 92 billion light years. They calculated this number based on the age of the universe itself. The universe is about 13.8 billion years old. That’s when the Big Bang created everything we know and everything we don’t. So what happened next?

Using that 13.8 billion figure, scientists were able to construct the idea of a sphere around a central point that would be about 28 billion light years in diameter. If the universe were stationary, that would be the whole thing. But it’s not. It’s expanding. So some fancy math lets you calculate the size of the universe, assuming it has expanded following a constant all this time. That gives us 92 billion light years

All of those numbers are huge and impressive but it does beg one very simple question. What exists at 91 billion light years and one inch? That’s still the universe, right? Or what is about to become the universe as it expands. And then there’s another inch after that. And another light year.

There’s also the problem that expansion does not seem to be constant. Many scientists also believe the universe’s expansion is slowing down, which can throw the size off considerably. But the biggest problem in understanding the size of the universe seems to be that while it has a finite edge, because it has a starting time we can identify, it is expanding into infinite space. So the size of the universe beyond the observable may be impossible to calculate.

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