Tuesday, 11 June 2013

10 most mind-bending physics facts

For some of us, physics was something we dreaded at school, abandoning our studies in it at the earliest opportunity, all before reaching adulthood and realising that this particular branch of science is arguably the coolest. Fortunately, there are graduates, postgrads and doctors who had more foresight than people like this humble writer and made the study of physics their life’s work. Here are some of the unbelievably cool things about physics that we have learned because of people like them.


1. Relativity Makes Space Travellers Younger (Kinda)

Both velocity and gravity have an effect on the speed of time; the higher they are, the slower time passes. Astronauts aboard the International Space Station (ISS) (who are in reduced gravity compared to people on Earth but travelling at increased speed around it) experience time more slowly, at a rate of roughly 1 second ‘lost’ every 747 days.

2. Without E=MC2 GPS Would Malfunction

e mc 2

The satellite navigation in your car or on your phone relies on a series of geostationary satellites to pinpoint your location, exchanging data using radio waves. Because of the theory of relativity, the speed at which the satellites’ onboard clocks tick is around 38,000 nanoseconds faster than clocks on the ground. Every time data is sent to the receiving device, a calculation must be applied to correct the timings to within the required 20-30 nanosecond accuracy.

3.’The Speed Of Light’ Isn’t Constant

speed of light

Most people will have heard about the speed of light (c. 671 million miles per hour), which according to all accepted laws of Physics is the fastest that anything can travel. In actual fact, this figure refers only to the speed of light in a vacuum. Really, light is slowed whenever it passes through something, being measured travelling as slowly as just 38 miles per hour at absolute zero (-273.15C) through ultra-cooled rubidium.

4. Humanity Could Fit In A Sugar Cube

sugar cube

Remember when you learned all about the basic structure of the atom – protons, neutrons, electrons? You might recall there was a lot of empty space, and you’d be right. Most of atoms is just empty space, so much so that if you gathered the entire human race together and removed the empty space of all the atoms that make them up you would be left with something no larger than a sugar cube. Incidentally…

5. That Sugar Cube Would Weigh Five Billion Tons

Why? Because all that empty space doesn’t have any mass, so the sugar cube of humanity would be extremely dense. It’s the same principle behind why 1kg of bricks and 1kg of feathers weighs the same, but a box of bricks is denser and has more mass than an equally-sized box of feathers.

6. We Don’t Know What Most Of The Universe Is

question mark

Despite all the advances made in astrophysics in recent years, not least the discovery of various exoplanets beyond our solar system, we don’t know what makes up the majority of the universe. It is possible to make reasonable estimates of the mass of the universe, except that visible matter (stars, planets, stellar objects) only accounts for 2% of that; what exactly makes up the rest – so-called ‘dark matter’ and ‘dark energy’ – remains a mystery.

7. Go Fast, Gain Weight

einstein funny face

Our old friend relativity explains this one as well – mass and energy are equivalent, meaning that as you add energy to a moving object (i.e. increase speed) then that object’s mass increases. At ‘normal’ speeds, this mass gain is pretty negligible, but as you approach the speed of light mass begins to increase dramatically. In case you’re wondering why sprinters and cars and aeroplanes don’t get heavier because of this, don’t worry – the increase in mass as a result of increased speed is only temporary.

8. You Could Be A Walking H-Bomb

hydrogen bomb

The First Law of Thermodynamics holds that in any situation, the total amount of energy in will equal the exact same amount of energy out. As well as meaning that you can’t create energy out of nothing, this law means that you also can not destroy energy. So what happened to all the energy that came from what you put in your own body? The short answer is that most of it remains stored within your body, an average of 7×1018 joules – this amount of energy, if released all at once, would have the same power as 30 hydrogen bombs.

9. You Might Already Have Read This

the big crunch

According to Big Bang cosmology, the universe is constantly expanding. One school of thought suggests that this expansion must eventually not only slow down, but also go into reverse and cause a ‘Big Crunch’. What would happen then is a mystery, but if there is indeed a cycle of ‘bang, expansion, contraction, collapse, bang’, it may well be that the universe plays out in exactly the same way. You might have been born, lived, read this article, lived some more and died in exactly the same way over and over again and not even know it.

10. Another You Might Have Died Reading This

parralel universes

 

According to the multiverse theory (yes, it’s not just a Family Guy thing), there are an infinite number of universes existing parallel to one another, with each differing slightly and every possible scenario being played out in its own universe. This would mean that in at least one universe, a freak accident meant that you were hit by a meteor and killed before finishing this sentence. In another universe, you wouldn’t have even read this article in the first place, because I would have been hit by a meteor and killed before finishing writing it. For a classic 90s TV take on this theory, go look up Sliders on Youtube