As far back as you can remember, your teacher has always told you that the speed of light is constant and nothing, NOTHING, can go faster than the speed of light.

What if we told you that the speed of light isn’t constant? You might not be that shocked, if you have been paying attention in your secondary school physics class. Light travels at different speed through different medium. When light travels from air into water, it slows down, causing refraction – the bending of the ray of light. Light is only constant at the speed of 3 x 10^8 m/s when it is in vacuum.

But what if we told you that humans are travelling faster than light every day?

The slowest speed of light recorded is 61 km/h, a speed that you can easily beat when you get onto the expressway. Granted, light only becomes so slow when passing through rubidium cooled to almost absolute zero, a kind of Bose-Einstein condensate. But still, travelling faster than light? Cool (literally).

Which brings us to…

### How many states of matter are there?

3? Solid, liquid and gas?

4? Solid, liquid, gas and plasma?

Nope. It’s 5. Bose-Einstein condensate, solid, liquid, gas and plasma.

Bose-Einstein condensate (BEC) is a state of matter predicted by physicists Bose and Einstein in the 1920s but only proven to exist in 1995 when 3 physicists managed to cool rubidium down to almost absolute zero. For that, they got the Nobel prize in 2001.

Light slows down drastically when passing through BEC, as mentioned earlier. BEC also breaks the rule which states that electrons need to have opposite spins when they are in the same orbital. I bet even your JC chemistry teacher did not know that. But the coolest of all is that in this state, atoms begin to clump together, forming a single collective quantum wave. Instead of seeing discrete atoms, you see only one giant fuzzy ball.

### Wave-particle duality

What is cooler than an atom going from a particle to a wave? Well, it’s being a wave AND a particle at the same time.

Basically, electrons are supposedly indivisible bundles of matter. When being shot through a double slit, you will expect that electron to go through either one of the two slits and subsequently hit a point on the screen. Repeated over many times, two bands should form on the screen. However, the reality is, when the electron gets fired through the double slit, it exhibits wave like properties. It still hits a point on the screen like a particle but when repeated over many times, multiple bands are produced on the screen, which is a result of interference of waves.

What is even more amazing is that when you place a detector at the double slit to monitor the motion of the electron, the electron knows. The wave function then collapses, and the end result is no longer multiple bands indicative of wave properties, but two bands.

Mind-blowing? Wait until you hear about...

### The secret to immortality

The secret to immortality lies in Einstein’s theory of special relativity. To understand it, we will need a little thought experiment.

Suppose you are travelling in a spaceship at half the speed of light (without acceleration) and you shoot a beam of laser directly up towards a mirror. The laser bounces off the mirror and comes back down to strike a detector. From inside the spaceship, you can’t even tell that you are moving because the speed is uniform. But to an observer outside, the laser beam is observed to travel a diagonal path, and hence covering a greater distance. Herein lies a problem. The speed of light is constant. So how can light cover a greater distance in a same span of time to an observer looking into the spaceship? The answer is, it is not the same span of time.

c = d/t

Time moves more slowly in the spaceship. In the spaceship, a smaller distance covered is divided by a shorter span of time. As such, the speed of light c remains constant.

So what are the implications? The implications are if you go on a yearlong journey travelling at a fraction of the speed of light, time will move a lot slower for you. You won’t feel that the passage of time actually slowed, but when you get back from journey, your friends and family members would have aged decades whereas you are only 1 year older (a 1:10 ratio). The closer you get to the speed of light; the faster things speed up around you. The ratio might then increase to 1:100 or even 1:1000.

And what is the use of watching all your friends and family members die before you, while you embark on a lonely journey in space that from your perspective, lasts only 80 years before you die? Hmm… I also don’t know. But oh well, at least your enemies won’t be getting the last laugh.