What is the Colour of an Atom? - And the Galaxies Going Faster Than Light

A short film exploring the dual nature of light, spectroscopy, perception and the sad truth about astronomy. May or may not contain a pun. (It does.) 

What it certainly doesn't contain is an unexpected fact about rainbows, the truth about the empty floating bit of nothing between the wood and the fire itself and the story of the galaxies travelling faster than light. Because they are in this here blog post.

In September 2017, I found out there existed a competition called the Breakthrough Junior Challenge aimed at young science video makers. Only the deadline was really soon. What followed was a frantic week and a half of researching light, which is super weird, makes its own rules and doesn't take shit from anybody, as well as all other work that went into the film above. Because the film had to be 3 minutes max, a lot of incredible material didn't make the cut. So it colonised this post, in a sort of list format, below.

- A guy on Reddit made a comment I found, while not precisely correct, a brilliant perspective: "Mass is basically the ability to not travel at the speed of light."

-All photons are not born equal! The photon model entails that each photon has its own individual frequency, according to its energy. (This is a misconception I was under before, so I figured what the hell, maybe there are people out there as stupid as me.)

-Obvious, but still interesting: if you could see using radio waves instead of visible light, walls would be transparent. You would need huge eyes in order to see radio though.

-Time dilation is a basic phenomenon in the Theory of Relativity. In a nutshell, it means that things going slower than you experience time more slowly, while those going faster experience time faster than you. You can't feel the effects at normal speeds, but at speeds closer to light it gets intense. One example is what's known as The Twin Paradox: one twin stays on Earth, while the other gets on a spaceship and travels around space at close to light speed for a couple of days. When the twin returns, a few decades have passed on Earth and he finds his own twin far older than him.

While amazing, this isn't exactly fresh news. What piqued my interest is a consequence of this I stumbled on: The faster you accelerate, the less time passes from your perspective. And you get closer and closer to light speed, and time goes slower and slower... and then it stops. At light speed, no time passes at all. From light's perspective, it gets anywhere it's going in an instant. There is no time. It seems a bit sad to think that, even though all life depends on it, light barely even exists as far as it is concerned.

-On the same topic, it's worth remembering that "light speed" is shorthand for "light speed in a vacuum", because, as W. Harris and C. Freudenrich point out in their HowStuffWorks article:

"We've always taken for granted that light travels faster than anything in the universe. Then, in 1999, researchers at Harvard University were able to slow a beam of light down to 38 miles an hour (61 kilometers per hour) by passing it through a state of matter known as a Bose-Einstein condensate. That's almost 18 million times slower than normal! No one would have thought such a feat possible just a few years ago, yet this is the capricious way of light. Just when you think you have it figured out, it defies your efforts and seems to change its nature."

Image by Steve Krave

-Things with temperature emit light. That's how they give off the extra heat. If possible. Your body, for instance, as well as everything warm to the touch, gives off infrared light we can't perceive.

-Warm and cold colours are exactly the wrong way around. Red is a less energetic colour of light than orange, which is less energetic than yellow, which is less energetic than... green, then blue, indigo and, most energetic, purple. That means that if you take a lump of iron and heat it up, it'll first glow red-hot, then orange, then, as it gets even hotter,... it'll in fact start emitting all visible frequencies and thus glow white, because it doesn't heat up uniformly. But if it did heat up uniformly, it'd fade to green, to blue, to purple. Also, blue fire is hotter than orange fire.
Orange is the cold colour. Blue is the warm colour. Think about it.

-What happens when you light a candle is that the wick heats up and turns into gas, but the reaction is of such nature that it doesn't stop there and grows even hotter. What you see as the flame is in fact ionized gas that's so hot it emits photons (the molecules have to get rid of the extra energy somehow). If you look closely, though, there is a small aura of nothingness around the burning wick, between it and the flame. That is freshly formed gas that hasn't heated up to a glow just yet. So it's transparent.

-Glow-in-the-dark deep sea fish usually give off blue light, because that's the colour that propagates the farthest in water.

-In 2009, the World Health Organization labeled tanning beds "carcinogenic to humans". Sadly predictable.

-White T-Shirts glow under a black light because detergents contain phosphors that hang on to your clothes. As far as I'm aware, they aren't toxic, but they glow white when struck by UV radiation, which is what black light is.

-Albert Einstein didn't get a Nobel Prize for his Theory of Relativity. He got it for getting physicists to think of light as both a wave and as made up for photons. The prize was stated to be awarded "for his services to theoretical physics, and especially for his discovery of the law of the photoelectric effect."

-About one-fifth of your brain does nothing but try to deal with the visual world around you.

-All our Earthly shadows are actually a bit lit up by light reflected from gases in the atmosphere. Only shadows on the Moon are completely dark.

-All rainbows are double, and we've known about this at least since the ancient Greeks. The secondary rainbow is fainter, mirrored and parallel to the main rainbow. The dark gap inbetween is called Alexander's band.

Photo by Sorin Nechita

-Finally, the fact that blew my mind to the edge of space and back: the leading edge of the Universe as it's expanding is in fact moving faster than light. Even some distant galaxies are moving away from us at speeds greater than that of light. And here I was, silly me, thinking c is the top speed in the Universe, as physics appears to state.
In fact, that's perfectly alright. Relativity is a sneaky bitch. You see, Special Relativity states that nothing can ... "locally" go faster than light. General relativity allows this to happen over really vast distances. It doesn't break any rules. It's true that nothing can go faster than light. But what's happening is space expanding this quickly, and, luckily, space is literally nothing.

Or, as a friend on a forum put it: "Imagine you have two balls on a tarp, right? They can't reach light speed, but somebody's playing silly buggers and stretching the tarp faster than light."