Light Breaks All The Rules - Beginners guide to Relativity Part 2

So this one is a bit dry but it gets us to the really cool stuff I promise!

Ok so if you remember my last blog post on special relativity and apologies for the delay, we talked about how there is no unique frame of references, every different type if valid and therefore the speed smoothing is moving can be very different depending on who is measuring it.

Soooo i lied to you a little bit. There is one thing that has a set speed no matter what you measure it and it is the speed of light.

So around the same time Einstein is coming up with his mind experiments on speed Maxwell is coming up with some equations to describe electricity, magnetism, space, time and the relationships among them. I won’t go into them but google them if you want, they are pretty cool ( cool being a relative term here). What these equations show is that when considering light in a vacuum a lot of variables drop off and you can work out the speed of light and it is constant and independent of the observer.

This kind of aligned with a thought experiment that Einstein did where he knew light was a wave ( it can also be a particle but that's for a different blog!) and he imagined going faster and faster and catching up with it when he tried to imagine it staying still in waveform it did not make sense, as if you caught up to the light it would be frozen in space from your points of view, but light be its definition (and oddly enough as defined by maxwells equations) so it had to be always moving from every observer's points of view.

I am not going to tell you why light acts this way because we don't really know it, just a fundamental property.

So this leaves us with two known things.

Light is the same speed for all observers,

however speed of all other things can be variable.

So lets imagine a quick thought experiment


You are sitting in an ocean sitting still and two beacons turn on in front and behind you. Because they are equal distance you see them reach you at the same time, lets say it takes 10 seconds to arrive.


Search and rescue have been tracking you via GPS and unknown to you you have been travelling towards one of the beacons very quickly because of swift currents, while you were between the 2 beacons when they flash by the time the light arrived to you you had moved towards one and way from the other, so the one in front of it takes only 8 seconds because you have closed the distance and the other takes 12 seconds because you have moved it way from it.

Since the speed of light is constant this leads to some very interesting and conflicting situations which leads us to one conclusion…

Time and distance are variable and dependent on the observer!

This will be the topic of our next blog!

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