Science fiction authors and readers dream of travelling at the speed of light, but Einstein tells us we can’t. You might think that’s an arbitrary rule, but [FloatHeadPhysics] shows a different way to think about it. Based on a book he’s been reading, “Relativity Visualized,” he provides a graphic argument for relativity that you can see in the video below.
The argument starts off by explaining how a three-dimensional object might appear in a two-dimensional world. In this world, everything is climbing in the hidden height dimension at the exact same speed.
Our 2D friends, of course, can only see the shadow of the 3D object so if it is staying in one place on the table surface, the object never seems to move. However, just as we can measure time with a clock, the flat beings could devise a way to measure height. They would see that the object was moving “through height” at the fixed speed.
Now suppose the object turns a bit and is moving at, say, a 45 degree angle relative to the table top. Now the shadow moves and the “clock speed” measuring the height starts moving more slowly. If the object moves totally parallel to the surface, the shadow moves at the fixed speed and the clock speed shadow doesn’t move at all.
This neatly explains time dilation and length contraction. It also shows that the speed of light isn’t necessarily a rule. It is simply that everything in the observable universe is moving at the speed of light and how moving through space affects it.
Doesn’t make sense? Watch the video and it will. Pretty heady stuff. We love how passionate [FloatHeadPhysics] gets about the topic. If you prefer a funnier approach, turn to the BBC. Or, if you like the hands-on approach, build a cloud chamber and measure some muons.
Since is movement relative to a fixed point and the fixed point is a matter of definition, can’t we define the fixed point to a photon? Would that make me moving at the speed of light ?
Massless particles move at the speed of light relative to everything else in all inertial reference frames, a photon as the reference frame is entirely nonsensical in modern physics.
You can, but remember that, then, all the universe (including you) will “look” as a single, 2D plane, without dimension in the direction of movement. That’s why, from the perspective of the photon, it can arrive at any point of the universe in no time.
Ops… this was an answer for 3eggert.
Mind blown! The next question where does everything travel to at the speed of light?
And where does the infinite energy come from to sustain speed of light? The universe would have to shrink, not expand.
Also you can only have speed if something stays behind, that would also mean infinite friction happening at that point.
You don’t need infinite energy to sustain that speed. You need energy to CHANGE the speed from the time dimension to the spacial ones, and vice-versa, and you need infinite energy to move ALL the celerity from the time dimension to the spatial ones.
The future.
What appears to be speeding up in space is actually just rotation of your 4D velocity into a more ‘spacey’ direction. You don’t notice the time dilation at ordinary speeds bc the necessary change in the 4D velocity direction is so small.