If the big bang happened 13.8 billion years ago, and the universe is 93 billion light years in diameter, how did the universe expand faster than light?
In: Physics
13.8 being the radius of a circle. Times 2 for the diameter. Times 3.14 for the circumference. Equals 86.66. Pretty close for simple math. Seems legit.
The real answer: we don’t know.
The theoretical answer: It’s not the 2 balls on a fabric that’s accelerating.
It’s the fabric itself expanding.
WE can’t travel faster than light because of physics and matter, but space itself does not have those limitations.
This is probably the most asked question on this sub.
Relativity only applies locally. There’s no rule about how fast incredibly distant objects can move relative to each other, and it’s not a true velocity. Which is why people say “the space between objects is getting bigger” and such.
I’m just postulating here, but if you start light out at a point, and you have 2 rays going in opposite directions, then the distance between the edges of them is getting larger by two times the speed of light. That is absolutely NOT how the universe expands, but it does show that shit is relative.
basically the speed of light is the speed limit for “information” to travel through the universe. Think of it as anything that could be measured is considered “information”
Space itself is nothing, so it doesn’t count as “information” and can then pass the speed of light.
Another example is if you take a giant pair of scissors with light-year long blades. If you close the scissors at any speed where it takes less than a year to close, then the point where the blades touch will move along the blades faster than the speed of light.
The point itself is not anything that could be measured so it is “informationless” and can pass the speed of light”
I don’t know how much that helps, it’s how it was explained to me though.
Space itself is expanding. Nothing can move through space faster than light. But space can do whatever it wants.
Nothing can travel faster than light. But expansion is not travel. Galaxies, clusters and superclusters are not (generally) traveling away from each other, the space between them is just getting wider.
Draw some dots on a deflated balloon, then put some ants on the balloon. The ants can move at some max speed, which we’ll call C, and they walk between the dots because they’re made of food.
Now start inflating the balloon. If you do it fast enough, the distance between an ant and the next dot will increase rather than decreasing, even though they are walking towards the dot. The space between the ant and the dot is expanding faster than C.
Now imagine the surface of the balloon is 3 dimensional, and that it is expanding along a fourth dimension. That’s how the universe expands.
Imagine two cars accelerating in opposite directions from one another at equal speed. Imagine they both travel for one mile and then stop. The distance between the cars is now two miles. The speed at which the distance between the two cars increases is twice as fast as the speed of either car individually.
The same thing is happening with the Universe. It’s not that the matter itself is travelling faster than light; it’s that the matter at one end of the Universe is accelerating away from the matter at the opposite end faster than light itself can travel through space.
Imagine the universe like the surface of a balloon. This universe has an incredibly slow speed limit of 1 centimeter per hour over its surface. The balloon is also inflating so that two dots that are sitting still on the surface are actually moving apart faster than 1 cm per hour.
That’s what the universe is doing, except in 3 dimensions instead of 2. The really crazy thing is that the expansion is *accelerating*, and we don’t know exactly why.
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