Recent content by zbe

If I understand OP's reasoning, an analogous example would be comparing heights of two persons. Say person A is 2.00 m tall and person B is 1.50 m, so clearly person A is taller. But now we re-calibrate person B's meter so 1 meter = 1.33 meters and we conclude that, in fact, both persons are of...

This reminds me of a clip of Brian Greene on The Big Bang Theory. :-p

What? :o --- You still can't grasp that velocity is a relative quantity. Do you understand that you are traveling at this very moment at 0.9c relative to some star in our universe? And you are also traveling at 0.5c wrt to some other star. And you are also traveling at 0.8c wrt to some...

"Through space" is invalid definition. You are always measuring velocity with respect to some other object. So how could you possibly know that you are moving if the spaceship was the only thing in space? You couldn't and that's the whole point. The rest of the post is irrelevant - you can do...

Relative to what? Close to c relative to what? You specified it is bolted to the floor. So it is stationary wrt to the 2nd ruler (before 2nd ruler is thrown). Also "shrink" isn't really appropriate word IMHO. Its length contracts in the direction of motion. It doesn't because you are...

You can't travel at the speed of light. You can get arbitrary close to it though. You are missing the point that speed is relative. With respect to Bob, the ruler will travel with whatever speed he throws it. It doesn't matter if Bob is in a train, in a hotel or in a spaceship - as far as he...

Can you/someone explain this in more detail?

Reading this thread just makes me nervous. And sad.

By "open" and "closed" (or flat) I mean the curvature of the universe. And (on page 3 or 4) it was said that only closed universe would "guarantee" finite space --- but it looks like it is infinite since we most likely live in a flat universe. I think that all our knowledge ATM goes towards...

Hi everyone. I have a question. As already mentioned the measurments tell us the universe is flat or nearly flat. It was also stated that only closed universe would be spatialy finite and both the open and flat one would be infinite. My question is: How can universe have a beginning and is...