Creating a FAQ: Questions about the Universe

[CosmicVoyager]

Greetings,

I see the same questions asked repeatedly (including by myself). It would be great if once a question is answered, it be added to a FAQ. A FAQ for each forum category.

Such questions include:

1) Does an object A moving relative to an object B exert a stronger gravitational pull on object B than if object A were at rest relative to object B?

2) If the answer to question 1 is yes, then the mass of an object increases with speed, correct?

3) If the answer to question 1 is no, then the mass of an object does not increase with speed, correct?

4) If mass does increase with speed, why?

5) If the mass of an object increases with speed, then the energy radiated from a moving object is greater, correct? The light radiated from a moving object is a higher frequency, correct? So the frequency measured would be a combination of that increase and the redshift or blueshift due to relative speed?

5) What makes the speed limit of the universe what it is?

6) Why does time move slower for higher speed objects? That is, why do processes occur slower such as clocks running slower?

7) Does the universe have an edge?

8) Does the universe have a center?

9) Is the universe finite or infinite?

10) Can the cosmic background radiation (CBR) be used as an absolute reference frame? Does the CBR appear blueshifted in one's direction of motion and redshifted in the other direction?

11) It is said that matter curves space. Illustrations show space around objects as a curved grid. This doesn't make sense to me because it has to be curved relative to something. Curved *relative to what*? The illustration shows the grid curved through space, so according to it space would require something else to be curved through.

 

[Fredrik]

There is a FAQ, but it's just a single thread that's incomplete and much too hard to find. What we need is a sticky FAQ thread at the top of each forum where it's a serious problem that people are asking the same questions over and over. The forums that need it the most are relativity and cosmology. The other forums can probably do without sticky FAQ threads, but these two can't, in my opinion. Every time I open the cosmology forum there's a discussion about the "center of the universe" or "before the big bang", and the relativity forum has many questions that are asked with an annoying frequency: The twin paradox, the photon's point of view, the mass of the photon, the very long rigid stick, Einstein's thought experiment involving a train and two lightning strikes, mistakes caused by not knowing the SR formula for addition of velocities, why can't you reach speed c, does mass increase with speed,... (I could go on).

This thread should probably be in the feedback section.

 

[bcrowell]

I agree that a sticky FAQ would be helpful, but writing one would probably be quite a difficult exercise in consensus-building.

I maintain my own FAQ here: http://www.lightandmatter.com/cgi-bin/meki?physics/faq

When questions come up that are on my list, I just cut and paste.