I have a question. Is distance a constant. I picture the universe expanding. The universe has an amount of mass that is constant. As the universe expands the amount of mass in that volume becomes less per any given area. If it didn't we would have areas of no mass. Does this mean I am expanding? Is my computer expanding also. If it is then the measurement devise I use would also would also be expanding. Which means that I wouldn't notice it. This would happen over a very long period of time and I know that It wouldn't be happening as I type this but I use that example to try to explain my thoughts.
As the universe expands does everything expand? Is it directly porportional to one another? From a subatomic level to the whole universe.
We had the big bang theory where everything was concentrated to a small point then bang the matter flew out everywhere, expanding, the distance between particles increasing. As this expands does it try to even out the areas of less density to reach equilibrium?
Also, If this is true how would it affect the theories of physics. If distance isn't a constant value the speed of light would change.

I don't have the time to really go into detail, but I will tomorrow, if noone else has.
but simply speaking, if the distance doubles then so will the speed of light, and so will the length of the "ruler" and therefore measurements will still say that speed of light is same.

Distance is a constant...especially for non moving objects. Everytime I have to walk a mile...it is still a mile....

Now to get to the country store for gas...that was 6 miles until it burned down last year and then rebuilt...now it is 6 miles and a tenth. And when I got gas the other day, it was still 6 miles and a tenth.

Now, if you have tires on your truck that are bigger than suggested, then that changes your ro0tations per minute and will change the distance back to 6 miles...

So, if you use the right tires when traveling the universe, distance is a constant...go up one size to get through the mud easier..and then it changes

My advice...stay with the recommended tire size when traveling through space and your distance thinag should be just fine...however, realize the objects traveling to are moving also..so you have to be traveling the same speed or faster to get there

Kind of like the difference between chasing down a horse in your truck vs chasing down a pig in your truck

Originally posted by jlafleur02

Does this mean I am expanding?

Expanding along which dimension?

The one's we can perceive or some other.

Expanding along all dimensions simultaneously? If so where is the distortion, and if no distortion is detected, what is the mechanism that causes uniform expansion.

Plants grow up, clouds expand out, the tide comes in and receeds.



But if you purely refer to the theory of the expanding universe, then maybe consider this. Red shift only suggests that most stars are moving away from us. Not all. Most. So even then, there is not a metric to show that there is either a fundamental expanding of reality or that the bodies in the universe are all moving away from each other uniformly.

Hope that helps.



David Grouchy

Ok I will agree I am wrong for now.
for part of it anyway.

This, really, is a high-level physics question that doesn't really have a firm answer.

It really depends upon what model you subscribe to, and whether we are talking in quantum terns or in relativistic terms.

In pure 'relativity' models, 'space' (also could be called 'distance') is capable of being distorted. This is one of the explanations given for gravitational lensing - that space can have different 'densities' and therefor have a refractive index. It is also speculated that space, can 'move' or expand-and-contract to propel the source of such a phenomena. This is the basis for the "warp" drive concept.

You could also render distance null if you figure that 'time' is somehow slowed by gravity, in which case - a beam of light can only travel so far in a given instance (which is the maximum speed at which information can be sent) - which means that the distance light travels is still the same - time is simply altered.

This is why space is often thought of as space-time - in relativity, the two are intrinsically linked from a macroscopic perspective (space appears more 'dense' around large gravitational bodies - but everything also appears to move slower, there - so the net effect from the perspective of any one entity is that distance is constant).

Again - this is purely theoretical. There are other models out there, most of which deal in terms of unified fields (quantum and relativistic models), that say space is the same density - or has no effective density, and the effects of gravitational lensing are due to the interaction of light and mass - not the interaction of light and space.

It's really not something we can test very well at our techno-industrial capabilities. We would need to be able to reproduce gravitational fields or perform experiments in much more extreme gravitational environments to be able to answer many of these questions. Although it is possible for other discoveries in physics to 'trickle' across and limit the number of possible scenarios - it will not be the 'magic answer' we are looking for.

You would have to look at posts by other members or in physics forums/discussions to look at the question of distance constants in quantum models - and into what more recent studies have found.

After thinking about all the responses, Which are great and I appreciate it, distance would be measured from point a to point b. If the universe is expanding then the distance would be over an arced line. Does this mean nothing truelly goes in a straight line?
If so then wouldn't the line eventually end in a circle?
Would this mean that no matter where you started from you would eventually end back where you started from?

It seems to me nothing goes on forever and I always thought that the end of the universe going "north" would bring you to the south end, not out forever. Hard to wrap my head around it.