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epkid08
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As in, how does the universe expand, through another spatial dimension, etc?
epkid08 said:As in, how does the universe expand, through another spatial dimension, etc?
epkid08 said:It's true that the universe is 'apparently' expanding faster than the speed of light, right?
epkid08 said:It's true that the universe is expanding faster than the speed of light, right?
epkid08 said:If both an expanding universe and SR are correct,...?
I was simply saying that anything traveling faster than the speed of light, be it 2c or 3c, calls for an imaginary contraction/dilation.marcus said:SO THERE IS NO LENGTH CONTRACTION from the universe being in a moving frame.
and in fact what velocity would you propose to calculate a length contraction with?
the recession speeds of distant galaxies are all different---the rate of increase of the distance is proportional to the distance---long distances increase at a faster rate.
so there is no one speed that one can say the universe is expanding at this speed.
and even if there were, expanding is not moving.
I don't really understand this. The universe is making more space, and as it expands, our size in comparison to other masses stay the same, while our size in comparison to the universe gets smaller. How can it be stationary under these terms?marcus said:So the UNIVERSE AS A WHOLE IS STATIONARY from our point of view, and we are stationary with respect to it. that is after some corrections have been made for the sun's motion in the galaxy and the galaxy's motion in the CMB.
epkid08 said:I don't really understand this. The universe is making more space, and as it expands, our size in comparison to other masses stay the same, while our size in comparison to the universe gets smaller. How can it be stationary under these terms?
marcus said:I meant stationary in the sense of not moving relative to us. Growing of course but it's not as if it has a center of mass that is going right or left or north at 37 miles per hour.
When we are stationary with respect to the CMB we are at rest with respect to the universe and it is at rest with respect to us.
It is still growing of course. I didn't mean static. distances are increasing at a great rate.
wolram said:...Lambda is treated as normal energy/mass, has gravity, would that not be a problem?
Sundance said:G'dya from the land of ozzzzzzzzzzz
Its seems so logical the Big Bang Theory and the expansion and faster than the speed of light.
But! Something is missing.
Scientific evidence. If you can test it once and is able to be repeated time and time again.
Take any evidence and try to prove it.
Better still, by observations.
There is an abundance of precise direct and indirect observational evidence for both the BBN theory and superluminal recession of matter at large spatial distances. Is this what you meant? Check out Ned Wright's Guide http://www.astro.ucla.edu/~wright/cosmolog.htm and do a little reading, I assure you the evidence for each phenomenon is clear! Marcus could probably provide more direct links if you ask nicely...
Sundance said:I have not seen one observation that shows that super clusters are moving away from each other.
We cannot go to these super clusters to see things from their point of view, neither can we run tape measures to see if mutual distances between them are increasing, however under the Copernican principle, and given that further clusters do exhibit a greater red shift than nearer ones, (where the further galaxies subtend smaller angles), then it is as reasonable a conclusion that they are moving away from each other, as is the conclusion that local galaxies are moving away from the Milky Way.
The increasing red shift with distance of the light from these super clusters is the observation you are looking for.
The accepted theory on universe expansion is the Big Bang theory, which states that the universe began as a singularity and has been expanding ever since.
We know that the universe is expanding because of the observation of redshift in distant galaxies, which indicates that they are moving away from us at high speeds.
The expansion of the universe is caused by dark energy, a mysterious force that is thought to make up about 68% of the total energy in the universe.
No, the rate of expansion of the universe is not constant. It has been accelerating since the Big Bang due to the presence of dark energy.
Based on current observations and theories, it is believed that the universe will continue to expand forever. However, this is subject to change as our understanding of dark energy and other factors affecting expansion improves.