if the universe is expanding?

if you talk about red shift proving the universe is expanding surely we wouldnt see the reverse years after it started and if so is it possible that the universe has already stopped expanding and started going back

 

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i belive we would see blue shift i think but we would see this for some time after its started to go back

 

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Obviously we can't know the future, but up to now the universe has been expanding. Moreover, evidence found about ten years ago indicates that the expansion rate is speeding up. The universe could stop expanding tomorrow, but there is no physical reason for it. Until proven otherwise, we have to live with the expansion.

 

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I don't think we're going to be around long enough to figure that one out. But one thing is for sure, is that the galaxies are not moving away 'through' space, they are moving away 'with' space, as space itself expands.

http://archive.ncsa.uiuc.edu/Cyberia/Cosmos/ExpandUni.html

 

wow stephen! You are a smart 15 yr old.

 

Klitwo:

Your link was copyrighted in 1995. Much has been learned since then.

 

The same. Not much has changed. The universe is still expanding. Yawn:

http://en.wikipedia.org/wiki/expanding_universe

 

Yep, still expanding. Expanding forever. Galaxies still receding from us, moving through space [vacuum] away from us.

 

'Expanding', 'Receding' & 'Vacuum'. WOW! That's some pretty heavy stuff you're talking about here. You better publish this stuff someday. Science needs to know.

 

Walter has a theory that objects are hurtling through space with MASSIVE kinetic energies, the further they are, the more kinetic energy, hence their redshifts.

 

Q:

Just for fun, why don't you calculate how much potential energy a typical spiral galaxy has in the form of energy that was converted into mass during the BB [primarily energy converted into protons, and some deuterons and Helium nuclei], using E = mc^2.

Then, calculate how much kinetic energy that same nearby receding spiral galaxy would have, IF its recessional velocity were due to recession through space, using E = 1/2mv^2 [we'll stick with the nearby galaxies at first, as the relativistic effect is minimal].

Then compare, and tell me why you are "astounded" [which I presume is the case, because you always use CAPS when referring to "massive energies"] that so much energy could be converted into mass [mostly in the form of protons], but only a tiny fraction in the form of kinetic energy due to its recession from us.

Regards,


Walter

-------------

 

Gee Walter, I didn't know you were comparing apples to oranges in your theory. That could be part of your flaws.

 

Hmm:

Does that mean comparing the energy converted into mass, compared to the energy converted into motion, is like comparing apples to oranges? You'll have to explain yourself a little better, I'm afraid, as I don't know if I got your "apples and oranges" analogy correctly. Why don't you just do the math, and see the results.

 

Actually, Fraggle, it's an interesting question, with interesting results. Allow me to do the math since no one else seems to want to.

Let us set the mass of a typical spiral galaxy as being "M". Let us use its recessional velocity as being 0.01 c, or 1% of the speed of light [fairly fast, but not fast enough for relativistic effects to have a significant effect on the outcome using Newtonian calculations for kinetic energy]. Of course, the galaxies still farther away are moving faster, and they would have greater kinetic energy, and those closer would have lesser kinetic energy, if the mass "M" is the same.

Thus, the kinetic energy of that galaxy, due to its recessional velocity away from the Milky Way, would be 1/2 M [.01 c]^2; or 5E-5 M c^2

The potential energy, in the form of energy converted into the mass of the galaxy, would be simply M c^2.

Thus, we see that the kinetic energy of recession is actually only a very tiny portion of the energy of the entire galaxy system, with most of it being in the form of energy converted into mass.

I believe that that simple fact might be instructive for any of the 15-year-olds who log in here.

Regards,


Walter

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Mr. Wagner, assuming your math is correct, so what?

Moving objects carry a great deal of kinetic energy. Which means...?

 

Archie: Go back and read post #10.

 

Okay... presuming Q is correct, your theory is galaxies show up as red shifted because of their enormous kinetic energy and not as a result of the galaxy in question moving away from us at great speed?

Is that it?

 

E = Mc^2 is the rest mass energy of a particle. This is relativity, and does not have anything to do with a moving galaxy, which here is considerd to be a particle of mass M. Anyway, space is expanding, taking the galaxies with it, galaxies are not hurdling through empty space as such.

Redshift only occurs when objects are moving away from each other.

 

Archie:

No, galaxies show red-shift because of their recessional velocity.

Q believes that the recessional velocity does not mean they have kinetic energy relative to earth [Milky Way] due to that recessional velocity, because he says the recessional velocity is an 'artifact' of the expansion of space, and that the galaxy is just being 'carried along' by the expansion, and does not have kinetic energy due to its recession from earth [Milky Way].

Earlier, I posited a 'thought experiment' that a rocket ship sent from earth through that galaxy and onwards would have kinetic energy [relative to earth], so why would that galaxy not have kinetic energy.

Anyway, the idea in this thread is that, IF it does have kinetic energy, that kinetic energy is only a small portion of its total energy, with most of the energy of the galaxy being in the form of mass [proton mass primarily]. This was shown for only the nearby galaxies, where we can neglect the relativistic effect due to the relatively low recessional velocities.