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Who has a problem with the current cosmology?

 


stone1343
I'm not saying I have a better understanding than so many great minds that have put together today's theory of cosmology. However, it just doesn't make any sense. I'm sure I have some of the details wrong, but I think the gist is correct.

Some of the things I just don't get:
The expansionary universe. In some infinitessimal fraction of a second, the universe goes from being the size of a grapfruit to the size of the Milky Way. And this is propsed because it makes the equations work?

Dark matter: They say there must be dark matter because there's not enough mass in the stars we can see to account for galaxies not flying apart. How do we know in the first place how many stars are in a particular galaxy? The obvious answer to me is: Galaxy X is spinning at such-and-such a rate, and therefore must have such-and-such a mass. Well maybe that really is the mass of the galaxy, just with the regular matter.

Dark energy: Even worse, they say the rate of expansion of the universe is speeding up because more distant supernovae are dimmer than they expect. This is the way I've understood the argument, but it it not possible that it's intergalactic dust that makes supernovae dim?

Of course it doesn't make sense that we would be in the exact center of the universe, but how else do you explain that galaxies in all directions are moving away from us? I once did some basic 2-d calculations (even thought I've forgotten all my high school math) and it at least seemed possible to me that a universe where there truly is a center and everything is receding from it, at a speed proprotional to the distance from the center, it would look to an observer at any point like everything was uniformly receding from him. Along the x-axis it would look like this:
Center of the universe is at 0, and there are stars at 1 and 3. Observer is at 2. So star 1 is moving away from 0 at vx, 2 is moving at 2vx, 3 at 3vx. For the observer at 2, the stars at 1 and 3 are equally far away from him and both moving away at vx.

Comments?
The Conspirator
Some things you got wrong.
Quote:
In some infinitessimal fraction of a second, the universe goes from being the size of a grapfruit to the size of the Milky Way.

No, it took a a lonng time for it to expand that much.

Quote:
Dark matter: They say there must be dark matter because there's not enough mass in the stars we can see to account for galaxies not flying apart. How do we know in the first place how many stars are in a particular galaxy? The obvious answer to me is: Galaxy X is spinning at such-and-such a rate, and therefore must have such-and-such a mass. Well maybe that really is the mass of the galaxy, just with the regular matter.

I'd say something but I know I'd get some things wrong.
http://en.wikipedia.org/wiki/Dark_matter

Quote:
Dark energy: Even worse, they say the rate of expansion of the universe is speeding up because more distant supernovae are dimmer than they expect. This is the way I've understood the argument, but it it not possible that it's intergalactic dust that makes supernovae dim?

No, there is dist out there but its far apart, too far apart to have the effect of dimming light from distant galaxy's and the dust is contained in nebula's.

Quote:
Of course it doesn't make sense that we would be in the exact center of the universe, but how else do you explain that galaxies in all directions are moving away from us?

We are not in the center, the universe is expanding, the universe is flying apart thus the clusters of galaxy's get further and further apart from each other.


Your questions can be answered here.
Bikerman
stone1343 wrote:

Some of the things I just don't get:
The expansionary universe. In some infinitessimal fraction of a second, the universe goes from being the size of a grapfruit to the size of the Milky Way. And this is propsed because it makes the equations work?

You have not understood inflation. It does not propose what you seem to think.
http://en.wikipedia.org/wiki/Cosmic_inflation

Quote:
Dark matter: They say there must be dark matter because there's not enough mass in the stars we can see to account for galaxies not flying apart. How do we know in the first place how many stars are in a particular galaxy? The obvious answer to me is: Galaxy X is spinning at such-and-such a rate, and therefore must have such-and-such a mass. Well maybe that really is the mass of the galaxy, just with the regular matter.

We know by observation. Detailed surveys have been done of several galaxies using normal teloscopy.
http://nedwww.ipac.caltech.edu/level5/PROPERTIES/dog.html
Quote:
Dark energy: Even worse, they say the rate of expansion of the universe is speeding up because more distant supernovae are dimmer than they expect. This is the way I've understood the argument, but it it not possible that it's intergalactic dust that makes supernovae dim?

No. It is nothing to do with 'dimness'. The metric which is most important here is the cosmological red shift - an effect analagous to doppler shift in audio waves. I wrote a paper for the lay-person a while ago on this and it may be helpful.
http://camres.frih.net/resources/GeneralPhysics/universe-guide/universe-guide.htm

Quote:
Of course it doesn't make sense that we would be in the exact center of the universe, but how else do you explain that galaxies in all directions are moving away from us? I once did some basic 2-d calculations (even thought I've forgotten all my high school math) and it at least seemed possible to me that a universe where there truly is a center and everything is receding from it, at a speed proprotional to the distance from the center, it would look to an observer at any point like everything was uniformly receding from him. Along the x-axis it would look like this:
Center of the universe is at 0, and there are stars at 1 and 3. Observer is at 2. So star 1 is moving away from 0 at vx, 2 is moving at 2vx, 3 at 3vx. For the observer at 2, the stars at 1 and 3 are equally far away from him and both moving away at vx.

No. This is a misunderstanding of the basic topology involved.
The classic analogy is to imagine spacetime as the skin of a balloon. As spacetime expands the skin of the balloon expands. Imagine the galaxies as drawings on the skin and you will see that for any point on the skin, all other galaxies are receeding from that point. The paper I mentioned above may be helpful here as well.

Regards
Chris
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