The Moving Universe

[sfphysics]

Resent studies show the universe is expanding at an accelerating rate, since our solar system is part of this universe how is it that we can see this movement? Shouldn't this movement be happening to us as well? Is it the slowness of light and the age old stars we are looking at in the universe expanding, or is the theory incorrect? Its like being in a car and driving down the road, the only way you know you are moving is if your surroundings are moving. If you block out your surroundings and only see a car next to you going at same rate, it seems as though you are at a stand still. Why aren't we expanding as well? Is there a possibility that we are, and we don't even realize it.

[Airbrush]

The universe is expanding at an accelerating rate only on the largest scales of structure. Superclusters of galaxies are moving away from all other superclusters of galaxies. Within a supercluster everything is gravitationally bound. The clusters of galaxies are bound by gravity to the other clusters of galaxies. Of course our galaxy is even more tightly bound by gravity. Stars are not flying out of the Milky Way into intergalactic space (except for binaries throwing an occasional star out into the abyss).

Edited April 27, 2011 by Airbrush

[sfphysics]

Okay, our galaxy is accelerating and super clusters threw out the universe are spacing out, yet it still does not make sense how we can See that. Our universe should be moving at all the same rate, as one whole. The car next to you can speed up a little bit faster than you but it only seems like the car shoved forward a few inches, and then continues to be at a stand still.

How is it that the large clusters can expand, and we see it as well, when the same is being done to us, again, is it the speed of light traveling threw the long distance of our universe to only show us the history, a ripple, in space/time or could the theory could be incorrect, we could be at constant motion and acceleration and see everything as a stand still until something moves a little bit faster in the past and we notice that ripple.

[Spyman]

When we look out into space it is not like Earth is a car on the street, it is more like we are on a boat in the middle of the ocean and all the other boats are accelerating away from us in all directions around us.

 

If we look at the Cosmic Microwave Background Radiation which is like an afterglow from the Big Bang, then Earth is moving with respect to the ocean with the speed of ~627 km/s.

 

When we measure the redshift of light from distant stars as a cosmological doppler, we notice that they currently recede from us with the speed of ~74 km/s/Mpc, the Hubble constant. Mpc stands for Megaparsec which is a distance of ~3.1×10¹³ km so the current value tells us that every second 1 meter is expanding with 74/3.1×10¹³= ~2.4 picometers and as comparison the smallest of all atoms have an estimated radius of 31 picometres.

 

As Airbrush are saying the acceleration of expansion is caused by a force called Dark Energy that actively tries to push the Universe apart, but on close range the nuclear forces or gravity are much much stronger and resists this force, causing objects to settle into equilibrium at undetectable but slightly larger size.

[sfphysics]

I see, interesting. And thank you.

[Airbrush]

Okay, our galaxy is accelerating and super clusters [throughout] the universe are spacing out, yet it still does not make sense how we can See that. Our universe should be moving at all the same rate, as one whole......

 

As Spyman says we see the spacing out by redshift of light from those distant galaxies. Hubble discovered that the farther away they are the more red shifted their light is.