Expanding Universe : All the way down to atoms?

[rogerinnh]

Many of the descriptions that I have seen explaining how the universe is expanding describes the galaxies as "riding along on the expanding universe". The descirption seems to indicate that, although the universe itself is expanding, each galaxy itself is not.<br />So, my question is this, Does the expansion of the universe extend all the way down to galaxies, solar systems, planets, and even to atoms, or is it something that applies only on the largest scales? If I had an accurate enough measuring device could I measure the expansion of the universe by watching a single atom slowly get larger?

 

[odysseus145]

Here's an article from a while back about the universe's expansion. <div class="Discussion_UserSignature"> </div>

 

[Maddad]

RogerInNH<br />We had a thread some months back discussing this idea. The amount that space expands depends on how much space you start out with. The Hubble Mostly Constant says that a megaparsec of space will expand by about 55 kilometers in one second.<br /><br />A megaparsec though is a long walk down the road. The parsec (paralax second) is about 3.3 light years, so the megaparsec is 3,300,000 light years. Since the light year is 10,000,000,000,000 (10 trillion or 10¹³) kilometers, a megaparsec would be 33,000,000,000,000,000,000 (33 billlion billlion or 33 x 10¹⁸) kilometers. In one second this distance will increase by 55 kilometers to 33,000,000,000,000,000,055 kilometers.<br /><br />That ain't much of an increase.<br /><br />If we divide the megaparsec by 55, then we can say that 600,000,000,000,000,000 (600 milllion billlion or 600 x 10¹⁵) kilometers of space expands one kilometer in one second. Dividing by 1,000 to convert to meters, we could say that 600 x 10¹⁵ meters of space expands one meter in one second.<br /><br />How much though does one meter of space expand in one second? We divide 1 by 600 x 10¹⁵ to get about 1.7 x 10^-18 meters. In about half an hour the space that your meterstick used to occupy will expand by the diameter of a proton.<br /><br />This however does not mean that your meterstick will expand by this distance, just the space that it occupied will expand. As soon as your meterstick thinks about going for a stroll, the electromagnetic force coralls it back into shape.<br /><br />Since the electromagnetic force is millions of times stronger than the expansion of space force, the expansion of space would have to millions of times greater before your meterstick comes apart at the seams. The Hubble Mostly Constant would have to be millions of times greater than it is now. That might happen; but I won't be here to post about it.