Expert: Tom Whiting - 3/4/2008

Question
I can't seem to find the answer for theys questions and was hoping you could help me with them.

1. Arrange the following from smallest to largest : glaxies, planets, superclusters, stars, clusters.

2. If we observe that all other galxies are expanding away from the milky way, does that mean that we are the center of the universe?

Thanks so much for you're help,

Answer

Hi Abigail,
Although it appears as a homework question, we're having a slow
day so I'll be glad to help you.
1. planets (Jupiter for instance ~ 88,000 miles), stars
(like sun at 865,000 miles) , clusters 'of stars' (in galaxy arms),
galaxies, and finally superclusters of galaxies.

2.  No.  It's like a loaf of raison bread rapidly rising (expanding) in the oven.  (The raisons are the galaxies).
On ANY raison, you'd see the same recession of all the other "raisons" and the more distant the "raison"... the faster it
would be receding from you...just like our Universe.
So any observer in ANY galaxy is seeing the exact same thing, the
same expansion as we are. So at present, there is no way to
determine who is....the "center" raison, if there even is one.

Realize that it's just the "space" that is expanding, not the
individual galaxies...and there aren't little "rockets" attached
to the receding galaxies; they are just "going along for the ride"
similar to an empty canoe down a mountain stream, going faster
and faster, because the expansion rate is actually accelerating as time goes by, according to the latest data of very distant Type Ia supernovae studies (1998).  (So the oven heat in our example above
is being continuously turned up to expand the raison bread faster and faster.) That appears to be the way the Universe is working.

Hope this helps,
Clear Skies,
Tom Whiting
Erie, PA USA

FOLLOW UP:
Thanks for the very nice comments and ratings;

Oh, "turning up the oven" was just meant for the raison bread
analogy, not the REAL Universe...hope you didn't think the Universe was heating up the same way, as it isn't.
In fact, it's been cooling down since the Big Bang of quintillions of degrees, down to the present day 2.73 degrees K above absolute zero, and getting still colder as time goes by.  In fact, some astronomers think that during the next 100 trillion years, the Universe will drop to 0.01 degree K Absolute, and eventually suffer a "heat death" as all the fuel, namely hydrogen gas, will be all used up by then. (AT an age of 'only' 13.7 billion years since the
Big Bang (like last month) we, the Universe, has only...just begun
last month, and the Solar System is only here 1/3 month (4.6 billion
years) on that same time scale....so the Universe has a long long
way to go....for instance, the little red dwarf main sequence stars have lifespans measured in several trillion years before they die out!! We have yet to see that happen to even one of them!
Clear Skies,
Tom