h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

how much of the universe can we see from earth and the space around us


Taff
agent of kaos

Traveller in Time looking up
"All I can see are clouds . . .


Look at the pictures posting 9 and 11. As far as known the same object.

The background stars are of non importance to the comet, There are many in visible light.
There are many more over the entire spectrum.

We can calculate the non radiating objects by their mass influence on nearby objects.


I have a calculation in my mind two digits in a simple expression.

The first digit is 4. Can you know the answer when I am not telling right or wrong ? "

I´m guessing you are referring to Dark Matter. Well, this isn´t about how far out we can see. It is about how there seems to be something in the universe that we can´t see, but which has a gravitational effect on objects. For example if you look at a galaxy, the speed it is spinning at, the gravity of the stars should not be enough to keep it from being ripped apart. It seems there is some other kind of matter in the galaxy which exerts a gravitational attraction on the galaxy to help keep it together. Calculations indicate that as much as 90% of the universe could consist of this Dark Matter, which we can´t see.

The question could also be how much of the universe within the visible universe, regardless of whether we can actually detect it. Well, it seems that we can see for 14 billion light years, although that's misleading because the stuff from, say, 10 billion light years away is also from 10 billion years ago when the universe was much smaller.

Erm. I guess we need to know how big the whole universe actually is.

As big as you can possibly imagine and add 1m^3...


and again...


and again...


and again...


You get the drift I hope?

Yes the light from the matter we can see at the very edge of the visible Universe is about 13.7 billion years old and (important idea coming!) WHEN IT SET OFF the Universe was a lot smaller but still pretty much infinite in size compared to it's first moments.

Take a look here (takes a deep breath and posts a link to W*k*p*d*a) http://en.wikipedia.org/wiki/Cosmic_inflation

turvy