How much hydrogen and helium does it take to make a -

reply to post by jiggerj


related to that image and idea,,,,,, would there be a gigantic "empty area" in the middle of the universe where the singularity occurred?

Originally posted by jiggerj
Is anyone claiming that this is the edge of our universe and that there is nothing beyond it?

The CMB is not coming at us from any source. It pervades the whole universe.

Originally posted by ImaFungi
Would there be a gigantic "empty area" in the middle of the universe where the singularity occurred?

No.

Further elaboration (of both answers) below.

*

In its very early stages, the universe was mostly hydrogen, and it was dark. It was not until a million or so years later (numbers vary), when the first stars began to shine, that light dawned on the universe. The first light in the Universe

During these 'Dark Ages' the universe was expanding amazingly fast – much faster than the speed of light. This we call inflation. The reason space can expand faster than light is that space is not matter; only material substances are speed-limited by relativity.

If the inflation hypothesis is correct, then the most distant parts of the universe are still travelling away from us at this speed, carrying away with them the stars, galaxies, etc. they contain. The light from these objects will never reach us; they have always been invisible to us, and forever will be.

But later in the history of the cosmos, the acceleration slowed drastically. This explains why the nearer (hence more recent) an object is, the more slowly it seems to be moving away from us.

The parts of the universe we can see are those moving away at speeds less than that of light. We call this volume of space the 'observable universe'. The oldest and farthest objects in it are 13.7 billion years old, but their distance from us is much greater – about 46.5 billion light-years. This is due to the expansion of space described above. If space had not been expanding, the farthest objects we saw would still be only 13.7bn LY away.

The expansion of space also 'stretches' the light from the most distant visible objects so much that they appear to us as long-wave radio signals. Ancient Radio Waves Hold Key to Universe's First Light This phenomenon is known as cosmological redshift and is different from the Doppler redshift with which most people are familiar.

But the visible universe isn't the whole universe. Inflation implies that the cosmos almost certainly extends well beyond that 46.5bn LY visibility boundary. How much farther is unknown, since we have no way of accurately measuring or estimating the rate or duration of the inflation epoch. Indeed, the universe may, for all we know, be infinite (though most scientists think this unlikely).

What the invisible portion of the universe contains, how big it is and so on are things we shall probably never know. All scientific estimates of the size, mass, energy, etc. of the universe are concerned only with the 46.5bn LY sphere we call the 'observable universe'. Size of the universe

The expansion of space (both now and during the early inflation phase) was not expansion away from a central point. Space is expanding everywhere throughout its fabric, so every point in the universe is the centre. As far as we humans are concerned, Earth is the centre of the universe (no, really!) That is why the CMB seems to be coming at us from every part of the sky – and why it would look just the same to an observer in a distant galaxy, even (probably) one beyond the fringes of the observable universe.

Originally posted by Astyanax

Originally posted by jiggerj
Is anyone claiming that this is the edge of our universe and that there is nothing beyond it?

The CMB is not coming at us from any source. It pervades the whole universe.

AHHH! I did not know that. Thnx! When I think of 'background' I'm imagining something over there, not all around us. Learn somethin' new everyday.

Originally posted by jiggerj

Originally posted by Astyanax

Originally posted by jiggerj
Is anyone claiming that this is the edge of our universe and that there is nothing beyond it?

The CMB is not coming at us from any source. It pervades the whole universe.

AHHH! I did not know that. Thnx! When I think of 'background' I'm imagining something over there, not all around us. Learn somethin' new everyday.

Two physicists named Penzius and Wilson named it "background" microwave radiation because it was like a background upon which all other sources of cosmic radiation, whether visible or in the radio spectrum, was seen. They really weren't looking for it but found it accidentally while working on microwave "horns" for Bell Labs. They got this strange dim "buzz" regardless of where they pointed the antenna. At first they thought it was bird sh*t on the antenna (Sorry mods, but you have to put up with one bad word in the interests of scientific accuracy. They rigorously cleaned the horn but the signal was still there. And it was fairly isotropic.