cosmos

[unnoticed oracle]

whats the cosmos and everything we know and have thought of even in? and were does it exsist in?

[csmyth3025]

whats the cosmos and everything we know and have thought of even in? and were does it exsist in?

Another term for the cosmos and "everything we know and have thought of" is the universe. It all exists in the universe because, by definition, the universe is everything there is.

 

The portion of the univere that we call the observable universe is a spherical volume of the cosmos surrounding the Earth and limited to a present radial distance of about 46 billion light years. We can't see anything more distant than something whose light has been traveling to us for about 13.7 billion years (the age of the universe).

 

The expansion of the universe has increased the distance between us and these ancient regions of space when (and where) the light was first emitted by a factor of about 1090. These ancient regions were much closer to us when they emitted the light we're just now seeing - about 42 million light years away. These same regions are now about 46 billion light years away from us.

 

The light we see from these regions is called the cosmic microwave background (CMB).

 

It is generally believed that the entire universe is a lot bigger than out observable universe. It may be infinite - but so far there's no way we can tell for sure if it is or not.

 

More information can be found in the Wikipedia article on the universe here: Universe

 

Chris

[pantheory]

unnoticed oracle,

 

...and where does it exsist in?

I believe the best way to explain the containment of the universe is that it is a characteristic of the universe itself, such a question would be "what exists beyond the containment or the universe" Such a question would have no more meaning than what exists beyond reality? If there is just a single universe, then to say "where" is it? the answer accordingly is: There is only one place where the universe can exist and that's the only place where it does exist since there would be no other place.

Edited July 10, 2011 by pantheory

[BJC]

unnoticed oracle,

 

I believe the best way to explain the containment of the universe is that it is a characteristic of the universe itself, such a question would be "what exists beyond the containment or the universe" Such a question would have no more meaning than what exists beyond reality? If there is just a single universe, then to say "where" is it? the answer accordingly is: There is only one place where the universe can exist and that's the only place where it does exist since there would be no other place.

That is a philosophical answer.

 

Classical (Newtonian) physics, special relativity, quantum mechanics, etc. all postulate the existence of space and time. General Relativity postulates the existence of matter (mass, energy) and derives space and time - but we always use derived metrics which presuppose Minkowski space-time.

 

It seems physics theories require space and time to exist --- so the question "where does it exist in?" is a reasonable question --- and it is reasonable to assume that the "universe exists in this space-time" ??? :(

[pantheory]

That is a philosophical answer.

 

Classical (Newtonian) physics, special relativity, quantum mechanics, etc. all postulate the existence of space and time. General Relativity postulates the existence of matter (mass, energy) and derives space and time - but we always use derived metrics which presuppose Minkowski space-time.

 

It seems physics theories require space and time to exist --- so the question "where does it exist in?" is a reasonable question --- and it is reasonable to assume that the "universe exists in this space-time" ??? :(

O.K. if you insist

Edited July 11, 2011 by pantheory

[between3and26characterslon]

whats the cosmos and everything we know and have thought of even in? and were does it exsist in?

 

If it existed in something we would then have to explain where the thing we existed in existed in itself. It would be turtles all the way down!

[pantheory]

If it existed in something we would then have to explain where the thing we existed in existed in itself. It would be turtles all the way down!

 

Them turtles sure get around

[Airbrush]

".....The expansion of the universe has increased the distance between us and these ancient regions of space when (and where) the light was first emitted by a factor of about 1090. These ancient regions were much closer to us when they emitted the light we're just now seeing - about 42 million light years away. These same regions [CMB] are now about 46 billion light years away from us...."

 

Chris

 

Interesting thought. Does this mean that 380,000 years after the Big Bang, when space became transparent, the "edge" of the universe was 42 Million light years from the center of the expansion?

[imatfaal]

Interesting thought. Does this mean that 380,000 years after the Big Bang, when space became transparent, the "edge" of the universe was 42 Million light years from the center of the expansion?

 

No - it means that the universal expansion means that it has taken 13.7 billion years to cross a gap that if the universe were static would have taken 42 million years. There is no centre of the universe. If you go about 42 Gly away from earth (in any direction) - an astronomer at that spatial point looking towards the milkway will, at present be able to detect cosmic background radiation that was emitted in the era of last scattering from the region of space that went on to form the milky way. The radiation that alien astronomer detects will have travelled for 13.7ish billion years and crossed a distance that was 42 Mlyr and is now 46 Glyrs - ie exactly the same as us.

 

Everywhere sees CMBR at a distance of about 46 Glyrs and redshifted by over 1000 times what ever direction they look in. There is no centre

[Airbrush]

Imatfaal: ".....The radiation that alien astronomer detects will have travelled for 13.7ish billion years and crossed a distance that was 42 Mlyr and is now 46 Glyrs...."

 

Does this mean that it took the Big Bang 380,000 years for the observable portion of the universe to expand to a size with a radius of 42 Million light years?

 

If everything was together at the moment of the Big Bang, then after 380,000 years of expansion the distance between our position in space and the edge of our observable universe grew to 42 Million light years.

Edited July 14, 2011 by Airbrush

[imatfaal]

At 380000 years (aside from the fact that the universe was opaque before last scattering and dark afterwards - thus no observations either way) the portion of the universe that we observe today had a radius of about 42Mlyrs.

 

"If everything was together..." that implies an explosion from a point into space, this is not what is thought to have happened. Everywhere and everything started expanding rapidly space included. but otherwise yes, at 380000 years what is now the area of space (from which the cmbr we currently observe was emitted) was 42Mlyr

[Airbrush]

Then is it correct to say that from a point source to the edge of our observable universe, at 380,000 years after the Big Bang, is a radius of 42 Million LY. This implies at average speed of expansion of 42 Million LY in 380,000 years, or 110,526 LY per year, or 303 LY per day, or the faster-than-light speed of 12.6 light years per hour!

[imatfaal]

Universal expansion can be greater than the speed of light as nothing is travelling through space - it is space itself that is expanding. It is fairly simple maths to find the required seperation of galaxies today for which the gap is growing faster than the speed of light.

[csmyth3025]

Then is it correct to say that from a point source to the edge of our observable universe, at 380,000 years after the Big Bang, is a radius of 42 Million LY. This implies at average speed of expansion of 42 Million LY in 380,000 years, or 110,526 LY per year, or 303 LY per day, or the faster-than-light speed of 12.6 light years per hour!

Imatfaal is correct that Special and General Relativity place no limits on the rate at which space itself expands.

 

Your calculation of the average rate of expansion is somewhat off the mark:

 

[math]\frac{4.2\times10^7\,LY}{3.8\times10^5\,yr}=110.526\,LY/yr[/math]

 

This doesn't really change the validity of the point you're making, though - as long as you realize that the rate of expansion was much greater than this average value at times very close to the big bang and much less than this average value at the time of recombination (~380,000 years after the big bang).

 

Chris

 

Edited to correct spelling erreor

Edited July 18, 2011 by csmyth3025