Why is space accelerating?

[Saslou]

Please excuse my ignorance .. I know very little about this subject so this is why i am asking the following questions.

I have just watched a programme about Jocelyn Bell Burnell who discovered Pulsars in the 60's .. very interesting indeed.

One of her last comments were about scientists of the present/future and questions they will be finding the answers to .. Such as why is space accelerating faster than at any time in the past?

Like i said .. Knowing very little on the subject, i have just grabbed a pen, done some freaky little diagrams, and made notes .. So if you know the answers to any of these questions then i would be grateful for your insight in this matter ..

Could the universe a particular shape that could explain the acceleration?
Is it a shape at all?

As energy is being used, you'd expect to an extent, de-acceleration over a period of time .. That would be the simplest of answers .. This is wrong or inaccuate to them .. But if something is churning up all this energy (both my index fingers are going in a circular motion there) couldn't the motion build up to actually increase acceleration?

Or could possibly as the big bang happened at a particular point and has been extending outwards since .. Could not maybe the space it's now entertaining be filled with something different (maybe denser) than what it has in the past?

And lastly .. the big bang happened 14 - 15 billion years ago .. If we have gained the knowledge to witness the beginning of time (big bang) then why can't we go past that to see just where the universe actually ends???
That is very black and white, i know.

A stupid question is only one that is never asked ..

Thank you.

 

[BlueScreen]

I've done subjects on it, but I'm not sure if they know why it is expanding, just that it is (or they propose that it is because it is a simple explanation which agrees with observations).

By expanding they actually mean space is expanding like a balloon. So a metre in space stretches to be more than a metre some time later. It's a little freaky. Some objects a long, long way away appear to move away from eachother faster than the speed of light because of it also. I don't know, but this might limit how far back we can see with telescopes too.

I'm about to go to work, but looked on wikipedia for you and this is a start on it. The general relativity stuff about metrics might be confusing, but the history and explanations are an easier read.

 

[Alpha Prime]

I believe, they believe, it is related to the great degree of dark matter that is present in the Universe.

 

[Willfrey]

It's often considered one of the greatest mysteries. There is no real 'this is why' theory that is widley accepted.

I'd suggest picking up a book called 'An Elegant Universe'

The beginning of the book deals a lot with relativity, time dialation, the properties and theories of the universe on a grand scale, etc.

 

[JocktheMotie]

I think, and this is a tentative think, that Dark Energy is used primarily to explain this phenomena. Dark Energy has a constant energy density and permeates the fabric of spacetime, it apparently accelerates the expansion of the universe due to it having negative pressure.

 

[Mole]

The universe will disappear

What is extraordinary is that the universe is accelerating away from us at such a rate that eventually the whole universe, except our Milky Way held together by gravity, will pass beyond our event horizon and so become invisible.

So in the future there will be no evidence the Big Bang ever existed.

So it is only in this special time of the universe that we can know where we came from and where we are going.

 

[sLiPpY]

Eventually, dark matter will overtake matter. The entire mass of the universe will compress into a very small space and become unstable.

Then *big bang!* a whole new universe is born! Ripping like a wave down a string, and the song continues.

 

[EcK]

Space isn't accelerating, its expansion is as far as we know. Accelerating space assumes that space can be compared to another frame of reference as in 'relative to x'

 

[sLiPpY]

Space isn't accelerating, its expansion is as far as we know. Accelerating space assumes that space can be compared to another frame of reference as in 'relative to x'

SPACE.com -- Deformed Galaxies Confirm Universe's Acceleration

Relative to deformed galaxies? Not sure if we're all using the term "acceleration" in the same context? But it's been a widely accepted topic in Astronomy for many...many years and a phenomena originally observed and speculated on by Hubble before any of us were born.

 

[Mole]

Eventually, dark matter will overtake matter. The entire mass of the universe will compress into a very small space and become unstable.

Then *big bang!* a whole new universe is born! Ripping like a wave down a string, and the song continues.

We now know this is entirely wrong and the universe is not only expanding but the expansion is accelerating and the acceleration will not slow or reverse.

And interestingly it was couple of Australian astronomers just down the road from me at the Stromlo Observatory, in Canberra, Australia, who made this discovery only recently.

 

[JocktheMotie]

SPACE.com -- Deformed Galaxies Confirm Universe's Acceleration

Relative to deformed galaxies? Not sure if we're all using the term "acceleration" in the same context? But it's been a widely accepted topic in Astronomy for many...many years and a phenomena originally observed and speculated on by Hubble before any of us were born.

He means that "space" as an entity, is not accelerating because there's nothing its motion is able to be compared against. Its expansion is. He was mostly referring to the accuracy of the thread title, I assume.

 

[sLiPpY]

We now know this is entirely wrong and the universe is not only expanding but the expansion is accelerating and the acceleration will not slow or reverse.

And interestingly it was couple of Australian astronomers just down the road from me at the Stromlo Observatory, in Canberra, Australia, who made this discovery only recently.

It'd be interesting to read a summary of their research. I'm not much of a detail person, I simply like to explore concepts.

Even as the universe expands, galaxies merge...just as surely as the Milkway and Andromeda will evenutally become deformed.

There's a lot yet to be understood about dark energy, and am quite fond of the Big Crunch theory...

Simply because the outcome would be similar to flushing a giant toilet bowl.

 

[Mole]

It'd be interesting to read a summary of their research. I'm not much of a detail person, I simply like to explore concepts.

Even as the universe expands, galaxies merge...just as surely as the Milkway and Andromeda will evenutally become deformed.

Sure it is contest between gravity and the expansion of space. And the Milky Way and Andromeda will merge but remember, the expansion of space is accelerating and gravity is not accelerating, so eventually the expansion of space will take all matter not bound to us gravitationally out of sight over our event horizon. And then we will be completely, forever alone.

And remember our event horizon is only 13.7 billion light years away.

Early explorers feared that if they sailed too far they would tip over the edge of the world. Well, the event horizon is the edge of our world.

 

[JocktheMotie]

It'd be interesting to read a summary of their research. I'm not much of a detail person, I simply like to explore concepts.

Even as the universe expands, galaxies merge...just as surely as the Milkway and Andromeda will evenutally become deformed.

Every galaxy, generally, is moving faster and faster away from each other. There are some local deviations, but they are in the vast minority. Dark Matter is already more abundant than regular matter. And yet, the universe is expanding. The "big crunch" is unlikely.

 

[sLiPpY]

Every galaxy, generally, is moving faster and faster away from each other. There are some local deviations, but they are in the vast minority. Dark Matter is already more abundant than regular matter. And yet, the universe is expanding. The "big crunch" is unlikely.

'big crunch' seems the most likely candidate to get back to a singularity?

***just for fun

The term "big bang" started as a joke -- a derogatory remark made by astronomer Fred Hoyle. But the name stuck and spawned a series of nomenclature knockoffs. A universe that expands forever will yield a "big chill" or a "big freeze." A universe that collapses into a singularity and explodes outward again will experience a "big crunch" followed by a "big bounce." And a universe that reaches equilibrium and does nothing will become a "big bore."

 

[JocktheMotie]

'big crunch' seems the most likely candidate to get back to a singularity?

Well sure. But the universe isn't headed back to a singularity. I don't know why think it is.

 

[Snoopy22]

Wild guess, the further things become removed gravitational forces become less (just off the top of my head so no science involved).

 

[EcK]

Relative to deformed galaxies?

That doesn't even mean anything

Not sure if we're all using the term "acceleration" in the same context?

enlighten me, the dictionary guys'll want to hear that bit.

But it's been a widely accepted topic in Astronomy for many...many years and a phenomena originally observed and speculated on by Hubble before any of us were born.

I meant, its expansion is accelerating, not 'space', but the expansion of space.
And thank you, I know all that already

before any of us were born.

Assumptions assumptions, young man

 

[sLiPpY]

Well sure. But the universe isn't headed back to a singularity. I don't know why think it is.

A hydrogen cloud sometimes collapses to become a star. There must be sufficient pressure, density, and heat obtained to initiate fusion of hydrogen nuclei to form helium nuclei. The energy formed in process of fusion is essentially a consequence of gravitational collapse.

The gravatational collapse is a reversion from the high energy potential resulting from the big bang, essentially to a lower energy potential as matter returns locally to singularity.

A. All energy formed in process of fusion is a consequence of gravitational collapse.
B. Gravitational collapse is a reversion from the high energy potential resulting from the big bang as matter attempts to return locally to singularity.
C. Will there be a gravitational repayment on the huge investment in outward momentum at the big bang?

It's fun to think about, like pulling on a rubber band.

 

[sLiPpY]

Assumptions assumptions, young man