Universe expansion

[justinater22]

It is pretty clear that the universe is expanding because of the galaxies moving away from one another. But how does that work? I read that is what dark matter or dark energy does. I'm curious how dark energy could use gravity as a repulsive force, or is there another idea of how this might be happening?

[Airbrush]

It is pretty clear that the universe is expanding because of the galaxies moving away from one another. But how does that work? I read that is what dark matter or dark energy does. I'm curious how dark energy could use gravity as a repulsive force, or is there another idea of how this might be happening?

 

Expansion is from the Big Bang, the acceleration of expansion is currently explained by dark energy. Dark matter has nothing to do with it, nor does gravity. Gravity and dark matter work against expansion. Dark energy does not "use" gravity.

[justinater22]

 

Expansion is from the Big Bang, the acceleration of expansion is currently explained by dark energy. Dark matter has nothing to do with it, nor does gravity. Gravity and dark matter work against expansion. Dark energy does not "use" gravity.

Yea I figured it wasn't both I just didn't know which one. And is it known yet how the dark energy makes the universe expand?

Edited December 5, 2012 by justinater22

[justinater22]

 

They don't know and openly admit that. But dark energy does not make the universe expand, it only accelerates the expansion from the Big Bang.

 

 

That's what I want to know how does it theoretically make the universe expand?

[ACG52]

That's what I want to know how does it theoretically make the universe expand?

 

One idea is that dark energy is a negative energy, which creates a negative pressure. A negative pressure is expansive, just as a positive pressure is compressive.

[imatfaal]

This "Dark Energy" (DE) is very interesting. It apparently has the negative force, to make huge objects, like galaxies, fly apart from each other in grand and spectacular fashion - completely defying Gravity!

 

This would be highly useful on Earth. Even if used on a smaller scale. For example, in the aircraft industry, or in building. The engineering and architectural advantages are clear. And for sport and leisure.

 

Will scientific research enable us to control and exploit this "DE"? Or should we re-investigate the possibilities of negative-weight Phlogiston.

 

Phlogiston in the 18th Century. Dark Energy in the 21st. Both equally absurd. Nothing really changes, does it?

 

 

I think many scientists are waiting for the next Lavoisier who will clarify and simplify matters. Phlogiston, whilst obsolete now, was an important step; scientists knew stuff was going on that they couldn't explain (burning, giving off heat and changing substances) they hypothesised, tested, fudged, accepted for a while (about 100 years), moved on with better experimental technique help to guide the way to better theory. We are at the stage of realising that the universe is accelerating in its expansion and we don't know why - paralleled by the 17th century chemists understanding a chemical reaction was happening between substances when combustion occurred. We might well still be missing equivalent of the vital experimental data (ie that gases had mass) that allowed Lavoisier to move chemistry on to a new level, we might be just theoretically too inept, or we may be getting close; it's certainly still an open book.

[dripto biswas]

dark energy is what theoretically reacts against the force of gravity at just the correct rate to prevent recollapse. just imagine a yourself blowing up a balloon. the more you blow, the more it expands.

the tension in the rubber membrane of the balloon causes the balloon to return to its original shape. but the air you blow from inside is what keeps the balloon expanding. our universe is like this balloon, gravity like the the tension in its membrane and the blowing force is like the dark energy. just like your blow will eventually come to an end, there will be a time when gravity will take over from dark energy causing it to recollapse.

[juanrga]

It is pretty clear that the universe is expanding because of the galaxies moving away from one another. But how does that work? I read that is what dark matter or dark energy does. I'm curious how dark energy could use gravity as a repulsive force, or is there another idea of how this might be happening?

 

The expansion of the universe is unrelated to dark energy or dark matter and cannot be explained as a repulsive force, because in general relativity neither gravitation nor space expansions are described by any force.

 

The origin of the expansion is on the Big Bang, but there is not universally accepted theory about what happened at the first instant of time. Our confirmed theories cease to work much before.

[Klaynos]

!

Moderator Note

Some of topic speculative posts have been split off to here:

http://www.scienceforums.net/topic/71452-modern-cosmology-is-wrong/

[Klaynos]

!

Moderator Note

More off topic hijacking removed, sorry I didn't quite realise how bignoring the issue was.

http://www.scienceforums.net/topic/71493-jdizz-on-the-univese/

Please no one else hijack this thread, well done on trudging through term crap justinater22

[alpha2cen]

 

The expansion of the universe is unrelated to dark energy or dark matter and cannot be explained as a repulsive force, because in general relativity neither gravitation nor space expansions are described by any force.

 

The origin of the expansion is on the Big Bang, but there is not universally accepted theory about what happened at the first instant of time. Our confirmed theories cease to work much before.

Space volume expansion, or intergalactic distance increment ?

[juanrga]

Space volume expansion, or intergalactic distance increment ?

Space volume expansion in non-bounded regions: this includes intergalactic regions.

[alpha2cen]

Space volume expansion in non-bounded regions: this includes intergalactic regions.

The details are like this.

http://www.scienceforums.net/topic/70266-redshift/#entry717865

Think it again.

Which one is correct among them?

[Spyman]

In physical cosmology, the term peculiar velocity (or peculiar motion) refers to the components of a receding galaxy's velocity that cannot be explained by Hubble's law.

According to Hubble, and as verified by many astronomers, a galaxy is receding from us at a speed proportional to its distance. The relationship between speed and distance would be exact in the absence of other effects.

Galaxies are not distributed evenly throughout observable space, but typically found in groups or clusters, ranging in size from fewer than a dozen to several thousands. All these nearby galaxies have a gravitational effect, to the extent that the original galaxy can have a velocity of over 1,000 km/s in an apparently random direction. This velocity will therefore add, or subtract, from the radial velocity that one would expect from Hubble's law.

The main consequence is that, in determining the distance of a single galaxy, a possible error must be assumed. This error becomes smaller, relative to the total speed, as the distance increases.

A more accurate estimate can be made by taking the average velocity of a group of galaxies: the peculiar velocities, assumed to be essentially random, will cancel each other, leaving a much more accurate measurement.
http://en.wikipedia.org/wiki/Peculiar_velocity#Cosmology

[alpha2cen]

Near Inflation, the receding speed of the faraway galaxy is not so high.

0-------------->speed increasing

So, if we see the faraway super cluster, we can see slow moving dim supercluster.

Is it really? Or, it is a nonsense?

http://blogs.scienceforums.net/alpha2cen/files/2011/02/core-calcu.jpg

http://blogs.scienceforums.net/alpha2cen/files/2011/02/Core_universe.jpg

Edited December 11, 2012 by alpha2cen

[Spyman]

Near Inflation, the receding speed of the faraway galaxy is not so high.

Wrong, shortly after the Big Bang event the expansion was extremely high and far away objects was receding with many multiples of the speed of light.

 

In physical cosmology the inflationary epoch was the period in the evolution of the early universe when, according to inflation theory, the universe underwent an extremely rapid exponential expansion. This rapid expansion increased the linear dimensions of the early universe by a factor of at least 10²⁶ (and possibly a much larger factor), and so increased its volume by a factor of at least 10⁷⁸.

http://en.wikipedia.org/wiki/Inflationary_epoch

 

The Big Bang theory is the prevailing cosmological model that describes the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the Universe to cool and resulted in its present continuously expanding state.

http://en.wikipedia.org/wiki/Big_Bang

Edited December 11, 2012 by Spyman

[alpha2cen]

I have found a reference material about early Universe star. But there is no coment about red shift.

http://phys.org/news/2012-12-stars-universe-million-years.html

How do they calculate the age of early Universe ?

Edited December 11, 2012 by alpha2cen

[WorriedLad]

The moderator Klaynos stated in post $ 9

Some of topic speculative posts have been split off to here:

http://www.sciencefo...ology-is-wrong/

which action is definitely recommendable to separate serious science from personal fringe beliefs,

However, the moderator has also moved to the "speculative" post Santilli's diagram establishing that the cosmological redshifts measured on Earth cannot be the same for other observers in the universe, thus confirming the view by Hubble, de Broglie, Fermi et al that the ACCELERATION of the believed expansion necessarily implies Earth at the center of the universe because of its evident radial character in all directions from Earth.

Additionally, the moderator has eliminated references to the independent experimental verifications of Santilli's IsoRedShift and other experimental data perhaps because disproving widely accepted beliefs.

Quite respectfully, I believe these actions have damaged this blog because they have turned this site into this incredible chain of extremely farfetched personal speculations, while the website http://www.sciencefo...ology-is-wrong/ is the scientific one with rigorous verification of statements and at least experimental verifications on Earth.

[Klaynos]

The moderator Klaynos stated in post $ 9

 

Some of topic speculative posts have been split off to here:

 

http://www.sciencefo...ology-is-wrong/

 

which action is definitely recommendable to separate serious science from personal fringe beliefs,

 

However, the moderator has also moved to the "speculative" post Santilli's diagram establishing that the cosmological redshifts measured on Earth cannot be the same for other observers in the universe, thus confirming the view by Hubble, de Broglie, Fermi et al that the ACCELERATION of the believed expansion necessarily implies Earth at the center of the universe because of its evident radial character in all directions from Earth.

 

Additionally, the moderator has eliminated references to the independent experimental verifications of Santilli's IsoRedShift and other experimental data perhaps because disproving widely accepted beliefs.

 

Quite respectfully, I believe these actions have damaged this blog because they have turned this site into this incredible chain of extremely farfetched personal speculations, while the website http://www.sciencefo...ology-is-wrong/ is the scientific one with rigorous verification of statements and at least experimental verifications on Earth.

 

 

 

 

!

Moderator Note

Please do not derail threads by replying to moderator action, either send a pm to a staff member or use the report post feature.

 

I also don't believe ay posts have been deleted.

[Widdekind]

i understand, that the fabric of space-time, as a (3+1)D membrane, is not expanding, in a "hyper-dimensional" sense, viewing the membrane from the higher-dimensional "bulk" in which it resides. For example, imagine a (1+1)D space-time (x,t), visualized as a single sheet of paper, trimmed into a triangle, with the tip "down" towards the viewer. Time runs vertically, space horizontally. As time increases, from bottom tip to top edge, the space extent of that fabric increases. So, 1D space seems to expand. But the whole sheet of (trimmed) paper simply sits there on the desk -- (1+1)D space-time is static, unchanging, non-expanding.

[alpha2cen]

Wrong, shortly after the Big Bang event the expansion was extremely high and far away objects was receding with many multiples of the speed of light.

 

In physical cosmology the inflationary epoch was the period in the evolution of the early universe when, according to inflation theory, the universe underwent an extremely rapid exponential expansion. This rapid expansion increased the linear dimensions of the early universe by a factor of at least 10²⁶ (and possibly a much larger factor), and so increased its volume by a factor of at least 10⁷⁸.

http://en.wikipedia.org/wiki/Inflationary_epoch

 

The Big Bang theory is the prevailing cosmological model that describes the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the Universe to cool and resulted in its present continuously expanding state.

http://en.wikipedia.org/wiki/Big_Bang

Red shift value did not appear in the past post.

Without any acceleration, the expansion or contraction speed can not approach to the certain value.

Always initial velocity is zero.

[Spyman]

Red shift value did not appear in the past post.

Without any acceleration, the expansion or contraction speed can not approach to the certain value.

Always initial velocity is zero.

But we don't know the initial conditions at time zero in the Big Bang.

 

We can only observe and measure conditions shortly after the Big Bang and when the Cosmic Microwave Background Radiation we see today was emitted ~14 billion years ago, space between the emitter and us was already expanding with more than 56 times lightspeed.

(The CMBR has a redshift of z=1089.)

Edited December 13, 2012 by Spyman

[alpha2cen]

How do we calculate the age of dim star? Are there no scenario from the beginning to the present?

[Spyman]

If we know the distance then the constancy of lightspeed tells us how long time light has travelled to reach us.

 

There was no stars at time zero and before the Recombination epoch space was not transparent for light.
(Recombination occurred around 377 000 years after the Big Bang.)

[michel123456]

i understand, that the fabric of space-time, as a (3+1)D membrane, is not expanding, in a "hyper-dimensional" sense, viewing the membrane from the higher-dimensional "bulk" in which it resides. For example, imagine a (1+1)D space-time (x,t), visualized as a single sheet of paper, trimmed into a triangle, with the tip "down" towards the viewer. Time runs vertically, space horizontally. As time increases, from bottom tip to top edge, the space extent of that fabric increases. So, 1D space seems to expand. But the whole sheet of (trimmed) paper simply sits there on the desk -- (1+1)D space-time is static, unchanging, non-expanding.

 

IIRC that is the standard POV. The metric of space is expanding.

Edited December 13, 2012 by michel123456