dark matter and dark energy

[36grit]

Do you think dark matter and/or dark energy are expanding like the universe, or is their size more of a definite nature like the atom?

[imatfaal]

From my reading I think the general view of Dark Matter is that it is particulate - ie it is bits of as yet unknown stuff that will remain same size against a background of expanding space. I think, dark matter will - like ordinary matter - become more rare in an increasing space. In the future an average cubic lightyear of space will have less matter and less dark matter than an average cubic lyr today.

 

Dark Energy is really just a name given to a phenomenom we don't fully understand - but it is not thought to be particulate, it is more a conceptual- force, field, energy etc; and of course it is, by definition, the reason for the expansion. It does not dilute with expansion however - ie it maintains its ability to expand space and does not lose its effect. Conversely to matter, in the future a cubic lightyer of space will expand (ie same "quantity of dark energy") by the same amount as it does now

Edited July 14, 2011 by imatfaal

[Airbrush]

Dark energy is the repulsive property of empty space. The more empty space you have, the more repulsion. When the space is great enough the repulsion overcomes gravity, which only happens between superclusters of galaxies.

[pantheory]

Do you think dark matter and/or dark energy are expanding like the universe, or is their size more of a definite nature like the atom?

 

Consider that both dark matter and dark energy are mainstream hypothesis and other non-mainstream models might believe in one or the other, both or neither. According to the present mainstream ideas both dark matter and dark matter saturate the universe and therefore must also move with the expansion of space according to the mainstream model.

 

I personally believe neither dark matter or dark energy exists but details of such ideas belong in the speculation forum where I have an open thread. You could throw in a related question or more there, if you are interested in alternative models

 

regards

Edited July 14, 2011 by pantheory

[alpha2cen]

Recent issue is how to detect dark matter. We have tried to detect it by using telescope or underground instrument. There are many telescope photos about dark matter existence. But direct evidence of dark matter existence, i.e., underground instrument results are rare. Recent Italian scientist results seems to give us a clue of existence of dark matter.

[Airbrush]

Recent issue is how to detect dark matter. We have tried to detect it by using telescope or underground instrument. There are many telescope photos about dark matter existence. But direct evidence of dark matter existence, i.e., underground instrument results are rare. Recent Italian scientist results seems to give us a clue of existence of dark matter.

 

Please give us a link to these Italian scientists' results.

[BJC]

Please give us a link to these Italian scientists' results.

This is not the link to the Italian DAMA/LIBRA experiment but this link provides a possible verification of the result

The Dark Matter Data Bonanza

After years of skepticism over the existence of dark matter, a growing number of experiments are revealing that dark matter was there all along.

...

There is a way to separate the dark matter signal from all this background, however. As the Sun moves through the galaxy, it must also be moving through a sea of dark matter. And as the Earth moves around the Sun, it will plough more quickly into the sea of dark matter at some times of the year and at other times more slowly.

 

So the dark matter signal ought to have an annual modulation.

 

This is exactly what the DAMA/LIBRA people say they can see.

...

few weeks ago, a team with a detector called CoGeNT at the bottom of a mine in Minnesota announced that it had gathered very similar evidence to the DAMA/LIBRA experiment

 

 

Dark Energy

There is also the possibility that ordinary gravity repels antimatter. This could possible be tested at the CERN ALPHA experiment:

Antihydrogen Trapped For 1000 Seconds

The long term storage of significant amounts of antihydrogen should soon settle the question of whether antimatter falls up or down.

...

The news is significant because it makes possible a new set of experiments that should answer some important questions.

 

Most important of these is whether ordinary gravity attracts or repels antimatter. In other words, does antihydrogen fall up or down?

[alpha2cen]

Please give us a link to these Italian scientists' results.

 

This is the site.

http://www.guardian.co.uk/science/2008/apr/24/physics.sciencenews

Resent U.S. scientists also found the clue of the WIMP existence signal.

Have a look down side of the web page.

http://www.fnal.gov/pub/today/archive_2011/today11-06-08.html

[IM Egdall]

Question: if there is a sea of dark matter engulfing our solar system, why doesn't it coelesce due to its gravity into dark matter clumps and form dark matter planets, etc.?

[alpha2cen]

Question: if there is a sea of dark matter engulfing our solar system, why doesn't it coelesce due to its gravity into dark matter clumps and form dark matter planets, etc.?

 

We do not know how difficult it would be. Let us think about well known Rutherford experiment, he uses gold as a target material. Gold is condensed matter as you know, very many molecules are condensed in a small place. But he had a difficulty to find it, because one 8000ths is a space of the nucleus in the atom. Very small amount of particles are collided with nucleus. At the normal experiment 0.01% signal is treated as experiment error. Then, how about Dark Matter case. It has very wick interaction with matter and we do not know whether it has condensed state or not. And then we do not exactly know where it is in the space.

Edited July 21, 2011 by alpha2cen

[Airbrush]

Thanks for the links to the experiments to find dark matter and the WIMPs detected. Since WIMPs mean "weakly interacting" massive particles, maybe the weakly interacting characteristic makes them not clump together. Are WIMPs particles that are not atoms with nucleus and electrons?

 

So they may have found dark matter. They just need more confirmation which might take a while.

[36grit]

I think we'll soon learn that dark matter and dark energy are the result of accelerated gravitational expansion fueled by the constant increase in vacuum energy as part of the natural cycle of universes.

 

 

 

 

[imatfaal]

Question: if there is a sea of dark matter engulfing our solar system, why doesn't it coelesce due to its gravity into dark matter clumps and form dark matter planets, etc.?

 

It would need some form of self-interaction in order to disperse it's kinetic energy - otherwise it would never clump it would stay in motion. The fact that the presumed clouds of dark matter give off no heat/radiation makes it possible that it does not have this form mechanism to shed energy which normal matter does have.