Dark Matter (Anti-Matter)

[RedShift1121]

Dark matter, science's new threat to the universe. But what is it? Some people call it the anti-gravity. If this is true this means the universe should, theoretically, be shrinking instead of expanding. what do you think?

[Zarnaxus]

If it is anti-gravity, then it should push~expand. Gravity pulls.

 

Dark matter is definitely one of the most peculiar problems with theoretical physics right now.

 

The solution: possibly SUSY (supersymmetry)

 

Supersymmetry states that for every particle, there is a supersymmetric partner particle which differs by half a unit of spin. Each boson has a fermionic superpartner, and each fermion has a bosonic superpartner. These superpartners are estimated to be much larger and weakly interacting that regular matter. They have most likely decayed into their most stable form, the neutralino. If this is true (there is no proof currently), then dark matter is probably just neutralinos, which we are hoping to detect at the LHC in geneva, switzerland. Also, they have probably accumulated at the centers of high-gravity masses like galaxies and stars. They can shoot off neutrinos, which scientists are trying to detect at IceCube in the south pole (it just recently got finished).

 

 

 

Oh! and dark matter and antimatter are completely different things. Antimatter has been created in the lab. Dark matter has not and is more unknown.

[RedShift1121]

Hmm, interesting. It has been here from the beginning of the universe and I guess it is here to stay. Not too sure whether we can pick up on it but it is definitely there. Einstein noticed it and I think there should be more research going into Dark Matter as it is a vague area of Astrophysics. But when you put it like that I suppose it's one step closer to finding out why or where it came from. Thanks! ;D

[Airbrush]

Dark matter may occupy dimensions we cannot explore. "There" it exists and has a ghost gravity, but because it exists in higher dimensions, we cannot detect it, only it's effect.

[Zarnaxus]

Dark matter may occupy dimensions we cannot explore. "There" it exists and has a ghost gravity, but because it exists in higher dimensions, we cannot detect it, only it's effect.

 

 

Could you define: "it's effect?"

[RedShift1121]

Yeah, please. would like to know more about it's effect on the universe and it's potential dangers.

[Airbrush]

Could you define: "it's effect?"

 

It's effect is gravity. We cannot see it, which is not saying much for our ability to see things, we can only calculate it's mass by its' gravitational effect on galaxy rotation.

[Zarnaxus]

can we detect it with how much it bends light waves?

[Moontanman]

Yeah, please. would like to know more about it's effect on the universe and it's potential dangers.

 

 

Danger? Could you elaborate on that?

[Spyman]

When reading through this thread I notice there seems to be some confusion of what different phenomenas are called and what they signify.

 

 

Dark Matter

Dark matter is not considered a threat to the Universe, it have ordinary gravity and is not thought to consist of antimatter.

 

Dark matter is some yet unknown kind of matter that exists in large amounts inside our galaxy and other galaxies, it helps to keep them together against its rotation. It is called dark because we don't know what it is, it doesn't interact with light so we can't see it directly but we can observe its gravitational effect on stars in our surroundings. Like normal matter it has been around as long as the Universe

 

There is no scientific consensus on Dark matter occupying any higher dimensions or even that there exists any such dimensions, it is most likely thought to be some kind of exotic matter that exists just like normal matter in the ordinary dimensions with normal gravity.

 

We observe Dark matter by measuring how fast stars are orbiting at different distances from the galactic center. Since they seem to be rotating at higher velocities than what the visible matter we can see should be able to hold gravitationally, there must be something else pulling on them.

 

More reading here: http://en.wikipedia.org/wiki/Dark_matter

 

 

Antimatter

Antimatter is exactly like normal matter except that it consists of particles with opposite electrical charge and as such can we see it and it has normal gravity. As have been said it has been created artificially in small quantities. The danger with antimatter is that it reacts strongly if it comes in contact with normal matter and annihilates both itself and the matter it comes in contact with, so it has to be kept in electromagnetic containers.

 

Theoretically there is a large problem with antimatter since the Universe should contain an equal amount of anti as normal matter but we can't observe any large quantities of antimatter. If large quantities would be found they could pose a threat if moving in our direction since gravity could pull us together to a hypothetical super annihilation.

 

More reading here: http://en.wikipedia.org/wiki/Antimatter

 

 

Dark Energy

Dark energy is the name for the strange force pushing the Universe apart at an ever increasing rate. Like Dark matter it is called Dark because we don't yet know what it is, we can only observe its affect on very distant objects in the Universe.

 

When we observe the redshift of distant stars we can measure how fast they are moving away from us, like a cosmological doppler meter and when we look a objects very far away we are also looking back in time since it takes time for the light from them to reach us. By measuring how fast objects at different distances are moving away from us and comparing to how fast they should be receding according to the Hubble constant we have discovered that for the first ~5 billion years after the Big Bang, gravity had the upper hand and was slowly slowing down the rate of expansion, but by then the forces of gravity had been reduced due to the huge distances involved and when it got to weak compared to Dark energy the rate of expansion started to speed up again.

 

Dark energy could be considered a threat to the Universe since it seems to be strong enough to cause an definite end, where the Universe slowly dies dark and cold without any reasonable possibility to recycle into a new Big Bang and it might turn out to be exponential which would cause everything down to atoms in the Universe to be ripped apart.

 

More reading here: http://en.wikipedia.org/wiki/Dark_energy

Edited May 4, 2011 by Spyman

[imatfaal]

Nice simple but explanatory post Spyman - I think something along these lines might be a good idea to make as a sticky; there is so much confusion (caused in part by the naming) in the realms of dark matter / dark energy and anti-matter and loads of posts are premised on simple misunderstandings

[A Tripolation]

Nice simple but explanatory post Spyman - I think something along these lines might be a good idea to make as a sticky; there is so much confusion (caused in part by the naming) in the realms of dark matter / dark energy and anti-matter and loads of posts are premised on simple misunderstandings

 

I second this. An extraordinary post for us simpletons to read.

[Airbrush]

can we detect it with how much it bends light waves?

 

Good question. Anyone know if the magnitude of gravitational lensing tells us exactly how much matter (dark and ordinary) is causing the bending? I think they only roughly estimate there is about 4 times as much dark matter as ordinary matter. How precise is this estimate?

[Zarnaxus]

God's Cook Book

Recipe One: The Universe

Ingredients

1. ~73% Dark Energy
2. ~23% Dark Matter
3. ~3% Free Hydrogen and Helium
4. ~0.5% Stars
5. ~0.3% Neutrinos
6. ~0.2% Space Junk

Directions: Mix together in three spatial dimensions. Wait 13.74 billion years. Brag to Odin. Watch him take the credit. Cry about it.

 

 

[Spyman]

Good question. Anyone know if the magnitude of gravitational lensing tells us exactly how much matter (dark and ordinary) is causing the bending? I think they only roughly estimate there is about 4 times as much dark matter as ordinary matter. How precise is this estimate?

Baryon density 0.0456 ± 0.0016, Dark matter density 0.227 ± 0.014, Dark energy density 0.728 +0.015 −0.016

 

Page 39 has values with toleranses: http://lambda.gsfc.nasa.gov/product/map/dr4/pub_papers/sevenyear/basic_results/wmap_7yr_basic_results.pdf

Edited May 5, 2011 by Spyman

[Airbrush]

Baryon density 0.0456 ± 0.0016, Dark matter density 0.227 ± 0.014, Dark energy density 0.728 +0.015 −0.016

 

Thanks for the info Spyman. Could you please help us convert these values into everyday English? About how much more dark matter is there than ordinary matter? Is there more or less than 4 times as much dark matter as ordinary matter? Exactly how much more dark than ordinary matter as precisely as you can tell? Do these values come from measuring galactic rotation or lensing?

[IM Egdall]

Spyman and Zarnaxus already gave us the answer. If you add up the densities given by Spyman, they add up to 1. To summarize, the visible universe as we currently understand it is made up of:

 

Ordinary matter - about 4%. Per Zarnaxus, it includes: 3% Free Hydrogen and Helium, ~0.5% Stars, ~0.3% Neutrinos, ~0.2% Space Junk

 

Dark Matter - about 23%

 

Dark Energy - about 73%

 

Now the density figures that Spyman gave us refer to the percentage critical density. The critical density is the overall mass/energy density value of the universe which gives an overall zero spacetime curvature, aka a "flat" universe. In metric units, this critical density is about 10^^-23 grams per cubic meter.

 

The currently most accepted explanation for why our visible universe happens to have just the right overall density value for a flat universe is Inflation theory. See link:

 

http://en.wikipedia....tion_(cosmology)

Edited May 5, 2011 by I ME

[Spyman]

Thanks for the info Spyman. Could you please help us convert these values into everyday English? About how much more dark matter is there than ordinary matter? Is there more or less than 4 times as much dark matter as ordinary matter? Exactly how much more dark than ordinary matter as precisely as you can tell? Do these values come from measuring galactic rotation or lensing?

As I ME says, all you have to do is multipying with one hundred to get the values in overall precentage like this:

 

Ordinary matter 100 × (0.0456 ± 0.0016) = 4.56% ± 0.16% and Dark matter 100 × (0.227 ± 0.014) = 22.7% ± 1.4%

 

 

And their relation to each other is:

 

Maximum = (22.7+1.4) / (4.56-0.16) = 5.48 times and Minimum = (22.7-1.4) / (4.56+0.16) = 4.51 times.

 

So as I interpret those numbers there is ~5 times more Dark matter than ordinary matter.

 

 

I don't know how the values are extracted or combined from different observations but WMAP measures the CMBR.

 

The Wilkinson Microwave Anisotropy Probe (WMAP) - also known as the Microwave Anisotropy Probe (MAP), and Explorer 80 - is a spacecraft which measures differences in the temperature of the Big Bang's remnant radiant heat - the Cosmic Microwave Background Radiation - across the full sky.

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

 

In cosmology, cosmic microwave background (CMB) radiation (also CMBR, CBR, MBR, and relic radiation) is thermal radiation filling the universe almost uniformly.

...

When the universe was young, before the formation of stars and planets, it was smaller, much hotter, and filled with a uniform glow from its white-hot fog of hydrogen plasma. As the universe expanded, both the plasma and the radiation filling it grew cooler. When the universe cooled enough, stable atoms could form. These atoms could no longer absorb the thermal radiation, and the universe became transparent instead of being an opaque fog. The photons that existed at that time have been propagating ever since, though growing fainter and less energetic, since exactly the same photons fill a larger and larger universe.

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

Edited May 6, 2011 by Spyman

[Airbrush]

That's a fairly precise estimate, 4.51 to 5.48 times as much dark matter as ordinary matter. Wikipedia is off by 20%. Maybe someone should edit Wikipedia with this data.

 

"According to observations of structures larger than galaxies, as well as Big Bang cosmology interpreted under the Friedmann equations and the FLRW metric, dark matter accounts for 23% of the mass-energy density of the observable universe. In comparison, ordinary matter accounts for only 4.6% of the mass-energy density of the observable universe, with the remainder being attributable to dark energy. From these figures, dark matter constitutes 80% of the matter in the universe, while ordinary matter makes up only 20%.

 

80% is 4 times 20%, so Wiki is off by 20%.

 

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

Edited May 6, 2011 by Airbrush

[Airbrush]

WIKIPEDIA ERROR:

 

"According to observations of structures larger than galaxies, as well as Big Bang cosmology interpreted under the Friedmann equations and the FLRW metric, dark matter accounts for 23% of the mass-energy density of the observable universe. In comparison, ordinary matter accounts for only 4.6% of the mass-energy density of the observable universe, with the remainder being attributable to dark energy. From these figures, dark matter constitutes 80% of the matter in the universe, while ordinary matter makes up only 20%".

 

80% is 4 times 20%, so Wiki is off. It should say "...dark matter constitutes 83.3% of the matter in the universe, while ordinary matter makes up only 16.7%."

 

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

Edited May 7, 2011 by Airbrush

[Spyman]

Maybe someone should edit Wikipedia with this data.

It should say "...dark matter constitutes 83.3% of the matter in the universe, while ordinary matter makes up only 16.7%."

Seems like someone heard you...

 

From these figures, dark matter constitutes 83% of the matter in the universe, while ordinary matter makes up only 17%.

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

[Airbrush]

I went ahead and made the edits myself, hahaha. Thanks for everything.

[gabl8a89]

If the dark matter occupy the higher dimension,

will I ends up collapsing with a virtual black hole in the computer lab

and being rip apart?

[Spyman]

If the dark matter occupy the higher dimension,

will I ends up collapsing with a virtual black hole in the computer lab

and being rip apart?

If you continue to use whatever you seem to be taking, I think you will end up in a severe nightmare...

[Widdekind]

Water freezes, into a huge inter-stellar reservoir, of comets ("inter-stellar blizzard hail-storm") ??

 

In regions of space where the temperature is only 30 degrees above absolute zero, water was found to be far less plentiful than expected. Conversely... "within gas clouds where new stars are being born, the gas can be heated to temperatures of several thousand degrees Fahrenheit; here the water concentration seems to be as much as 10 thousand times larger."

 

...the amount of Oxygen is much lower than expected... "most of the oxygen atoms in interstellar space remain hidden in some form that we have yet to detect."

 

...

 

water abundance in the interstellar medium is very variable. Observations of several giant molecular clouds indicate that the water abundance in these objects is more than an order of magnitude lower than the predictions of models of the interstellar medium. The water abundance in 'translucent clouds', observed in absorption toward Sgr B2, is approximately as predicted, as is the water abundance in regions that have been compressed by shock waves associated with proto-stellar outflows... SWAS has not yet detected molecular oxygen in the interstellar medium, indicating that the abundance of molecular oxygen is at least a factor of 10 to 100 lower than predicted by steady-state models.

 

http://www.spaceref.com/news/viewnews.html?id=204

 

Nearly 1% of our sun's mass is Oxygen, roughly equivalent to the mass of Jupiter. What if the Oxygen forms water, and the water freezes, into an "inter-stellar blizzard hail-storm", of cold comets ? Perhaps the water is chemically incorporated, into dust grains, as some sort of "low-temperature-only" hydrate, which off-gases & releases the water, for T > 30 K ?

 

in the very coldest reaches, where temperatures are found just 30 degrees above absolute zero, astronomers measured water vapor concentrations of only a few parts per billion... In warmer regions of space, though, water vapor is more plentiful.

 

http://www.spaceref.com/news/viewpr.html?pid=2431

Edited May 18, 2011 by Widdekind