I'm quite a novice when it comes to astronomy but can I ask one question?

Question

I've been doing some reading lately and am very interested in dark matter. Can someone give me a very brief explanation of what exactly dark matter is believed to be and who are some of the scientists who have introduced us to our, albeit limited, understanding of the subject.

Answer 1

To be honest, "dark matter" is a term describing matter which, to the scientific community, is obscure. It's an explanation of a sort to help explain calculations which indicate to astronomers and physicists that more matter "than meets the eye" is out there.

I can't direct you to much on the subject, because there's much more speculation than hard fact available right now. Maybe in another decade or two.

Answer 2

As others have highlighted, dark matter and energy is material that is simply unaccounted for, and may be a different form of matter than "normal" (baryonic) matter. I feel this may be correct because if you think of the composition of our own solar system, 99% of the mass is composed of the Sun. All the planets, asteroids, Kuiper Belt objects, and Oort cloud only make up 1% of the total mass in our solar system. Taking this information makes it seem plausible that the missing mass is more than just dust and planets. Although after reading more about dark dwarfs I may be wrong. However, it is not far fetched to think that dark matter may be a different variation of matter, present since the big bang, which is more dense than normal matter, and behaves differently than baryonic matter. The next step is to find out whether this hypothesis is true (or false). This will only be proven by continued efforts in particle physics and astronomy. Also, dark matter has been found, but determining its properties will likely prove to be much more difficult. What's important about dark matter is that has only been mapped because of its affect on surrounding barynoic matter.

As the essay by Joe Silk points out Fritz Zwicky is the first to realize the mass of galaxies was also coming from unseen matter- hence dark matter. Hubble's constant was also an important insight that helped scientists in their discovery of dark matter.

I found the article on eclipse.net to be the best for a layman (such as myself). I'd start there for a better answer than what I have given here.

Answer 3

Dark matter (and it's cousin, dark energy) was "discovered" because of the motions of galaxies - they were spinning too fast for the amount of matter seen.

After confirming that there's more gravitational force coming from galactic centers than can be accounted for, they came up with the name, "Dark Matter", which refers to matter that can't be seen or detected.

After formulating what "dark matter" might be, the leading theory is the "WIMP." Weakly Interactive Massive Particles - particles with a lot of mass, but pass right through most atoms without any interaction whatsoever. (The theory says there are billions passing through you right now.)

So, there are 5 or 6 sights around the world, most are deep inside mines (There's one 3 or 4 miles deep in an old Iron mine in Minnesota), looking for these particles. Most have very cold gas (liquid helium, liquid nitrogen, liquid argon, etc), with detectors inside - and, if the proposed particle hits the nuclei of one of the gases just right - a 90 degree blow to a proton, a 36 1/5 degree hit to a neutron, etc - it *should* make the atom vibrate for a very short time - and that vibration is detectable. If they discover just the right kind of vibration, that would be proof that WIMPs and Dark Matter exists.

Answer 4

Dark matter is simply matter that we cannot see, because it does not give off any light.

Astronomers have noticed that the behavior of stars in galaxies imply that these galaxies have a certain mass based on their gravitational effects. However, when they count all of the visible stars and calculate their total mass, there is some missing mass. This missing mass is called "dark matter" because no one has seen it.

Some scientists think that this dark matter could be planets, clouds of dust, subatomic particles, or some type of exotic matter than no one has discovered yet.

Answer 5

Dark Matter was first hypothesized by Fritz Zwicky in the 1930s, to explain the apparently high mass of the Coma cluster. In the 1970s and 1980s, it was found that Dark Matter is likely present in most galaxies, to explain their rotation curves. Vera Rubin was one of the principals in that work. Nowdays, the existence of Dark Matter is central to the standard model of cosmology, and seems to be consistent with all observations. The irritating thing is that we still don't know what it actually is.

Answer 6

Dark matter could be remnants of the Primordial Atom (the singularity or massive BLACK HOLE).

One grain of singularity has MORE MASS than our entire solar system

Now, look at a grain of salt and imagine it has MORE gravity than the SUN, EARTH, JUPITER, SATURN, URANS and NEPTUNE combined

ONE little grain.

Now if that stuff is out there it is a major gravity well, capable of sucking in nearby matter and growing larger.

If the gravity of that stuff is so strong that PHOTONS of light can't be emitted or released then it is BLACKER THAN BLACK.

But that's only a theory.

If you were at the EDGE of the universe what you would see would be SO BLACK, but as the GAMMA RADIATION moves outward it slowly lights it up to 3.6 degrees Kelvin.

Our Sun is 5,600 degree Kelvin

This is called CONTRAST

BLACKEST BLACK at less than 3.6 degrees Kelvin (optimumly at 0 Kelivn) and WHITE WHITE at 5,600 degree kelvin.

So you have a contrast range of 5,600:1

Your LCD TV set is 500:1 on the average.

The universe is 10 times greater on the average.

Photo graphic film can only see 100:1 maximum. And only in a small SLICE that is more like 10:1

And that is only under optimal conditions.

TV can only see 100:7 on average. It, too, is only on a small slice like 5:1

This is why you can't see STARS when you photograph the EARTH, because the CONTRAST RANGE exceeds photographic limits for a given exposure.

It is impossible to see GAMMA RAYS with any telescope visually because 3.6 degrees Kelvin is too faint.

The only way you can measure it is with radio telescope.

The SUN is 5,600 degree and GAMMA RAYS at the edge of the universe are 3.6 degrees


Dark matter is < than 3.6 degree

So, you look at a galaxy with a radio telescope and something between the EDGE and YOU is darker than 3.6 degrees and we call taht DARK MATTER.

If the GALAXY moves away, you would see beyond it to the EDGE of the UNIVERSE at 3.6 degrees

BUT it is CLOSER than the edge of the UNIVERSE and LESS than 3.6 degrees

So you give it property name.

DARK MATTER

SOMETHING darker than the EDGE of the UNIVERSE that is CLOSER than the EDGE of the UNIVERSE that OCCULTS the EDGE OF THE UNIVERSE.

We assume it has the SAME mass as light and thus nuetralizes light emissions.

When you look at your TV set, BLACK is actually 7 on the contrast scale.

The scale is 100 (white) to 7 (black)

Now imagine something LESS than 7 blocking your view.

Imagine something with SO much gravity it MAKES a dot on your set, BLACKER THAN BLACK

LESS than 7