wat is antimatter and dark matter?

Answer 1

Every elementary particle in the Universe appears to have a partner particle called its antiparticle that shares many of the same characteristics, but many other characteristics are the opposite of those for the particle. For example, the electron has as its antiparticle the antielectron. The electron and the antielectron have exactly the same masses, but they have exactly opposite electrical charges. The common stuff around us appears to be "matter", but we routinely produce antimatter in small quantities in high energy accelerator experiments. When a matter particle meets its antimatter particle they destroy each other completely (the technical term is "annihilation"), releasing the equivalent of their rest masses in the form of pure energy (according to the Einstein E=mc^2 relation). For example, when an electron meets an antielectron, the two annihilate and produce a burst of light having the energy corresponding to the masses of the two particles. Because the properties of matter and antimatter parallel each other, we believe that the physics and chemistry of a galaxy made entirely from antimatter would closely parallel that of our our matter galaxy. Thus, is is conceivable that life built on antimatter could have evolved at other places in the Universe, just as life based on matter has evolved here. (But if your antimatter twin should show up some day, I would advise against shaking hands---remember that matter and antimatter annihilate each other!) However, we have no evidence thus far for large concentrations of antimatter anywhere in the Universe. Everything that we see so far seems to be matter. If true, this is something of a mystery, because naively there are reasons from fundamental physics to believe that the Universe should have produced about as much matter as antimatter. Dark matter is the general term for matter that we cannot see to this point with our telescopes, but that we know must be there because we see its gravitational influence on the rest of the Universe. Many different experiments indicate that there is probably 10 times more matter in the Universe (because we see its gravitational influence) than the matter that we see. Thus, dark matter is basically what the Universe is made out of, but we don't yet know what it is! As one simple example of the evidence for dark matter, the velocity of rotation for spiral galaxies depends on the amount of mass contained in them. The outer parts of our own spiral galaxy, the Milky Way, are rotating much too fast to be consistent with the amount of matter that we can detect; in fact the data indicates that there must be about 10 times as much matter as we can see distributed in some diffuse halo of our galaxy to account for its rotation. The same is true for most other spiral galaxies where the velocities can be measured. There are various candidates for the dark matter, ranging from ordinary matter that we just can't see because it isn't bright enough (for example, ordinary matter bound up in black holes, or very faint stars, or large planet-like objects like Jupiter) to more exotic particles that have yet to be discovered. There are some fairly strong arguments based on the production of the light elements in the Big Bang indicating that the majority of the dark matter cannot be ordinary matter or antimatter (which physicists call "baryonic matter"), and thus that the majority of the mass of the Universe is in a form very different from the matter that makes up us and the world around us (physicists call this "non-baryonic matter"). If that is true, then the matter that we are made of (baryonic matter) is but a small impurity compared to the dominant matter in the universe (non-baryonic matter). As someone has put it, "not only are we not the center of the Universe, we aren't even made of the right stuff!"

Answer 2

Like many others have said antimatter is the "opposite" of matter. I say it with quotes because the term antimatter is misleading because technically, it's not anti-anything!

Because of the fact that matter and antimatter annihilates each other upon contact is the reason why it's called antimatter, but in reality it's just plain old normal-matter. What makes antimatter... ummm anti-, are certain quantum properties are different from its normal twin. In most cases, electric charge is opposite as in the case of the electron (-1) and the position (+1). But ALL OTHER PROPERTIES ARE THE SAME! So you see, it's not the exact opposite.

Antiparticles can have a whole slew of other properties reversed, quantum spin being the second most common. Also, nobody knows why matter and antimatter completely cancels into pure energy in the form of photons (light). There are also studies that seem to indicate that antimatter reacts differently to gravitational fields, in a way that Newtonian and Einsteinian theories can't explain. Interesting huh? Kinda implies that they're not exactly opposite.

Dark Matter is a whole other ball game. Some say it doesn't exist. Other say it's the superpartners of all known particles (Starndard Theory). Superpartners are particles related by supersymmetry. It states that every fermion (particles with a half-integer spin such as quarks, neutrinos, and antineutrinos) has an exact partner boson (particles with an integer spin such as photons). Boson are also force carriers, they're are what makes the 4 stand forces "work".

But nobody has detected an superpartners to date. Some scientists truly believe it's the "elusive" Higgs boson. This is the supposed boson that determines the mass of each and every particle of the Standard Theory. I personally believe the Higgs boson makes up for some, not all of the Dark Matter in the universe. There was a study that also showed that Dark Matter can be explained away by General Relativity.

Hope this answers your question.

P.S. I just wanted to give you some practical ideas regarding antimatter to give you a "broader" perspective and not put it in the same elusive category of dark matter.

Antimatter:
I noticed people keeping saying antimatter is "strange" and the idea is presented that antimatter is exotic and scarce and quite possibly unnatural. Even Superman points out that we make it in very small quantities within particle accelerators. But antimatter is created naturally, every second, in the center of our sun (and all other stars). Stars burn through their material through the process of nuclear fusion. Without antimatter, our sun would not work as it does now.

Fusion reactions in the center of the sun creates antimatter. Imagine this: Two protons just flying around suddenly collide. One result of the collision (there are many) is a proton, neutron, positron, and neutrino.

The positron (anti-electron) finds a lone electron and BAM! they self destruct into high energy photons. Those photons are what gives the sun its heat (energy) and light. The neutrino just high tails it out of there like they always do. Neutrinos don't really interact with anything at all, for the most part.

So now you're left with a proton and neutron, and with their powers combined, becomes a form of hydrogen called deuterium. Just so you know, "normal" hydrogen doesn't have a neutron.

So this happens ALL THE TIME, in natural conditions, not just in a lab. And when hydrogen becomes helium, more antimatter!

Answer 3

Hi. Antimatter is strange because the only difference in the particles is an opposite electric charge - the positron has a positive charge and the anti-proton has a negative charge. I personally do not understand why this difference in charge would cause mutual annihilation if a proton and anti-proton come in contact. No one knows what dark matter is yet.

Answer 4

The Times of India (Oct. 27, 1959) published the following news release:
"Stockholm, Oct. 26, 1959-Two American atomic scientists were awarded the 1959 Nobel Physics Prize today for the discovery of the antiproton, proving that matter exists in two forms—as particles and antiparticles. They are Italian—born Dr. Emillo Segre, 69, and Dr. Owen Chamberlain, born in San Francisco.... According to one of the fundamental
assumptions of the new theory, there may exist another world, or an antiworld, built up of antimatter. This antimaterial world would consist of atomic and subatomic particles spinning in reverse orbits to those of the world we know. If these two worlds should ever clash, they would both be annihilated in one blinding flash."

Dark matter is the existence of great quantities of invisible missing mass. Some astronomers say 90% of the mass of the universe is missing.

Answer 5

Anti-matter refers to subatomic particles that have the opposite properties to the "normal" matter. For instance, a positron is an anti-electron. The positron has the same mass and spin as the electron but has a positive charge. An anti-proton has the same mass and spin as a proton, but is charged negatively. An anti-neutron contains an anti-proton and positron.

We don't really know what dark matter is. Ther eis a lot of it in the universe but since it neither emits nor reflects light, we can't yet say what properties it has other than mass.

Answer 6

Anti-matter is the opposite of matter - what we're made up of. Matter, basically, consists of atoms. They're made up of positively charged Protons and Neutrons in their nucleus, orbited by negatively charged Electrons.

Anti-matter's structure is essentially the same; only, the nucleus is made up of negatively charged anti-Protons, Neutrons, and postively charged positrons orbiting the nucleus.

When an atom of matter and anti-matter meet, they annihilate each other, giving off pure energy, violently.

Dark Matter is *thought* to be some sort of particle that is very massive, creating a lot of gravity, but can't be seen or sensed. They don't really know what it is. But they see the motion of stars inside galaxies, and they're moving far faster than they *should* be. The motion is caused by something giving an immense gravitational force; since they can't see what it is, they've coined it "Dark Matter."

Answer 7

Dark matter has no charge; that's why it's "dark." There's somewhat more to being antimatter than just opposite charge--- it's pretty much opposite *everything*. Every particle has an antiparticle, but some particles (like the photon) don't change when you change everything about it to the opposite, and so they're their own antiparticles.

Answer 8

Anti matter is matter that is opposite in chemical make up to regular matter, IE, a hydrogen atom of normal matter consists of a proton and and electron, its anti matter partner consists of a anti proton and a positron, when the two meet they destroy each other in a burst of energy called a gamma ray. Dark matter is that which reflects no light, science speculates that the mass of this matter makes up 90% of the total mass of the universe, it is a controversial theory becuse the dark matter can't be pin -pointed.

Answer 9

Well antimatter is the opposite of matter. For every single atom etc, there is a completely opposite atom etc somewhere in the universe.
If these two were to touch, there would be a colossal explosion.

Answer 10

"Antimatter" is what causes the letter "h" to disappear from the word "what"!

"Dark matter" is the pre-"liquid paper" method of covering-up such mistakes.

Of course, you forgot the most important one:
"Whatsamatter",
as in "Whatsamatter wid youse
that you can't spell correctly???" ;)