Dark matter may be an illusion caused by the quantum vacuum

moejoe15

http://www.physorg.com/news/2011-08-...um-vacuum.html

"His ideas (like those in the previous paper) rest on the key hypothesis that matter and antimatter are gravitationally repulsive, which is due to the fact that particles and antiparticles have gravitational charge of opposite sign. (Though like matter, antimatter is gravitationally attractive with itself.)"

If this were true is it possible there are antimatter galaxies? Could we tell if a galaxy was antimatter?

Chronos

I guess we will know soon enough - e.g.,
http://arxiv.org/abs/1106.0209
AEGIS at CERN: Measuring Antihydrogen Fall
ABSTRACT: The main goal of the AEGIS experiment at the CERN Antiproton Decelerator is the test of fundamental laws such as the Weak Equivalence Principle (WEP) and CPT symmetry. In the first phase of AEGIS, a beam of antihydrogen will be formed whose fall in the gravitational field is measured in a Moire' deflectometer; this will constitute the first test of the WEP with antimatter.

The nutjobs are already rattling their free energy sabers over this. An anti gravity result would be . . . one of the most astounding discoveries in the history of physics [i.e., it's incredibly improbable].

CosmicEye

I always wondered if you held a lb of antimatter in your hand while standing on a scale, would you be a lb lighter?

Also, if antimatter existed, wouldnt it anhialate regular matter? I dont know much of this subject. Dark Matter is so confusing to understand!

Pengwuino

Anti-matter exists and we've known about it for decades and they pop up in every high energy experiment done. There's nothing mysterious or unknown about anti-matter outside of a few questions such as the gravitational one and various theoretical issues.

Yes, anti-matter would annihilate with regular matter. So if you grabbed a pound of anti-matter, you're going to explode in an explosion equivalent to some of the biggest thermonuclear weapons ever tested long before you figure out what the gravitational effects would be ;).

If you pretended it didn't explode, you would weigh less... but at the same time the anti-matter would probably try to get away from you just like electric charges of similar polarity would try to separate.

ibysaiyan

Go through the search function,there's ample amount of information on this sub-forum dealing with the hypothetical DM. It's difficult to understand although which is ironic considering the universe is composed of roughly 23% of it, however it could be less dense at certain regions compared to others.

From what I can recall they're mainly put down into two distinct catagories: WIMP and MACHOS (I think the consensus of the scientific community is increasingly against it ? discarded).The reason why it's tricky is due to it's interaction with gravity only other then the that it's present mainly around regions where we would least expect them to be around (for example: In spiral galaxies they are theorized to answer the nearly non-existing difference in radial velocities at the visible galactic disc/bulge and the furthest part].


-ibysaiyan

IsometricPion

Why would it try to get away? The composition of the antimatter was not specified, if it were composed of, e.g., anti-hydrogen it would be neutral on macroscopic scales. So, the issue of its weight would be entirely decided by its gravitational attraction to (or repulsion from) normal matter.

moejoe15

The reason I ask this is that if antimatter has opposite gravity (I like the yin/yang of the theory) clumps would form of both types of matter, galaxies, and repel each other possibly maintaining the formation of the universe with equal amounts of both. They wouldn't have been able to annihilate each other. Could it also explain the expansion of the universe if there is an even distribution of matter and antimatter galaxies? Can't wait to hear the results of that experiment.

Dotini

Apparently you may be able to manipulate or exploit it if you first held it confined in a magnetic bottle. And you wouldn't have to go far to acquire antimatter to experiment with, as it's permanently trapped in a magnetic belt around Earth. Some folks may already be scheming to harvest its energy.

http://www.bbc.co.uk/news/science-environment-14405122
http://www.niac.usra.edu/files/studi...71Bickford.pdf

A thin band of antimatter particles called antiprotons enveloping the Earth has been spotted for the first time.

The find, described in Astrophysical Journal Letters, confirms theoretical work that predicted the Earth's magnetic field could trap antimatter.

The team says a small number of antiprotons lie between the Van Allen belts of trapped "normal" matter.

The antiprotons were spotted by the Pamela satellite (an acronym for Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) - launched in 2006 to study the nature of high-energy particles from the Sun and from beyond our Solar System - so-called cosmic rays.

The new analysis, described in an online preprint, shows that when Pamela passes through a region called the South Atlantic Anomaly, it sees thousands of times more antiprotons than are expected to come from normal particle decays, or from elsewhere in the cosmos.

Dr Bruno said that, aside from confirming theoretical work that had long predicted the existence of these antimatter bands, the particles could also prove to be a novel fuel source for future spacecraft - an idea explored in a report for Nasa's Institute for Advanced Concepts.

Respectfully submitted,
Steve

AndromedaRXJ

So anti-matter and negative matter might be the same thing? I've heard that before.

Well if it's not, and negative matter exists as only negative matter, then I'm sure there's negative anti-matter =P

Chronos

The graviton is believed to be a spin 2 particle in the the particle scheme of things. I fail to see how it can have an anti particle.

CosmicEye

Well of course assuming it wouldnt blow a crater in the side of the Earth holding a pound of AM. From what sounds logical, AM wouldnt have more energy than regular matter, its when the 2 combine that makes explosive amounts of energy. But hey that just my idea of how it works. I wish I knew more about it.

Thanks for the post ibysaiyan.

moejoe15

I am more interested in the implications of the theory, some of which I mentioned.

Another implication of there still being almost equal amounts of matter and antimatter in our present universe is that there could be small chunks of it floating around in our galaxy.

This might explain a couple of things. An intelligent race that has achieved space travel would eventually be able to obtain it and use it as a source of power. It has been speculated before that if UFO's exist they need a high power source like antimatter but the energy required to make it is prohibitive, so where would they get it? Not a problem if it already exists. I am assuming that even if it has opposite gravity that small amounts would be relatively unaffected by our gravity since gravity is such a weak force.

It might also explain the Tanguska event. It probably wouldn't take much antimatter to produce that explosion.

omoplata

If antimatter is gravitationally repelled by matter, wouldn't earth repel antimatter asteroids? I guess it would be like coulomb scattering on a bigger scale. The antimatter asteroid would have to approach earth very fast to make contact at all. I was curious about this and searched wikipedia. It doesn't say anything about the gravitational repulsion, but it says if a clump of antimatter fell on the earth, it would have annihilated up high above the atmosphere and wouldn't get as low as the epicentre of the Tunguska event.

moejoe15

I would think not. The force of gravity is weak and for small objects it would be almost negligible relative to their velocity which could be the same relative to the earth as regular meteorites, about 40,000 mph (maybe a lot more considering where they are coming from). Also the amount of antimatter required for the Tanguska explosion would be very small (less than a pound?). The amount of repulsive force on something that size at high velocity would not affect its trajectory very much.

The repulsive force could keep regular matter from interacting with antimatter as it enters the atmosphere. That article didn't take into account the possibility of antigravity antimatter.

Ken G

The idea here is not that there is a bunch of antimatter floating around, and certainly not that there is the same amount of antimatter as normal matter. Instead, the idea is that there is both virtual antimatter, and virtual matter, popping in and out of existence almostly instantly but staying around only long enough that it can get polarized by the gravity of the real matter. So it's a kind of vacuum modification to real gravity. What I don't get is how it could be relevant on the large scales of a galaxy but not the small scales of a solar system. Certainly the dielectric analogy would not satisfy that constraint, so either his calculations involve more than was reported in that article, or they are not so well thought out.

moejoe15

Maybe, but if the theory is true and there was initially equal amounts of both matter and antimatter as some theories suggest, they would interact differently in the beginning. I would think that this would affect the quantities of both in the present universe.