In Search of Antimatter Galaxies August 14, NASA's space shuttle program is winding down. With only a few more flights, shuttle crews will put the finishing touches on the International Space Station ISSbringing to an end twelve years of unprecedented orbital construction.
Currently, the most widely accepted explanation for this observation is the presence of an unidentified dark energy, although several other possibilities have been proposed.
As a new study shows, general relativity predicts that the gravitational interaction between matter and antimatter is mutually repulsive, and could potentially explain the observed expansion of the Universe without the need for dark energy. Although antimatter particles have the opposite electric charge as their associated matter particles, the masses of antimatter and matter particles are exactly equal.
Most importantly, the masses are always positive. For this reason, most physicists think that the gravitational behavior of antimatter should always be attractive, as it is for matter.
However, the question of whether the gravitational interaction between matter and antimatter is attractive or repulsive so far has no clear answer. In the new study, Massimo Villata of the Osservatorio Astronomico di Torino Observatory of Turin in Pino Torinese, Italy, has shown that an answer can be found in the theory of general relativity.
As Villata explains, the current formulation of general relativity predicts that matter and antimatter are both self-attractive, yet matter and antimatter mutually repel each other. On the other side, the cosmological implications of this finding have shown antigravity as an alternative to or explanation of the wooly concept of dark energy for the accelerated expansion of the Universe.
But as Villata explains, there is more than just mass involved in gravity. In this case, time and parity are involved. The idea is based on the concept that all physical laws have CPT charge, parity, and time symmetry.
CPT symmetry means that, in order to transform a physical system of matter into an equivalent antimatter system or vice versa described by the same physical laws, not only must particles be replaced with corresponding antiparticles C operationbut an additional PT transformation is also needed.
From this perspective, antimatter can be viewed as normal matter that has undergone a complete CPT transformation, in which its charge, parity and time are all reversed.
Even though the charge component does not affect gravity, parity and time affect gravity by reversing its sign.
So although antimatter has positive mass, it can be thought of as having negative gravitational mass, since the gravitational charge in the equation of motion of general relativity is not simply the mass, but includes a factor that is PT-sensitive and yields the change of sign. As Villata explains, CPT symmetry means that antimatter basically exists in an inverted spacetime the P operation inverts space, and the T operation inverts time.
He gives the following analogy: But if an anti-apple falls on the normal Earth, or a normal apple falls on an anti-Earth, then the result is different. In both cases, a minus sign arises in the equation of motion, which reverses the gravitational interaction between the anti-apple and Earth, or apple and anti-Earth, making it repulsive.
Whenever matter and antimatter meet, they annihilate and produce photons. But if matter and antimatter repel each other, then they would tend to isolate themselves apart from each other and not annihilate. The force of this matter-antimatter repulsion could explain why the Universe is expanding at an accelerating rate, eliminating the need for dark energy and possibly dark matter.
Villata suspects that antimatter could exist in the Universe in large-scale voids that have been observed in the distribution of galaxy clusters and superclusters.
With diameters of tens of megaparsecs about a hundred million light yearsthese voids are the largest structures in the Universe.
The problem is that, so far, researchers have not observed antimatter in these locations.
Villata plans to investigate this question in a future study on the invisibility of antimatter in voids. WellsThe Dark Arrow of Time, which is currently published only in Italian La freccia oscura del tempobut I hope to find an English publisher soon. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.(The cancer-treatment experiments that Miller et al were almost certainly thinking of when they invented the meson gun - which deposit almost all their energy in brain tumors without depositing much in the intervening tissue - work because they use charged mesons, which (like all charged particles) initially deposity little energy as they pass.
Antimatter and matter particles have the same mass but differ in properties such as electric charge and spin. The Standard Model predicts that gravity should have the same effect on matter and antimatter; however, this has yet to be seen.
Although antimatter particles have the opposite electric charge as their associated matter particles, the masses of antimatter and matter particles are exactly equal.
Mater and antimater are. There is an "origins of life" model, when the first "such and such" appeared, how long they continued, etc., typically given with a time scale (3 to 5 billion years), itself matched to a geological record charted out in eras and periods (ie Jurassic, Paleozoic) which few .
Antimatter, substance composed of subatomic particles that have the mass, electric charge, and magnetic moment of the electrons, protons, and neutrons of ordinary matter but for which the electric charge and magnetic moment are opposite in sign.
AntimatterDec. 1, Antimatter is a large subject which is covered through all the science fields. Antimatter or antiparticles is often called the "mirror image" of ordinary matter. For every type of ordinary matter particle, an antimatter particle can be created that is identi.