For years physicists have posed theories that have tried to explain why the universe doesn’t just fly apart, given what appears to be quite a bit of empty space between star systems, planets and galaxies.
As it is, all the visible objects in the universe are moving away from each and at accelerating rates, over time.
Indeed, the Big Bang theory posits an initial explosion of matter infinitesimally dense. For the past so many billions of years that explosion has emitted matter and particles.
What we see is evidence of that initial event, according to scientists.
But how does one account for the fact that universe still “stays together”, more or less?
Since at least 1933, when Fritz Zwicky, a Swiss astrophysicist, posited that “dark matter” must exist, many assume that there must be invisible matter to account for gravitational forces that keep things from flying apart as galaxies rotate.
For years there’s been no evidence that such matter actually exists.
However, earlier this month a project that is part of the earth’s space station seems to have provided an indirect indication of dark matter’s existence.
The Alpha Magnetic Spectrometer (AMS) has been at the International Space Station since 2011.
The head of the project presented initial findings at CERN, the world’s principal particle-physics laboratory outside Geneva.
AMS consists of a large magnet and sensors to track the path of charged particles or cosmic rays produced by the universe.
Physicists hypothesize that dark matter is comprised of particles called neutralinos, which are the lightest of the super-symmetric particles assumed to exist in dark matter.
Neutralinos have a mass equivalent to that of a few hundred protons. Because they do not interact with light, they are invisible, so the theory goes.
The AMS project is geared to detect the byproduct of the collisions of neutralinos. According to theory, when neutralinos collide they should destroy each other. The byproduct of that collision is the production of electrons and positrons.
Cosmic rays from sources other than neutralino collisions have high amounts of electrons compared to positrons.
However, again, based on theory, when neutralinos collide, a greater amount of positrons relative to electrons is produced.
In addition, the level of positrons drops off rapidly following such events.
According to the report issued by CERN, thus far, since its launch in 2011, AMS has recorded 30 billion cosmic rays.
Interestingly, AMS did detect higher levels of positrons compared to what it would normally detect in cosmic rays not associated with neutralino collisions.
Moreover, AMS found these positron spikes to be evenly distributed, regardless of the direction in which AMS was pointed compared to earth; this seems to be consistent with the theory of dark matter.
However, a possible cause of the increase in the number of positrons might be the result of pulsars, a highly magnetized, rotating neutron star that emits a beam of electromagnetic radiation.
Whether, in fact, dark matter exists as theory posits, there must be forces and matter that keep things from moving away even faster than they already do.
Still, even if dark matter does exist, will it be enough to contract everything into a tiny, incredibly dense point so many billions of years from now?