![]() In this case, its ultimate fate is the "Big Freeze" followed by the "Big Rip": first, the universe's outward acceleration would tear galaxies and stars apart, leaving all matter frigid and alone. If there is no dark energy, such a universe would eventually stop expanding and would instead start contracting, eventually collapsing in on itself in an event dubbed the "Big Crunch." If the universe is closed but there is dark energy, the spherical universe would expand forever.Īlternatively, if Ω is less than 1, then the geometry of space would be "open" like the surface of a saddle. If Ω is greater than 1, then space-time would be "closed" like the surface of an enormous sphere. ![]() The fate of the universe strongly depends on a factor of unknown value: Ω, a measure of the density of matter and energy throughout the cosmos. (Image credit: Creative Commons Attribution-Share Alike 3.0 Unported | Bjarmason) Next Up: Fate of the universe What is the fate of the universe? ![]() The most detailed test to date of the differences between matter and antimatter, announced in August 2015, confirm they are mirror images of each other, providing exactly zero new paths toward understanding the mystery of why matter is far more common. For this, there is no accepted explanation. For some reason, there was excess matter that didn't get annihilated, and here we are. But if that had happened, there would have been a total annihilation of both: Protons would have canceled with antiprotons, electrons with anti-electrons (positrons), neutrons with antineutrons, and so on, leaving behind a dull sea of photons in a matterless expanse. One assumes the universe would treat matter and antimatter symmetrically, and thus that, at the moment of the Big Bang, equal amounts of matter and antimatter should have been produced. The question of why there is so much more matter than its oppositely-charged and oppositely-spinning twin, antimatter, is actually a question of why anything exists at all. Antimatter Why is there more matter than antimatter? Is there something wrong with that logic, or is its bizarre outcome true? And if it is true, how might we ever detect the presence of parallel universes? Check out this excellent perspective from 2015 that looks into what "infinite universes" would mean. This means there are infinitely many parallel universes: cosmic patches exactly the same as ours (containing someone exactly like you), as well as patches that differ by just one particle's position, patches that differ by two particles' positions, and so on down to patches that are totally different from ours. So, with an infinite number of cosmic patches, the particle arrangements within them are forced to repeat - infinitely many times over. If so, then the region we can see (which we think of as "the universe") is just one patch in an infinitely large "quilted multiverse." At the same time, the laws of quantum mechanics dictate that there are only a finite number of possible particle configurations within each cosmic patch (10^10^122 distinct possibilities). The best researchers have been able to do in recent years is narrow in a bit on where dark energy might be hiding, which was the topic of a study released in August 2015.Īstrophysical data suggests space-time might be "flat," rather than curved, and thus that it goes on forever. Based on the observed rate of expansion, scientists know that the sum of all the dark energy must make up more than 70 percent of the total contents of the universe. As space expands, more space is created, and with it, more dark energy. In the most widely accepted model of dark energy, it is a "cosmological constant": an inherent property of space itself, which has "negative pressure" driving space apart. To account for this, astrophysicists have proposed an invisible agent that counteracts gravity by pushing space-time apart. ![]() Even though gravity is pulling inward on space-time - the "fabric" of the cosmos - it keeps expanding outward faster and faster. No matter how astrophysicists crunch the numbers, the universe simply doesn't add up.
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