Are there other dimensions

Some researchers base their ideas of parallel universes on quantum mechanics, the mathematical description of subatomic particles. In quantum mechanics, multiple states of existence for tiny particles are all possible at the same time — a "wave function" encapsulates all of those possibilities. However, when we actually look, we only ever observe one of the possibilities.

According to the Copenhagen interpretation of quantum mechanics as described by the Stanford Encyclopedia of Philosophy , we observe an outcome when the wave function "collapses" into a single reality. But the many-worlds theory proposes instead that every time one state, or outcome, is observed, there is another "world" in which a different quantum outcome becomes reality. This is a branching arrangement, in which instant by instant, our perceived universe branches into near-infinite alternatives.

Those alternate universes are completely separate and unable to intersect, so while there may be uncountable versions of you living a life that's slightly — or wildly — different from your life in this world, you'd never know it. The many-worlds theory is the most "courageous" take on the quandary of quantum mechanics, physicist Sean Carroll wrote in his book, " Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime " Dutton, He also argued that it is the most straightforward theory, although not without wrinkles.

One of those wrinkles is that the many-worlds idea is not really falsifiable. This is an important component of scientific thought and is the way the scientific community develops ideas that can be explored with observation and experimentation. If there's no opportunity to find evidence against a theory, that's bad for science as a whole, science journalist John Horgan argued in a blog post for Scientific American.

Some physicists believe in a flatter version of multiple universes. That is, if the universe that we live in goes on forever, there are only so many ways that the building blocks of matter can arrange themselves as they assemble across infinite space. Eventually, any finite number of particle types must repeat a particular arrangement. Hypothetically, in a big enough space, those particles must repeat arrangements as large as entire solar systems and galaxies.

So, your entire life might be repeated elsewhere in the universe, down to what you ate for breakfast yesterday. At least, that's the theory. But if the universe began at a finite point, as nearly every physicist agrees that it did, an alternate version of you likely doesn't exist, according to astrophysicist Ethan Siegel's Medium article. According to Siegel, "the number of possible outcomes from particles in any Universe interacting with one another tends towards infinity faster than the number of possible Universes increases due to inflation.

In a relatively recent addition to the pantheon of multiverse theories, researchers from the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, have proposed that the universe began at the Big Bang — and on the opposite side of the Big Bang timeline, stretching backwards in time, a universe once existed that was the exact mirror image of our own.

That means everything — protons, electrons, even actions like cracking an egg — would be reversed. Antiprotons and positively charged electrons would make up atoms, while eggs would un-crack and make their way back inside chickens.

Eventually, that universe would shrink down, presumably to a singularity, before expanding out into our own universe. Seen another way, both universes were created at the Big Bang and exploded simultaneously backward and forward in time. The fact that we still exist is one circumstantial piece of evidence that other dimensions are ultra-tiny.

The team calculated that they must be smaller than 16 nanometers, too small for their gravity to influence much in our world and hundreds of times smaller than previous calculations, Grossman reports. The new study comes on the tail of another study about extra dimensions published in the Journal of Cosmology and Astroparticle Physics published in July. Mara Johnson-Groh at LiveScience reports that one of the big questions in physics is why the expansion of the universe is accelerating.

One theory is that gravity is leaking out of our universe into other dimensions. The Universe has been expanding ever since the Big Bang, but what is it expanding into? The laws of physics and our own experience of time do not always see eye to eye. The Universe has a speed limit and it seems there is no way around it. Can spilling our tea teach us why earthquakes can be so destructive?

Many theories for what could be beyond the Universe are truly mind-bending. It may seem obvious, but the dark sky tells us a lot about the Universe. This one cataclysmic event gave rise to our entire Universe.