How do parallel universes work

A finite Universe would display a number of telltale signals that enable us to determine that we don't live in an infinite sea of spacetime. We'd measure our spatial curvature, and could find that the Universe was shaped like a sphere in some way, where if you traveled in a straight line for long enough, you'd return to your starting point. You could look for repeating patterns in the sky, where the same object appeared in different locations simultaneously.

You could measure the Universe's smoothness in temperature and density, and see how those imperfections evolved over time. If the Universe were finite, we would see a specific set of properties inherent to the patterns that the Big Bang's leftover temperature fluctuations displayed.

But what we see instead are a different set of patterns, teaching us the exact opposite: the Universe is indistinguishable from being perfectly flat and infinitely large. The appearance of fluctuations in the CMB with differing angular sizes would point to different Presently, the Universe appears to be flat, but we have only measured down to about the 0.

Of course, we can't know that for certain. If all you had access to was your own backyard, you couldn't measure the curvature of the Earth, because the portion you had access to was indistinguishable from flat. Based on the portion of the Universe we see, we can state that if the Universe is finite and does curve back on itself, it must have at least millions of times the volume of the portion we can see, with no upper limit to that figure.

But theoretically, the implications of our observations paint a picture that's even more tantalizing. You see, we can extrapolate the Big Bang backwards to an arbitrarily hot, dense, expanding state, and find that it couldn't have gotten infinitely hot and dense early on. Rather, above some energy and before some very early time, there was a phase that preceded the Big Bang, set it up, and led to the creation of our observable Universe.

From the end of inflation and the start of the hot Big Bang, we can trace out our cosmic history. This is the consensus view of how our Universe began, but it is always subject to revision with more and better data.

That phase, a period of cosmological inflation, describes a phase of the Universe where rather than being full of matter and radiation, the Universe was filled with energy inherent to space itself: a state that causes the Universe to expand at an exponential rate. In a Universe filled with matter or radiation, the expansion rate will decrease over time, as the Universe becomes less dense.

But if the energy in inherent to space itself, the density will not drop, but rather remains constant, even as the Universe expands. In a matter or radiation dominated Universe, the expansion rate slows as time goes on, and distant points recede from one another at ever slower speeds. Note that, in inflation, each time interval that goes by results in a Universe that is doubled in all dimensions from its prior size. This implies:. The simplest model of inflation is that we started off at the top of a proverbial hill, where If that valley isn't at a value of zero, but instead at some positive, non-zero value, it may be possible to quantum-tunnel into a lower-energy state, which would have severe consequences for the Universe we know today.

Inflation occurred for some amount of time in the past, but then ended, setting up the Big Bang. One useful way to think about inflation is like a ball rolling very slowly down from the top of a very flat hill. As long as the ball remains near the topmost plateau, it rolls slowly and inflation continues, causing the Universe to expand exponentially. Once the ball reaches the edge and rolls down into the valley, however, inflation ends.

As it oscillates back-and-forth in the valley, that rolling behavior causes the energy from inflation to dissipate, converting it into matter-and-radiation, ending the inflationary state and beginning the hot Big Bang. It needs to roll down the metaphorical hill and into the valley, but if it's a quantum field, the spreading-out means it will end in some regions while continuing in others.

But inflation doesn't occur everywhere at once and end everywhere at once. Everything in our Universe is subject to the bizarre quantum laws of reality, even inflation itself. Additionally, there are other well-respected physicists who find such problems when faced with the multiverse hypothesis, such as Prof. Paul Davie — a physicist and astrobiologist from the Arizona State University he specializes in the quantum field theory. Davies notes:. First, because we need to explain where the law of laws come from.

Although, in the presence of much scientific skepticism, Prof. Tegmark, gaining much recognition for his work in fields such as cosmology, holds very strongly to the multiverse hypothesis; the link provided below is a carefully constructed paper by Prof. Tegmark, and will provide deeper insight as well as mathematical descriptions of his reasons for arguing in favor of parallel universes.

Care about supporting clean energy adoption? Find out how much money and planet! By signing up through this link , Futurism. Once inflation begins, in fact, it's virtually impossible to stop inflation from occurring in perpetuity at least somewhere.

As time goes on, more Big Bangs — all disconnected from one another — occur, giving rise to an uncountably large number of independent Universes: a multiverse. While many independent Universes are predicted to be created in an inflating spacetime, inflation This is where the scientific motivation for a Multiverse comes from, and why no two Universes will ever collide.

There simply aren't enough Universes created by inflation to hold every possible quantum outcome owing to the interactions of particles within an individual Universe. The big problem for both of these ideas is that there's no way to test or constrain the prediction of these parallel Universes. After all, if we're stuck in our own Universe, how can we ever hope to access another one? We have our own laws of physics, but they come along with a whole host of quantities that are always conserved.

Particles don't simply appear, disappear, or transform; they can only interact with other quanta of matter and energy, and the outcomes of those interactions are similarly governed by the laws of physics. In all the experiments we've ever performed, all the observations we've ever recorded, and all the measurements ever made, we've never yet discovered an interaction that demands the existence of something beyond our own, isolated Universe to explain.

The Standard Model of particle physics accounts for three of the four forces excepting gravity , Unless, of course, you've read the headlines that came out this week , reporting that scientists in Antarctica have discovered evidence for the existence of parallel Universes. If this were true, it would be absolutely revolutionary. It's a grandiose claim that would show us that the Universe as we currently conceive of it is inadequate, and there's much more out there to learn about and discover than we ever thought possible.

Not only would these other Universes be out there, but matter and energy from them would have the capability to cross over to and interact with matter and energy in our own Universe. Perhaps, if this claim were correct, some of our wildest science fiction dreams would be possible. Perhaps you could travel to a Universe:. A representation of the different parallel "worlds" that might exist in other pockets of the So what was the remarkable evidence that demonstrates the existence of a parallel Universe?

What observation or measurement was made that brought us to this remarkable and unexpected conclusion? The ANITA ANtarctic Impulsive Transient Antenna experiment — a balloon-borne experiment that's sensitive to radio waves — detected radio waves of a particular set of energies and directions coming from beneath the Antarctic ice. This is good; it's what the experiment was designed to do! If we were to set off for the edge of our bubble, where it might butt up against the next bubble universe over, we'd never reach it because the edge is zipping away from us faster than the speed of light, and faster than we could ever travel.

Related: How many stars are in the universe? But even if we could reach the next bubble, according to eternal inflation combined with string theory , our familiar universe with its physical constants and habitable conditions could be totally different from the hypothetical bubble universe next to our own.

The rest of the multiverse remains barren, but no one is there to complain about that. Vilenkin's explanation implies that in some of the infinite bubble universes outside our own, there could be other intelligent observers. But in every instant that passes, we get farther away from them, and we will never intersect. 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.