- 3339 - SPACETIME - are wormholes real? I know what time it is, but, I don’t know what time is. Time is a mystery. We think it is part of space, but we don’t know what space is either? We even stitch them together into a fabric called spacetime. And then spacetime can go down a wormhole. What in the world is that?
--------------------- 3339 - SPACETIME - are wormholes real?
- The fabric of space-time is a conceptual model combining the three dimensions of space with the fourth dimension of time. “Space-time” explains the unusual relativistic effects that arise from traveling near the speed of light as well as the motion of massive objects in the universe, like planets and stars.
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- Albert Einstein helped develop the idea of space-time as part of his theory of relativity. Prior to his pioneering work, scientists had two separate theories to explain physical phenomena. Isaac Newton's laws of physics described the motion of massive objects in space. James Clerk Maxwell's electromagnetic models explained the properties of light.
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- Some experiments conducted at the end of the 19th century suggested that there was something special about light. Measurements showed that light always traveled at the same speed, no matter what.
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- In 1898, the French physicist and mathematician Henri Poincaré speculated that the velocity of light might be an unsurpassable limit. Researchers were considering the possibility that objects changed in size and mass, depending on their speed.
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- Einstein pulled all of these ideas together in his 1905 “theory of special relativity“, which postulated that the speed of light was a “constant“. For this to be true, space and time had to be combined into a single framework that conspired to keep light's speed the same for all observers. Velocity is space (distance) divided by time. Light’s velocity is 186,000 miles per second.
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- A person in a superfast rocket will measure time to be moving slower and the lengths of objects to be shorter compared with a person traveling at a much slower speed. That's because space and time are relative. They depend on an observer's speed. But the speed of light is more fundamental than either space or time.
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- The conclusion that space-time is a single fabric wasn't one that Einstein reached by himself. That idea came from German mathematician Hermann Minkowski, who said in 1908: "Henceforth space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality."
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- The space-time he described is still known as ‘Minkowski space-time” and serves as the backdrop of calculations in both relativity and quantum-field theory.
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- When people talk about space-time, they often describe it as resembling a sheet of rubber. Einstein realized as he developed his theory of general relativity that the force of gravity was due to curves in the “fabric of space-time“. The rubber being the fabric.
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- Massive objects create distortions in space-time that cause it to bend. These curves, in turn, constrict the ways in which everything in the universe moves, because objects have to follow paths along this warped curvature. Motion due to gravity is actually motion along the twists and turns of space-time.
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- The simplest way to understand the fabric of space-time is to imagine a curved sheet of rubber that directs how everything in the universe moves. But the analogy isn't entirely accurate because space-time has four dimensions, while a sheet of rubber only has two dimensions.
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- The analogy eventually breaks down. A rubber sheet is two dimensional, while space-time is four dimensional. It's not just warps in space that the sheet represents, but also warps in time.
- Despite its intricacy, relativity remains the best way to account for the physical phenomena we know about. Yet scientists know that their models are incomplete because relativity is still not fully reconciled with “quantum mechanics“, which explains the properties of subatomic particles with extreme precision but does not incorporate the force of “gravity“.
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- Quantum mechanics rests on the fact that the tiny bits making up the universe are discrete, or quantized. So photons, the particles that make up light, are like little chunks of light that come in distinct packets.
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- Some theorists have speculated that perhaps space-time itself also comes in these quantized chunks, helping to bridge relativity and quantum mechanics.
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- A “wormhole” is a special solution to the equations describing Einstein's theory of general relativity that connects two distant points in space or time via a tunnel. Ideally, the length of this tunnel is shorter than the distance between those two points, making the wormhole a kind of shortcut.
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- Wormholes are legitimate solutions to general relativity, but scientists have never figured out a way to maintain a stable wormhole in the real universe. The simplest possible wormhole solution was discovered by Albert Einstein and Nathan Rosen in 1935, which is why wormholes are sometimes called "Einstein-Rosen bridges.
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- Einstein and Rosen started with the mathematical solution of a blackhole, which consists of a singularity (a point of infinite density) and an event horizon (a region surrounding that singularity beyond which nothing can escape). They found that they could extend this solution to include the polar opposite of blackholes: whiteholes.
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- These hypothetical whiteholes also contain a singularity, but they operate in reverse to a blackhole. Nothing can enter the event horizon of a whitehole, and any material inside the whitehole gets ejected immediately.
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- Einstein and Rosen found that, theoretically, every blackhole is paired with a whitehole. Because the two holes would exist in separate places in space, a tunnel, a wormhole, would bridge the two ends.
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- In order to travel through a wormhole, that tunnel in space-time must be stable.
However, a wormhole created from a pair of black and white holes wouldn't be very useful. For one, white holes would be unstable.
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- If you were to drop a particle toward the event horizon of a whitehole, the particle would never reach the event horizon, because nothing can enter a whitehole. So the energy of the system would continue to increase to infinity, eventually blowing up the whitehole.
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- The only way to enter this kind of wormhole would be to cross the event horizon of the blackhole on the other side. But once an object crossed the event horizon, it could never leave. So objects could enter the wormhole but never escape.
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- A single photon, or particle of light, passing through the wormhole tunnel would introduce so much energy to the system that the tunnel would snap apart, destroying the wormhole.
In the 1970s, however, physicists worked out the math needed to make a stable, or "traversable," wormhole. The trick is to move the entrance of the wormhole tunnel beyond the event horizon of the blackhole and to stabilize the tunnel itself so that matter passing through doesn't cause immediate catastrophic collapse.
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- The key ingredient for stabilizing wormholes is so-called exotic matter, or some form of matter that has negative mass. Unfortunately for such wormholes, scientists have never found evidence for negative mass, and it would violate conservation of momentum, which states that the momentum should remain constant if no force is applied; a negative-mass object placed next to a positive-mass object would immediately accelerate, with no source of energy.
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- If such a wormhole did exist the entrance would be a sphere, like the surface of a planet. If you looked into it, you would see light coming in from the other side. The wormhole tunnel could be any length, and while traveling down the tunnel, you would see distorted views of the region of the universe you came from and the region you were traveling to. I have had this sensation after having too much to drink.
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- A wormhole could also act as a time machine. Special relativity dictates that moving clocks run slowly. Someone racing around at nearly the speed of light would not advance into their own future as quickly as someone standing still.
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- If scientists could somehow construct a wormhole, initially the two ends would be synchronized in time. To travel back in time, you'd simply walk through one end. When you exited the wormhole, you would be in your own past.
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- Wormholes might occur naturally at microscopic scales in the quantum foam.
Even though there is currently no known way to construct a wormhole, and wormholes are purely hypothetical. Although exotic matter is unlikely to exist, there may be another way to stabilize wormholes: negative energy.
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- The vacuum of space-time is filled with quantum fields, the fundamental quantum building blocks that give rise to the forces and particles that we experience, and these quantum fields have an intrinsic amount of energy.
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- It's possible to construct scenarios in which the quantum energy in a particular region is lower than its surroundings, making that energy negative at a local level. Such negative energy exists in the real world in the form of the “Casimir effect“, in which the negative quantum energies between two parallel metal plates cause the plates to attract.
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- But no one knows if this negative quantum energy can be used to stabilize a wormhole. It may not even be the "right" kind of negative energy, since it's only negative relative to its surroundings, not in an absolute way.
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- Wormholes might occur naturally at microscopic scales in the quantum foam, the roiling nature of space-time at the very tiniest of scales due to those same quantum energies.
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- In that case, wormholes might be popping in and out of existence constantly. So much for the theory of wormholes. Even more mysterious than blackholes. Theories can go anywhere. Evidence is harder to find. Confirming evidence even harder.
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November 12, 2021 SPACETIME - are wormholes real? 3339
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