11bn-year-old diamond the size of Earth is coldest white dwarf ever discovered




4
Times Points Earned

past incarnation of the time travelling photon”,

TIME TRAVEL TEST finds black holes needed to make photons flit

We don' need no steenkin' causality*



IF REINCARNATION IS TRUE WE ALL HAVE TO TIME TRAVEL THROUGH A DARK TUNNEL TO REACH THE LIGHT AT THE OTHER END


The Boy Who Lived Before - YouTube

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Cameron, ever since he was just a toddler, talks about another family he used to live with, called the ...
  • Time Travel
  • Quantum Mechanics
  • Queensland University
  • Andrew Whitebr />
    University of Queensland researchers have doubled-down on the question of whether quantum mechanics can exhibit “time travel” behaviours, producing a simulation of time travel using a single photon following a “closed timelike curve” (CTC).
    No, it's not actually time travel. Rather, the UQ
    work is looking at what we can predict about quantum systems if time travel ever does exist, based on the behaviour of a very simple two-photon quantum computer.
    (CTCs don't actually exist so far as we've observed, they're just predictions of the field equations in general relativity - making them an interesting field of study for physicists.)
    The UQ boffins have produced a two-photon simulation designed not to execute "time travel", but to try and test predictions of what happens to quantum mechanics if a quantum could be induced to traverse a CTC. It turns out that things we're used to in quantum mechanics in the non-relativistic world break "in really interesting ways", as UQ professor Andrew White told The Register.
    The work is published in Nature, here.
    The "right conditions" to get a quantum to traverse a CTC aren't likely to exist any time soon: White said we'd need to put quantum systems in the presence of “strongly relativistic” effects like being near black holes – and so far, such conditions haven't been found on Earth.
    Instead, “the time-travel was simulated by using a second photon to play the part of the past incarnation of the time travelling photon”, according to University of Queensland PhD student Martin Ringbauer.
    How does this demonstrate time travel? According to The Speaker, Ringbauer said, the mathematical equivalence between two different time-travel “cases” is the key.
    In the first case, the photon travels through a wormhole; but in the second case, the second photon “travels through normal space-time, but interacts with another photon that is trapped inside a CTC forever”. The second case, he said, is the mathematical equivalent of the first in quantum mechanical terms – so it permits study of the “wormhole case”.

    How to simulate time travel

    To untangle all of this, professor White explained to Vulture South that since the late 1980s, quantum physicists have asked what would happen if quanta, rather than “classical-scale” objects, found themselves in CTCs.
    Closed timelike curves, predicted in general relativityWant a time machine? First, catch your wormhole. Image: Martin Ringbauer
    This could be tested a couple of ways, he said: since quantum mechanics works on probabilities, you could design an experiment “so that what goes into the time machine has the same probabilities as what comes out”.
    Or, since quantum mechanics predicts wave functions of quanta, you could see if the wave function coming out of the “time machine” matches the wave function going in.
    It's the second kind, the wave function match across time by a single quantum (predicted by physicist David Deutsch, White said), that they sought to test.
    The kit they used is familiar in any university quantum computing laboratory. By shining a bright laser through nonlinear crystals, the lab generated photon pairs, which were passed through a linear optic entangling gate. The measurements are then made by (again familiar) single photon counting modules.
    Typically, White said, if photons are in states 90° apart they're easy to distinguish, but at 45° apart they're almost impossible to distinguish. However, by applying the “time machine” of “Deutsche's equivalency” to the photon pairs, “we were able to distinguish the states at 45° every time”.
    The implications of the work are probably esoteric for now, White said. For example, what they've been able to demonstrate is that in the presence of a time machine, the “no-cloning” theorem that prevents the perfect copying of quantum states breaks down.
    No-cloning is part of the basis of quantum cryptography (you can't copy the state of the quantum that's carrying a key from Alice to Bob, without destroying the state you copy and letting Alice and Bob know you're there), as well as quantum computing.
    In other words, in the presence of strong relativistic effects, White said, quantum crypto, quantum computing – and Heisenberg's uncertainty theorem, except this poor hack doesn't quite understand why – can all break down.
    As already noted, humans are unlikely to encounter sufficiently strong relativistic fields any time soon. White noted that one of the suggestions for creating a closed timelike curve would be to get three black holes, line them up, and start them spinning.
    So our quantum crypto is safe for now, at least. ®
    *Bootnote: Actually, causality is also safe. But why waste a chance at a fun sub-headline?
    Causality is a funny thing in quantum systems. Even though general relativity doesn't forbid time travel at a macro level, the "grandfather paradox" (killing your own grandfather so you aren't born so you can't kill your grandfather) appears to suggest it can't happen.
    Quanta can exist in superpositions of states, which alleviates the problem considerably: you could, analogously, both kill your grandfather and not kill your grandfather. No causality paradox to worry about! ®

more questions than answers.



Higgs boson scientists: The universe should have collapsed

The science and astrophysics community was ecstatic with the discovery of the Higgs Boson in July of 2012, but two years later the physics its discovery has exposed shows the universe shouldn’t exist.

By Ryan Johnson, Daily Digest News
Tuesday, June 24, 2014



Last year’s discovery of the Higgs boson was thought to answer a number of questions regarding how particles derive their mass. Now, however, it seems the discovery of the elusive particle is raising more questions than answers.
Physicists at King’s College in London now say they have recreated conditions for the Big Bang now with the information from the discovery of the Higgs boson, and they report that the universe should have expanded too quickly and collapsed.
“During the early universe, we expected cosmic inflation — this is a rapid expansion of the universe right after the Big Bang,” said study co-author Robert Hogan, a Ph.D. student in physics at King’s College in London. “This expansion causes lots of stuff to shake around, and if we shake it too much, we could go into this new energy space, which could cause the universe to collapse.”
While the data shows the universe should not exist, it clearly does, leading some to question exactly how the findings should be interpreted.
“We are here talking about it,” Hogan told Live Science. “That means we have to extend our theories to explain why this didn’t happen.”
A telescope in the Antarctic called Background Imaging of Cosmic Extragalactic Polarization (BICEP¬2) –so named for its extraordinary detection capabilities —is believed to have detected slivers of cosmic inflation in background microwave radiation that permeates the universe. The data collected by BICEP¬2 could provide further evidence as to why the Big Bang occurred and why the universe remains stable.
Already some scientists have put forth theories as to how to interpret the Higgs data. One theory holds that supersymmetry, the theory that all currently known particles have superpartner particles, may be partly responsible. Hogan believes with more powerful particle accelerators—more intense than the Large Hadron Collider which found the Higgs Boson—these particles may one day be discovered.
The discovery of the Higgs Boson has already led to many apocalyptic visions by researchers, who believe out of its fundamental instability, the universe should collapse in a few billion years. For now, scientists will have to mold and adapt their theories to explain why we’ve been here for the first 13.8 billion years.