What if you’re somebody’s shadow?

Two days ago, I discussed several theories which call for universes parallel to our own. Brian Greene, writing in Discover Magazine, floats another one even queerer than the three I mentioned. Whereas the other worlds in my last post were causally isolated from our own, this hypothesis posits that all the events in our universe are the “holographic” projection of another distant cosmos. I haven’t given this theory enough benefit of the doubt to even call myself “skeptical” of it yet, but it’s still kind of trippy to think about:

The strangest version of all parallel universe proposals is one that emerged gradually over 30 years of theoretical studies on the quantum properties of black holes. The work culminated in the last decade, and it suggests, remarkably, that all we experience is nothing but a holographic projection of processes taking place on some distant surface that surrounds us. You can pinch yourself, and what you feel will be real, but it mirrors a parallel process taking place in a different, distant reality.

Plato likened our view of the world to that of an ancient forebear watching shadows meander across a dimly lit cave wall. He imagined our perceptions to be but a faint inkling of a far richer reality that flickers beyond reach. Two millennia later, Plato’s cave may be more than a metaphor. To turn his suggestion on its head, reality—not its mere shadow—may take place on a distant boundary surface, while everything we witness in the three common spatial dimensions is a projection of that faraway unfolding. Reality, that is, may be akin to a hologram. Or, really, a holographic movie.

The journey to this peculiar possibility combines developments deep and far-flung—insights from general relativity; from research on black holes; from thermodynamics, quantum mechanics, and, most recently, string theory. The thread linking these diverse areas is the nature of information in a quantum universe.

Physicists Jacob Bekenstein and Stephen Hawking established that, for a black hole, the information storage capacity is determined not by the volume of its interior but by the area of its surface. But when the math says that a black hole’s store of information is measured by its surface area, does that merely reflect a numerical accounting, or does it mean that the black hole’s surface is where the information is actually stored? It’s a deep issue and has been pursued for decades by some of the most renowned physicists. The answer depends on whether you view the black hole from the outside or from the inside—and from the outside, there’s good reason to believe that information is indeed stored at the event horizon. This doesn’t merely highlight a peculiar feature of black holes. Black holes don’t just tell us about how black holes store information. 
Black holes inform us about information storage 
in any context.

Think of any region of space, such as the room in which you’re reading. Imagine that whatever happens in the region amounts to information processing—information regarding how things are right now is transformed by the laws of physics into information regarding how they will be in a second or a minute or an hour. Since the physical processes we witness, as well as those by which we’re governed, seemingly take place within the region, it’s natural to expect that the information those processes carry is also found within the region. But for black holes, we’ve found that the link between information and surface area goes beyond mere numerical accounting; there’s a concrete sense in which information is stored on their surfaces. Physicists Leonard Susskind and Gerard ’t Hooft stressed that the lesson should be general: Since the information required to describe physical phenomena within any given region of space can be fully encoded by data on a surface that surrounds the region, then there’s reason to think that the surface is where the fundamental physical processes actually happen. Our familiar three-dimensional reality, these bold thinkers suggest, would then be likened to a holographic projection of those distant two-dimensional 
physical processes.

If this line of reasoning is correct, then there are physical processes taking place on some distant surface that, much as a puppeteer pulls strings, are fully linked to the processes taking place in my fingers, arms, and brain as I type these words at my desk. Our experiences here and that distant reality there would form the most interlocked of parallel worlds. Phenomena in the two—I’ll call them Holographic Parallel Universes—would be so fully joined that their respective evolutions would be as connected as me and 
my shadow.

I can’t help but wonder what repercussions this theory would have on our discussions of causality, agency, and “free will” if it were proven plausible, let alone true.

It would be a victory for determinists, no doubt, but I can’t imagine what we would do with it. Most contemporary literature by determinists I’ve read has been less concerned with actually proving the reality of physical necessity (for example their failure to really sieze the Rietdijik-Putnam argument is especially striking) with demonstrating we do not have to abandon commonsense moral intuitions with the specious doctrines of libertarianism. But holographic cosmology would surely inspire some interesting papers. I don’t have a clear enough head right now to imagine what they would contain; but it could be a fun thought exercise for Sunday.

Inflationary multiverse theory may have recieved first direct empirical evidence

Democritus, or perhaps Leucippus, was the first Western thinker to propose an infinite universe. Many of Democritus’ commentators in early Greek philosophy, most notably Aristotle, found the hypothesis extravagant. However, numerous strands of 20th century physics suggest Democritus not have gone far enough, and advance a succession of theories positing an infinite number of universes.

Quantum physicists following Hugh Everett argued the jittery indeterminism and anti-realism of quantum mechanics was an illusion, and every possible wave function realized itself in some parallel plane. String theory posited our universe was a four-dimensional membrane or “brane” in an unfathomable stack of cosmic tissue. The inflationary cosmologies of  Guth, Vilenkin, and Linde predict the universe created in our Big Bang is merely one bubble in an inexhaustible foaming spacetime sea.

Now, none of the theories of a multiverse are interchangeable. All posit the existences of universes causally isolated from, but equally real from our own. But each theory posits their own universes exist in a different way from those predicted by other theories. Proving one right would not be a “proof” for another–but it would also not be a refutation of the other two. The theories attempt to describe different phenomena, so aren’t in competition. As they are not mutually exclusive, it is possible to believe in all three without contradicting oneself–though I would not recommend making this leap yet, because it is still something of a leap of faith. The mathematical descriptions of quantum mechanics, string theory, and inflation are all incomplete, and the latter two are still controversial in-of-themselves in their respective fields, regardless of their content on parallel worlds.

And, more importantly, there has been no unambiguous empirical evidence for the existence of any parallel universe, let alone an infinite quantity of them. Quantum physics and inflation have both made mathematical predictions which have been confirmed in observations. This has led some of their defenders to claim that because these theories maths have proved consistent with experiment, they should also vouch for their content which is beyond our current capacity to test. In short, they say because the theories apply to accessible parts of reality have proven true, they are likely true when they speak of the inaccessible parts, too. But this is not solid science. As the English biologist Thomas Henry Huxley said, “Many a beautiful theory was killed by an ugly fact.” Whether the facts compliment the beauty of our best and brightests’ equations has yet to be determined.

However, we may finally have the first solid fact (ugly or otherwise, depending on your commitment to human exceptionalism) to put one multiversal hypothesis to the test. A recent paper in Physical Reviews letter claims to have observed the “shadow” of four other universes created by inflation:

The idea that other universes – as well as our own – lie within “bubbles” of space and time has received a boost. Studies of the low-temperature glow left from the Big Bang suggest that several of these “bubble universes” may have left marks on our own. 

… The preliminary work, to be published in Physical Review D, will be firmed up using data from the Planck telescope. For now, the team has worked with seven years’ worth of data from the Wilkinson Microwave Anisotropy Probe, which measures in minute detail the cosmic microwave background (CMB) – the faint glow left from our Universe’s formation.

The theory that invokes these bubble universes – a theory formally called “eternal inflation” – holds that such universes are popping into and out of existence and colliding all the time, with the space between them rapidly expanding – meaning that they are forever out of reach of one another.

But Hiranya Peiris, a cosmologist at University College London, and her colleagues have now worked out that when these universes are created adjacent to our own, they may leave a characteristic pattern in the CMB.

Dr Peiris’ team first proposed these disc-shaped signatures in the CMB in a paper published in Physical Review Letters, and the new work fleshes out the idea, putting numbers to how many bubble universes we may be able to see now.

Crucially, they used a computer program that looked for these discs automatically – reducing the chance that one of the collaborators would see the expected shape in the data when it was not in fact there.

The program found four particular areas that look likely to be signatures of the bubble universes – where the bubbles were 10 times more likely than the standard theory to explain the variations that the team saw in the CMB.

However, Dr Peiris stressed that the four regions were “not at a high statistical significance” – that more data would be needed to be assured of the existence of the “multiverse”.

“Finding just four patches is not necessarily going to give you a good probability on the full sky,” she explained to BBC News. “That’s not statistically strong enough to either rule it out or to say that there is a collision.”

Dr Peiris said that data from the Planck telescope – a next-generation space telescope designed to study the CMB with far greater sensitivity – would put the idea on a firmer footing, or refute it. However, the data from Planck cannot be discussed publicly before January 2013.

So, things to stay alive through 2013 for: Cabin in the Woods, The Avengers,  and evidence for or against a multiverse.

Further reading suggestion:  Many Worlds in One, by Alex Vilenkin, father of eternal infation. A popular, accessible, and funny, but by no means breezy, exposition of the theory Peiris and her team are trying to prove.

Some hobbyists collect stamps; others probe the very heart of matter

(above) Richard Handl, whose name is sometimes transliterated as "Ray Palmer"

To each their own. Via the Washington Post:

 A Swedish man who was arrested after trying to split atoms in his kitchen said Wednesday he was only doing it as a hobby.

Richard Handl told The Associated Press that he had the radioactive elements radium, americium and uranium in his apartment in southern Sweden when police showed up and arrested him on charges of unauthorized possession of nuclear material.

…

Although he says police didn’t detect dangerous levels of radiation in his apartment, he now acknowledges the project wasn’t such a good idea.

“From now on, I will stick to the theory,” he said.

Usually, I find private experimentation that could potentially bring harm to unwitting bystandards reprehensible—hell, I don’t even like fireworks. But for some reason, I can’t help but admire Handl.

I’m brought to mind of Michio Kaku, the theoretical physicist who as a teenager built a functional particle accelerator in his parents’ garage. Both stood upon the shoulders of giants and reach to touch the world’s deepest core with their own hands, reaffirming the accessibility and practicality of knowledge we usually assume can only be uttered in the esoteric cloisters of the ivory tower.   

Which is not to say what Handl did was probably not incredibly reckless and deserving punishment. Yet I still hope Handl gets a light sentence and, before fading from the public consciousness, goes on to become a popularizer and demystifier of nuclear physics. As the industrial world burns off its fossil fuels, the much maligned specter of nuclear power could use a friendly public face.

After the Standard Model?

The Standard Model (SM) is the current best theory for the explanation of subatomic particles. It yeilds some of the most accurate and precise predictions of any mathematical-physical theory, but is still problematic and incomplete.  Apparently, to those whose eyes are trained to recognize mathematical aesthetics, the SM’s equations are contrived and fugly, whereas most great physics equations are elegant in their simplicity. (Apparently.) But more importantly, SM has yet to be reconciled to Einstein’s relativity, and it says nothing about dark matter, a.k.a. “the stuff that constitutes a full quarter of all the stuff in the observable universe.” Kind of a big oversight.  

So despite its wild predictive powers, many physicists (especially those given to the flights of sensationalism necessary for commercial success in popular science books) have always thought of the SM as a temporary scaffold utilized in the construction of a grander theory with firmer and broader foundations.

So it’s understandable that some people are getting very excited about a recent experiment conducted at Illinois’ Fermilab that seems to contradict the SM, which could clear space for a more complete theory of fields and particles.  Via Ron Cowen at Science News:

For the second time in weeks, the relatively small Tevatron at the Fermi National Accelerator Laboratory in Batavia, Ill., has found evidence of a possible new particle that would govern a new force in nature.The latest finding, reported online April 6 at arXiv.org (arxiv.org/abs/1104.0699), is based on an unexpected excess in jets of particles produced at the accelerator.

A new particle similar to but heavier than the W boson and Z boson would explain the observed excess. W and Z bosons are fundamental particles that transmit the weak force, which is responsible for radioactive decay.

Less likely, says Fermilab theorist Dan Hooper, is the possibility that the new particle is a version of the long-sought Higgs boson. This version of the Higgs would be heavier than the one predicted by physicists’ standard model of particles and forces, and it would interact less often with matter. Considered the last missing piece of the standard model, the elusive Higgs boson was conceived of as a way to explain why some elementary particles have masses.

However, let’s not get ahead of ourselves. Experts are, as they should be, cautious:

On the other hand, explaining the data may not require a new particle or a new force. The excess may have arisen from some aspect of ordinary particle interactions that researchers don’t understand, says Hooper, who was not involved in the new work.

The evidence is based on studies at the CDF experiment, one of two projects at the Tevatron, which collides a beam of protons with antiprotons moving at energies of nearly 1 trillion electron volts. In the new analysis, Titta Aaltonen of the University of Helsinki and a long list of collaborators homed in on collisions between 2001 and 2009 that produced a W boson along with two lightweight jets of particles, including electrons. Jets are relatively common and are a sign of quarks, which can’t be seen directly, but which fragment into other particles. The production of such jets in conjunction with the W boson is an essential starting point in probing physics beyond the standard model, Aaltonen and his colleagues note.

Looking at collision products at energies between 120 billion and 160 billion electron volts, the physicists saw an unexpected peak: They found about 250 more such events than predicted by the standard model.

There’s only a 0.076 percent chance that the excess is a fluke, the team notes in the paper. Though small, that percentage isn’t small enough to meet the standard criteria for proof in physics. In comparison, another unexpected recent finding at the Tevatron’s CDF, which also hints at a new elementary particle, has a smaller chance — 0.04 percent — of being wrong. But even that does not meet the standards of proof generally accepted in the field. CDF spokesperson Rob Roser of Fermilab does say, however, that the earlier finding “has a better chance of standing the test of time” than the excess jets result reported April 6.

Still, the jet excess captivates several theorists, including Hooper, because of the potential to actually find a new particle at the Tevatron and determine the particle’s mass. Visually, the peak energy of the excess, at about 145 billion electron volts, “jumps out at you,” indicating the mass of a possible new elementary particle, Hooper notes.

Time will tell.

NZ physicists mathematically describe quantum entanglement in time

A time-lapsed photo of moths around a lamp, by Steve Irvine. I like to think of it as an illustration of the "temporal parts" of objects four-dimensional theories of time predict.

Via PhysOrg:

In “ordinary” quantum entanglement, two particles possess properties that are inherently linked with each other, even though the particles may be spatially separated by a large distance. Now, physicists S. Jay Olson and Timothy C. Ralph from the University of Queensland have shown that it’s possible to create entanglement between regions of spacetime that are separated in time but not in space, and then to convert the timelike entanglement into normal spacelike entanglement. They also discuss the possibility of using this timelike entanglement from the quantum vacuum for a process they call “teleportation in time.”

“To me, the exciting aspect of this result (that entanglement exists between the future and past) is that it is quite a general property of nature and opens the door to new creativity, since we know that entanglement can be viewed as a resource for quantum technology,” Olson told PhysOrg.com. “The greatest significance of our result is almost certainly in some application that is yet to be imagined.”

Olson and Ralph’s paper, which is posted at arXiv.org, describes how timelike entanglement can be converted into spacelike entanglement using two detectors.

“Essentially, a detector in the past is able to ‘capture’ some information on the state of the quantum field in the past, and carry it forward in time to the future — this is information that would ordinarily escape to a distant region of spacetime at the speed of light,” Olson said. “When another detector then captures information on the state of the field in the future at the same spatial location, the two detectors can then be compared side-by-side to see if their state has become entangled in the usual sense that people are familiar with — and we find that indeed they should be entangled. This process thus takes a seemingly exotic, new concept (timelike entanglement in the field) and converts it into a familiar one (standard entanglement of two detectors at a given time in the future).”

In their study, the scientists also proposed a thought experiment in which they move a quantum state into the future using timelike entanglement as the resource. They call the process “teleportation in time.”

In the thought experiment, the physicists described two qubit detectors, one of which is coupled to the field in the past and one to the field in the future. First, the detector coupled to the past operates on a qubit and generates information about how the qubit can be detected. The qubit is then teleported into the future, essentially skipping over a middle period of time. Then the first detector is removed and the second, future-coupled detector is placed in the first detector’s spatial location, so that the detectors are separated in time but not in space. After a certain amount of time, the second detector receives the information from the first detector, which it uses to reconstruct the teleported qubit.

The physicists emphasized that there is an important symmetric time correlation that must be followed in order for the procedure to work. If the qubit is teleported at t=0, then the first detector must have operated the same amount of time before t=0 as the second detector operated after t=0. For example, if t=0 is 12:00, and the first detector operated at 11:45, then the second detector must wait to operate at exactly 12:15 in order to achieve entanglement. The scientists also noted that between 12:00 and 12:15, it’s impossible to recover the teleported qubit.

According to the physicists’ previous work, such timelike entanglement should generate a new thermal effect arising from the quantum vacuum (the quantum vacuum is thought to exhibit several thermal effects, including Hawking radiation from black holes, though none of these thermal effects have been observed). The physicists predict that the new thermal effect may be easier to observe than other thermal effects using current technology. If such a procedure for extracting and converting timelike entanglement can be realized, then it could provide a way for scientists to directly observe the quantum entanglement inherent in the space-time vacuum for the first time.

“Entanglement is observed every day,” Olson said. “However, direct observation of entanglement in the vacuum state would be new, and being able to observe it would potentially enable us to use this entanglement as a resource for quantum technology. Since the vacuum state is the closest thing we have to ‘nothing’ in physics (it is the state with zero ordinary particles around), observing and using the entanglement inherent in the vacuum as a technological resource would potentially give us a way to build quantum devices with just empty space as the most fundamental ingredient.”

In a Wired interview,  physicist Jorma Louko and science writer Lisa Grossman speculate on possible experimental verifications of the hypothesis–however, they would have to be conducted near a black hole or on a spaceship traveling near the speed of light. Both these venues are beyond our species the foreseeable future. For now, it looks like the success of the timelike entanglement hypothesis will depend on the success of its mathematics, and further study of vanilla spacelike entanglement.

But that’s not the only reason we shouldn’t be too hasty about the conclusions. I’m ignorant of the protocols of the physics community, but it is always suspicious when an academic paper receives its first publicity in the popular press instead of a journal. Most journalists are ignorant of the peer-review processes of the sciences, so some will credulously pass along the claims a scientist tells them, if its done in authoritative-sounding tones. The wild speculations of scientists in front of the popular press is how the rumors about the Large Hadron Doomsday Device and time-traveling saboteur bosons got started.

Which isn’t to say I don’t trust Olson; I’m just saying skepticism is a warrented and indeed virtuous stance to assume when approaching scientific claims, especially radical ones.

But let’s, for the sake of speculation, let’s assume the paper is correct. If timelike entanglement is an actual phenomena, the “practical” technological potential of the hypothesis, however intriguing it may be, is less interesting to me than its potential philosophical implications.

Now, for my next remark, I have to warn that I’m speculating in a field I’m not formally educated in: But if timelike entanglement holds up, it would seem to provide evidence for the truth of the four dimensionalist theory of time, which maintains the past, present and future all have an equal claim on reality.

For if quantum entities A and B are connected by timeline entanglement, they are able to effect each other, even though at any given moment on the timeline only one would be in the entangled state. That sounds like garbled self-contradiction, but might only be a paradox.

Though on the macroscopic scale causality can only exert itself locally–one billiard ball has to actually strike another to move it–at the quantum level, entangled particles don’t have to be touching to effect each other. Likewise, on the human scale causation is bound in time so that it can only move ”forward” in a linear fashion. But if Olson is right, information shared between entangled entities can bypass the intervening time between them. But this implies that both points in time must be ontological equals.

But again, I’m guessing here. I might have misunderstood what Olson is describing, or missed an important step in my logic.

But it would be ironic, if quantum physics were to supply another datum of evidence for a position formulated from the facts of special relativity.