Imagine if matter could go through other matter. Wouldnt the world be a different place?

Lets say you went on a hiking trip and arrived at a bridge over a river. Theoretically, you have two options to get to the other side: you could either go over the bridge, or you could paddle under it. But what if you could go through the bridge?

This is analogous to a phenomenon in quantum physics physics at very small length scales known as quantum tunnelling. A recent Nature publication highlights a discovery made on quantum tunnelling by Dr. Aephraim Steinberg and his team at the University of Torontos Department of Physics.

The team proved that quantum tunnelling is not instantaneous. In other words, if a particle were to go through a barrier, it would spend a certain amount of time in the barrier. According to Steinberg, the most surprising thing about the principle of quantum tunnelling is that a particle going through a barrier need not be an electron.

In principle, a baseball could do this, he said in an interview with The Varsity.

What is quantum tunnelling?

Most physicists explain quantum tunnelling with a classic analogy of a ball and a hill. If you try to push a ball up a hill and you give it a strong push, it wont get over the crest of the hill unless you give it one big push so that it can reach the hilltop. In physics talk, you need to make sure that the ball has enough kinetic energy to overcome the hills potential energy.

However, the quantum world doesnt use those seemingly logical rules and it is for this reason that the field of quantum mechanics can be so difficult to explain.

Unlike classical physics, quantum physics is probabilistic. That means that instead of calculating the exact locations and positions of particles, quantum physicists investigate the probability of electrons being located in a certain area.

If you had a quantum ball and hill scenario, even though it is highly likely that youll find the ball on your side of the hill, theres still a tiny probability that youll find your ball inside the hill. Theres an even smaller chance that your ball could eventually end up on the other side of the hill almost as if it had dug a tunnel through.

This is how quantum tunnelling is observed in most experiments: a change in location from one side of a barrier to another.

According to Steinberg, he wouldnt call his recent findings a discovery.

I think very few people thought the process was instantaneous, he said. Theres been over 80 years of debate over how exactly one should talk about the duration and process of different attempts to define and to measure it. And a year or two ago, there was a new story with another group, and they found that it was instantaneous. And we disagreed with that description.

How did Steinbergs team do it?

The team measured how long a rubidium atom spends inside a barrier of light constructed using lasers and microwaves. Rubidium atoms were cooled to one nanokelvin and directed by lasers to move in one direction. The path of these atoms was then blocked by another laser beam, which served as a barrier of light. The experimenters wanted to know how long the atoms spent inside the barrier before making it out on the other side.

So, how do you measure the travel time of an atom?

If you let every particle carry its own stopwatch, and then you wait and look through to see when the particle appears on the other side, you can look at its stopwatch [to measure the time it took], Steinberg said. It turns out that particles like electrons and atoms have a property called spin and the spins react to magnetic fields.

Steinberg and his colleagues used the spins of the rubidium atoms as hands on a clock face. Inside the light barrier, they exposed the atoms to a magnetic field, which caused the clock hands to rotate effectively revealing how long each atom spent inside. The longer the particle took inside the barrier, the longer it was exposed to the magnetic field, and the more its spin rotated.

Ultimately, the researchers found that each atom spends 0.61 milliseconds inside the light barrier a small number, but definitely not zero.

Basically, what were really striving for is simply a better understanding of how the quantum mechanical particles get where they get, Steinberg said. Tunnelling is one of the most striking examples of this. Honestly, what interests me is the modern question of how we think about this quantum world at all.

Quantum tunnelling is a process we see in our everyday lives.

[It has a role in] things like photosynthesis, even vision, where electrons and even protons are required in order to transfer energy along some of the biochemical pathways, Steinberg said. And maybe one of the most fundamental [roles quantum tunnelling has] in our existence is that a lot of nuclear processes require tunnelling. So the fusion that occurs in the sun that allows us to survive actually relies on tunnelling as well.

Whats next for the team?

Steinberg noted that his team is going in a few different directions.

Its relatively straightforward to just calculate if I throw a lot of particles in a barrier on average, how much time [they would spend] in the barrier. Thats not so difficult, Steinberg said. What makes the process confusing comes back to this indeterminism in quantum mechanics; some particles get through and others are reflected. People wanted to know, How long does it take just for the particles to get through?

But the team was in for a surprise. In the particular place they looked, transmitted and reflected particles spent the same amount of time in the barrier. Steinberg is now interested in asking different questions.

Instead of just asking, How much time do the particles spend overall in the barrier? you ask more specific questions. Where in the barrier are they spending most of their time? Are they on the left hand side or on the right hand side or middle? Steinberg said. Then, we expect to actually see different results with the transmitted and the reflected particles. So we want to refine our experiments to do that.

The probabilistic and often controversial nature of quantum physics has given the physicist a lot to think about.

Although the predictions for what were used to asking are probabilistic, the laws that we use for our predictions are, in fact, completely deterministic, Steinberg said. In other words, we can predict exactly what the final probability distribution is theres no ambiguity about that.

Steinberg continued, So its a controversy thats more on the philosophical side. What does it mean to have a description of nature that only gives us probabilities? And does it give us definite results?

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U of T physicists discover that quantum tunnelling is not instantaneous - Varsity

Albert Einstein's work so revolutionized physics that it is difficult to discusshim without slipping into hagiography. Indeed, his brilliance is so storied thathis surname has become synonymous with "genius," and his brain preserved for study.

And yet, while Einstein was undeniably a smart cookie, one cannot look back at the course of history without noticing that the dominoes were all there, set up, and waiting for someone like him to start toppling them. Part of Einstein's brilliance was merelyrealizing this. Avi Loeb, a professor of physics at Harvard University with a regular a column in Scientific American, told me that he thinks that Einstein's physics revelations would have been developed by others even if Einstein hadn't been born. "It would take maybea few more decades," Loeb clarified."Many of the things that Einstein personally was responsible for there at least 10 touchstonesin physics where each of them is a major intellectual achievement you know, they would be discovered by different people, I think," Loeb continued. "That illustrates his genius."

Loeb is advising on a publicproject celebrating Einstein's life and work at Hebrew University, which hosts an archive of Einstein's documents. The project,"Einstein: Visualize the Impossible," is slated to be an interactive online exhibition to engage the public with Einstein's work. As a fellow physicist, Einstein's work and hislife haveweighed on Loeb's mind for years, which is why he was interested in helping curate.

In considering Einstein's legacy, though, Loeb says we have to reckon with what has and hasn't changed about the physics world. In the 1890s, when Einstein was in college, physics knowledge was a shell of what it istoday. Quantum mechanics, dark matter, nuclear physics and most fundamental particles wereunknown, and astronomers knew little about the nature of the universe or even that there were other galaxies outside our own. Nowadays, many of the biggest physics discoveries happen by virtue of some of the largest and most expensive scientific instruments ever built: gravitational wave observatories, say, or the Large Hadron Collider at CERN.

Given the landscape of physics today,could an Einstein-like physicist exist again someone who, say,works in a patent office, quietly ponderingthe nature of space-time, yet whose revelations cause much of the field to be completely rethought?

Loeb thought so. "There are some dark clouds in physics," Loeb told me. "People will tell you, 'we just need to figure out which particles makes the dark matter, it's just another particle. It has some weak interaction, and that's pretty much it.' ButI thinkthere is a very good chance that we are missing some very importantingredients that a brilliant person might recognize in the coming years." Loeb even said the potential for a revolutionary physics breakthrough today "is not smaller it's actually bigger right now" than it was in Einstein's time.

I spoke with Loeb via phone about Einstein's legacy, and how physics has become "stuck" on certain problems; as always, this interview has been condensed and edited for print.

To start, let's talk about some of Einstein's contributions to science. What compelled you to help curate this celebration of Einstein's legacy?

Well, to start, Einstein's special theory of relativityrevolutionized our notion of space and time. The fact thatspace and time are entities that are lumped together and that the speed of light is the ultimate speed, and, and that you can convert mass to energy, which is demonstrated bynuclear energy in particular. Then later on, he made the extremely important contributions to quantum mechanics, andof course developed the general theory of relativity that he published in November 1915, 105 years ago. And amazingly,exactly a hundred years later, in August, 2015,gravitational waves were detected by the LIGO experiment and they demonstrated that not only do gravitational waves exist, which are ripples in space and time that Einstein's theory forecasted, but also thatthe forces of these gravitational waves are black holes, which are also a prediction of Einstein's theory.

Obviously Einstein was very visionary, but also in a sense, he had peers people like Karl Schwarzchild and Edwin Hubble who were doing work that wouldhelp him test and correlate his theories. I've wondered, say, if Einstein were born 30 years later, would someone else havefigured out relativity, andthe photoelectric effect, and so on?

That's a good question. Physics is about nature, right? So we're trying to learn about nature. We're trying to understand nature and you know, so, in that sense, wecollect data and eventually someone comesup with the right idea. The question is, how long does thattake?What I'm saying is,I believe that the same ideas would have been developed. I don't know how close to the time that Einstein and thought about them, but eventually. . . .it would take maybe a few more decades or something. Butthe most important thing is, I think it would have been fragmented. So, you know, many of the things that Einstein personally was responsible for like there at least 10 touchstones in physics where each of them is a major intellectual achievement they would be discovered by different people. So the fact that he came up with with all of them illustrates his genius.

But you know, if you look at people that got the Nobel prize, there are many people examples of people that got it once for one major discovery, that's pretty much what they did for their life. Either they did it early on in their life or late, but doesn't matter. And that's not true about Einstein. So he didn't only deviatefrom the beaten path and, and come up with original ideas, but he did it multiple times. And by that, you know, it contributed to humanity. A great deal, I should say, like for example, hisa general theory of relativity this idea that space and time and gravity are connected.

It seems like physics has changed between Einstein's day and now. Most of the underlying physical principles of our universe appear to have been well-defined and tested by now say, the standard model of particle physics, or relativity and gravitation. And a lot of advances happen now because of data from huge teams working on government-funded instruments. Given thelandscape of physics, is it actually possible that there could be somebody else like Einstein nowadays, someone who revolutionizes the whole field?Or do you think things have sort of fundamentally changed both in terms of funding of experimentsand of our understanding of the universe so that such a thing isno longerpossible?

I mean, we do have much bigger experiments as you said, and much more data in some fields. But we still need people that think about the blueprint of physics, thatthink about the fundamental assumptions that everyone else is making that might be wrong. We need critical thinking. And there are some dark clouds on the horizon, just as they were 150 years ago. You know, back then, back then it was the blackbody radiation. And people at the time thought, "well, we just need to clarifythat dark cloud, and then we finish physics." [Editor's note: in the 1890s, the fact that objects glowed different colors as they heated up was one of the great mysteries of physics. It turned out to be related to quantum mechanics, the study of which prompted an ongoing revolution in physics.]

And right now there are some dark clouds, too, you know. Like, there is the nature of dark matter, orthe nature of the cosmological constant, or that we don't know where the vacuum gets its energy from. People will tell you, "oh, these are just minute details. You know, we just need to figure out which particles makes the dark matter, it's just another particle. It has some weak interaction, and that's pretty much it. And the dark energy, you know, it's just the vacuum energy density, you know, for some reason it's more maybe, because otherwise we wouldn't exist here." You know, we can give each other awards and celebrate the end of physics.

I think it'spretty much similar [to the 19th century situation]. And I think there, there is a very good chance that we are missing some very importantingredients that a brilliant person might recognize in the coming years,in the coming decades.

What are some of the "dark clouds" in physics,as you say?

One of thechallenges is unifying quantum mechanics and gravity. So you have this huge contingency of string theories that agree among themselves that they are leading the frontier, but nevertheless, they haven't provided any concrete predictions that can be tested by experiments over the past 40 years. [Editor's note: String theory unifies quantum mechanics and gravity, but it is, as Loeb mentions, not testable as far as anyone knows.]

[String theorists]are still advocating that they're the smartest physicists although they're not doing physics, because in my book, physics is about testing your ideas against reality, with experiments. And, you know, I very much believe thatput your theory to the guillotine of experimental data, and it may cut its head off. But if you don't risk your theory by testing it, you can be very proud of yourself.The only way that you maintain your humility is by recognizing that there is something superior to your ideas, which is nature. And it's a learning experience where you're not supposed to know everything in advance.

And that's unfortunately not popular these days. Today, it's all about impressing each other. And that's part of social media, you know, trying to impress other people to say things that look smart, that look very intelligent, thatcompletely alignwith what everyone else is saying so that they will like you, that you would have more likes on Twitter. Okay. So that's the motivation, so that you can get more awards, more grants so that you can get a tenure appointment and everyone would respect you.

That's wrong. That was clearly not the motivation of Einstein. He was not trying to be liked, and that's why he wasworking in a patent office. But hisideas happened to be right. And in a way he was naive in that sense, but that's the right approach you should be always learning.

So I would say there is the same potential even greater now because we are at a time when we recognize the success of physics. It has a huge impact on the economy, on politics, and so forth. So we recognize that but if you look at the frontiers of physics, which is blue sky research, you know, it's supposed to be open minded butit's not open-minded. Thereare groups of people, entrenched in ideas that will never be tested and they believe that they're leading the frontier.

Right. So are you saying that the premise of the some of the major experiments might even be wrong? Like, all the prominent dark matter experiments are trying to find this weakly-interacting, supersymmetric particle, but even that assumption may be wrong?

So here is an example:Supersymmetry, you know, that was an idea advocated for decades now. [Editor's note: Supersymmetry is the theory that for every fundamental particle, there is a "partner" particle; so for the electron, there would be a supersymmetric "selectron," and for the top quark, there would be a supersymmetric "squark," and so on. Dark matter is theorized to be made of one of these particles. Yet none of the supersymmetric particles have ever been observed.]And people celebratedthis idea, and gave each other awards. The Large Hadron Collider in CERN was supposed to detect the lightest supersymmetric particles and it didn't. There'sno evidence for supersymmetry.

So obviously what people say is, "oh, maybe it's around the corner." But it's already ruled out the most natural versions of supersymmetry are ruled out. So here's an idea that was celebrated as part of the mainstream not only celebrated, but it was the foundation for string theory.So they put it as a building block:"We know it exists, put it as a brick at the bottom of the tower that we are building called string theory, called superstring theory. And let's assume that we know it it's completely trivial,experimentalists willeventually find it, we don't even need to think about it let's put it as a building block of our tower."

Doesn't exist. LHD [Large Hadron Collider]didn't find it. So then, people say, "okay, weakly interactingmassive particles are dark matter butfor decades, they haven't found anything. [Editor's note: One prominent theory to explain dark matter is that it consists of particles that are heavy but rarely interact with normal matter, though they bounce off of themselves and have a gravitational interaction. Most of the major experiments searching for dark matter are attempting to find this type of weakly interacting massive particle, or WIMP for short.]

And so I asked the experimentalists, "how long will you continue to search for WIMPs, these weakly interacting particles, since the limits are orders of magnitude below the expectation?" And he said, "I will continue to search for WIMPs as long as I get funding."

So in the mainstream approach, there is thisstubbornness like, we stick to the ideas that we believe in. And then anyone that deviates from that will besidelined. You know, anyone that considers any other theory for unifyingquantum mechanics and gravity through string theory is sidelined,even though there is no reasonable evidence for string theory. So I would say the potential now for a breakthrough that will be really revolutionary is not smaller it's actually bigger right now [than it was in Einstein's]. It's just, the social pressure is stronger.

Sowe do need we desperately need another Einstein. There is no doubt.

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Physics is stuck and needs another Einstein to revolutionize it, physicist Avi Loeb says - Salon

Written by AZoQuantumSep 8 2020

At the University of Tsukuba, a researcher has come up with a new explanation for how superconductors subjected to a magnetic field can returnwithout losing any energyto their earlier state once the field is removed.

This study could pave the way for a new theory of superconductivity and a more environment-friendly electrical distribution system.

Superconductors are a family of materials that exhibit the remarkable ability to conduct electricity without any resistance. As such, an electrical current can indefinitely circle around a loop of superconducting wire. The obstacle is that it is necessary to maintain these materials very cold, and more so, a strong magnetic field can make a superconductor to recover back to normal.

Previously, it was considered that it is not easy to reverse the transition from being superconducting to normal induced by a magnetic field. This is because the energy would be dissipated by the typical process of Joule heating.

This mechanism, where the electrical energy is converted into heat by the resistance in normal wires, is precisely what enables the use of an electric stovetop or space heater.

Joule heating is usually considered negatively, because it wastes energy and can even cause overloaded wires to melt. However, it has been known for a long time from experiments that, if you remove the magnetic field, a current-carrying superconductor can, in fact, be returned to its previous state without loss of energy.

Hiroyasu Koizumi, Professor, Division of Quantum Condensed Matter Physics, Center for Computational Sciences, University of Tsukuba

Professor Koizumi has now offered a new explanation for this phenomenon. Although the electrons couple up and move synchronously in the superconducting state, the actual reason behind such a synchronized motion is the existence of the so-called Berry connection, which is characterized by the topological quantum number.

This number is an integer and if it is a nonzero number, then there is a flow of current. Consequently, this supercurrent can be abruptly turned off by modifying this number to zero in the absence of Joule heating.

Previously, James Clerk Maxwell, the founder of modern electromagnetic theory, hypothesized a similar molecular vortex model that visualized space being filled with the rotation of currents in small circles. As everything was spinning in the same manner, it reminded Maxwell of idle wheelsgears used in machines for this purpose.

The surprising thing is that a model from the early days of electromagnetism, like Maxwells idle wheels, can help us resolve questions arising today. This research may help lead to a future in which energy can be delivered from power plants to homes with perfect efficiency.

Hiroyasu Koizumi, Professor, Division of Quantum Condensed Matter Physics, Center for Computational Sciences, University of Tsukuba

Koizumi, H. (2020) Reversible superconducting-normal phase transition in a magnetic field and the existence of topologically protected loop currents that appear and disappear without Joule heating. EPL. doi.org/10.1209/0295-5075/131/37001.

Source: http://www.tsukuba.ac.jp/en

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Mechanism Proposed to Explain Resilience of Superconductors to Magnetic Fields - AZoQuantum

Can you already hear Morgan Freemans sonorous voice as if this was another episode of Through the Wormhole?

Astrophysicists have figured out a way to traverse a (hypothetical) wormhole that defies the usual thinking that wormholes (if they exist) would either take longer to get through than the rest of space or be microscopic. These wormholes just have to warp the rules of physics which is totally fine since they would exist in the realm of quantum physics. Freaky things could happen when you go quantum. If wormholes do exist, some of them might be large enough for a spacecraft to not only fit through, but get from this part of the universe to wherever else in the universe in one piece.

"Larger wormholes are possible with aspecial type of dark sector,a type of matter that interactsonly gravitationally with our own matter. The usual dark matter is an example.However, the one we assumed involves a dark sector that consists of an extradimensional geometry,"Princeton astrophysicist Juan Maldacena and grad student Alexey Milekhin told SYFY WIRE.Theyrecently performed a new study that reads like a scientific dissection of what exactly happened to John Crichtons spaceship when it zoomed through a wormhole in Farscape.

"This type of larger wormhole isbased on therealization that a five-dimensional spacetime could be describing physics at lowerenergies than the ones we usually explore, but that it would have escaped detection because it couples with our matter only through gravity," Maldacena and Milekhinsaid."In fact, its physics issimilar to adding many strongly interacting massless fields to the known physics,and for this reason it can give rise to the required negative energy."

While the existence of wormholes has never been proven, you could defend theories that they could exist deep in the quantum realm. The problem is, even if they do exist, they are thought to be infinitesimal. Hypothetical wormholes would also take so long to get across that youd basically be a space fossil by the time you got to the other end. Maldacena and Milekhin have found a theoretical way for a wormhole thatcould get you across the universe in seconds and manage not to crush your spacecraft. At least it would seem like seconds to you. To everyone else on Earth, it could be ten thousand years. Scary thought.

"Usually whenpeople discuss wormholes, they have in mind 'short'wormholes: the ones forwhich the travel time would be almost instantaneous even for a distant observer.We think that such wormholes are inconsistent with the basic principles of relativity," the scientists said. "The ones we considered are 'long': for a distant observed the path alongnormal space-time is shorter than through the wormhole.There is a time-dilation factor because the extreme gravity makes travel time very short for the traveller. For an outsider, the time it takes is much longer, so we have consistency with the principles of relativity, which forbid travel faster than the speed of light."

Fortraversable wormholesto exist, but the vacuum of space would have to be cold and flat to actually allow for what they theorize. Space is already cold. Just pretend that its flat for the sake of imagining Maldacena and Milekhin's brainchild of a wormhole.

"These wormholes are big, the gravitational forces will be rather small. So, if they were in empty flat space,they would not be hazardous. We chose their size to be big enough so that theywould be safe from large gravitational forces," they said.

Negative energy would also have to exist in a traversable wormhole. Physics forbids such a thing from being a reality. In quantum physics, the concept of this exotic energy is explained by Stephen Hawking as the absence of energy from two pieces of matter being closer together as opposed to being far apart, because energy needs to be burned so they can be separated despite gravitational force struggling to pull them back together. Fermions, which include subatomic particles such as electrons, protons, and neutrons (with the exception that they would need to be massless), would enter one end and travel in circles. They would come out exactly where they went in, which suggests that the modification of energy in the vacuum can make it negative.

"Early theorized wormholes were not traversable; an observer going through a wormhole encounters a singularity before reaching the toher side, which is related ot the fact that positive energy tends to attract matter and light," the scientists said."This is whyspacetime shrinks at the singularity of a black hole. Negative energy prevents this. The main problem is that the particular type of negative energy that is needed is not possible in classical physics, and in quantum physics it is only possible in some limited amounts and for special circumstances.

Say you make it to a gaping wormhole ready to take you...nobody knows where. What would it feel like to travel through it? Probably not unlike Space Mountain, if you ask Maldacena and Milekhin. In their study, they described these wormholes as "the ultimate roller coaster."

The only thing a spaceship pilot would need to do, unlike Farscapes Crichton, who totally lost control, is get the ship in sync with the tidal forces of the wormhole so they could be in the right position to take off. These are the forces that will push and pull an object away from another object depending on the difference in the objects strength of gravity, and that gravity would power the spaceship through.This is whyit would basically end upflying itself. But there are still obstacles.

"The problem is that every object which enters the wormhole will be acceleratedto very high energies," the scientists said."It means that a wormhole must be kept extremely cleanto be safe for human travel. In particular, even the pervasive cosmic microwaveradiation, which has very low energy, would be boosted to high energies andbecome dangerous for the wormhole traveler."

So maybe this will never happen. Wormholes may never actually be proven to exist. Even if they dont, it's wild to think about the way quantum physics could even allow for a wormhole that you could coast right through.

Continued here:

If you flew your spaceship through a wormhole, could you make it out alive? Maybe... - SYFY WIRE