A computer image of a Higgs interaction. By Lucas Taylor / CERN, CC BY-SA 3.0, Wikipedia Commons.
It sounds like a plot from a comic book or a sci-fi film, a theory that got a boost when one of the greatest discoveries in physics in the modern era, the discovery of the “God particle,”or the Higgs boson, the missing piece in the Standard Model of particle physics. In the preface to his book Starmus, Stephen Hawking warns that the Higgs Boson field could collapse, resulting in a chain reaction that would take in the whole universe with it.
Theoretical physicist Joseph Lykken says it would probably take billions of years before we reach that point. Lykken hails from the Fermi National Accelerator Laboratory in Batavia, Illinois. If it did happen though, you wouldn’t know it. One instant you are here, the next, you and everything else is swallowed up by an enormous vacuum bubble, traveling at light speed in every direction. Humanity would never see it coming.
Peter Higgs and colleagues first theorized the existence of the Higgs boson in 1964. The Large Hadron Collider (LHC) at CERN in Geneva, Switzerland finally discovered it in 2012. With this missing piece found, three of the four fundamental forces of nature become complete. The particle’s measured value is 126 billion electron volts. That’s 126 times a proton’s mass. This is just enough to maintain a state teetering near the edge of stability.
Everything in the universe contains a certain amount of energy. Even so, everything also adheres to the principle of stability. All substances want to become stable. To do that, one must contain as little energy as it can. When something has a high energy level, it is unstable, and moves to rid itself of excess energy, in order to achieve stability.
Part of the Large Hadron Collider (LHC) at CERN, where the Higgs boson was discovered.
Quantum fields imbue particles with various properties. They also want to move to a low energy state, here called a vacuum state. The Higgs Field may be the exception. It lends particles’ mass. Rather than being a vacuum, the Higgs Field contains potential energy it cannot rid itself of, making it a false vacuum and by nature unstable. This instability could spark off, if the field was able to absorb more energy. A certain point it could absorb no more, teeter over the brink and end everything in existence.
The Higgs Field is maintaining a low energy state at the moment. But some believe it is slowly transitioning to a high energy state. When it does, it will kick off what is known as “vacuum decay.” In Hawking’s book, once the Higgs Field becomes metastable, the vacuum decay bubble will emerge. Being at a high energy state, it will quickly move to consume everything at a low energy state, or everything else around it. The vacuum bubble moves along destroying atoms, turning everything it encounters into hydrogen.
Prof. Lykken believes it will take billions of years. “There's no principle that we know of that would put us right on the edge,” he said. University of Southern Denmark physicists strengthened the vacuum decay theory in a study published in the journal High Energy Physics. They found however that vacuum decay could occur at any moment.
Even so, there may be outside forces associated with the Higgs Field that influence it in unknown ways. Dark matter for example, that mysterious substance that could comprise up to 27% of the universe, may interact with the Higgs Field. Recently however, a team of prominent physicists brought into doubt whether or not dark matter actually exists. Another theory called “supersymmetry,” states that every particle has its opposite. This helps keep the universe stable. Could the Higgs boson have a twin? Would that particle keep it from vacuum decay? No one is sure.
A representation of the Higgs Field. by Gonis from es, CC BY-SA 3.0, Wikipedia Commons.
It is believed that when vacuum decay eventually takes place, what will be left is a superheated, hard, and extremely dense sphere. Some astrophysicists believe the universe, just before the Big Bang, may have looked like this. The Higgs Field is thought to have emerged shortly after the Big Bang. So it may be the driving force which deletes the universe and forces it to start over again.
This isn’t the only conceptualization which predicts the destruction of everything everywhere. Another is the Big Crunch theory. This is the opposite of the Big Bang. With the first, a collection of super dense material exploded, heaving everything out in all directions. With the Big Crunch, it’s thought that material eventually stops moving at some point, and begins traveling in the opposite direction, coming back together again.
So even if we are able to escape the planet and become an intergalactic species before the sun engulfs the earth, the universe itself may collapse. The only way to ensure longevity is if the multiverse actually exists, and we can become a multi-universal species. Whether it is the Big Crunch of Vacuum Decay that gets us, it’s interesting to think that perhaps after that dense, hot state, it could in theory explode again, causing a second Big Bang.
If true, how many times has the cycle occurred? And does history repeat itself exactly, or is a totally new universe born? It is of course important to remember that this is all in the realm of theoretical physics. The universe may hide as of yet a treasure trove of unknown particles which could change these predictions and speculations completely.
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Image source: carlos castilla/Shutterstock
- Quantum particles can tunnel through seemingly impassable barriers, popping up on the other side.
- Quantum tunneling is not a new discovery, but there's a lot that's unknown about it.
- By super-cooling rubidium particles, researchers use their spinning as a magnetic timer.
When it comes to weird behavior, there's nothing quite like the quantum world. On top of that world-class head scratcher entanglement, there's also quantum tunneling — the mysterious process in which particles somehow find their way through what should be impenetrable barriers.
Exactly why or even how quantum tunneling happens is unknown: Do particles just pop over to the other side instantaneously in the same way entangled particles interact? Or do they progressively tunnel through? Previous research has been conflicting.
That quantum tunneling occurs has not been a matter of debate since it was discovered in the 1920s. When IBM famously wrote their name on a nickel substrate using 35 xenon atoms, they used a scanning tunneling microscope to see what they were doing. And tunnel diodes are fast-switching semiconductors that derive their negative resistance from quantum tunneling.
Nonetheless, "Quantum tunneling is one of the most puzzling of quantum phenomena," says Aephraim Steinberg of the Quantum Information Science Program at Canadian Institute for Advanced Research in Toronto to Live Science. Speaking with Scientific American he explains, "It's as though the particle dug a tunnel under the hill and appeared on the other."
Steinberg is a co-author of a study just published in the journal Nature that presents a series of clever experiments that allowed researchers to measure the amount of time it takes tunneling particles to find their way through a barrier. "And it is fantastic that we're now able to actually study it in this way."
Frozen rubidium atoms
Image source: Viktoriia Debopre/Shutterstock/Big Think
One of the difficulties in ascertaining the time it takes for tunneling to occur is knowing precisely when it's begun and when it's finished. The authors of the new study solved this by devising a system based on particles' precession.
Subatomic particles all have magnetic qualities, and they spin, or "precess," like a top when they encounter an external magnetic field. With this in mind, the authors of the study decided to construct a barrier with a magnetic field, causing any particles passing through it to precess as they did so. They wouldn't precess before entering the field or after, so by observing and timing the duration of the particles' precession, the researchers could definitively identify the length of time it took them to tunnel through the barrier.
To construct their barrier, the scientists cooled about 8,000 rubidium atoms to a billionth of a degree above absolute zero. In this state, they form a Bose-Einstein condensate, AKA the fifth-known form of matter. When in this state, atoms slow down and can be clumped together rather than flying around independently at high speeds. (We've written before about a Bose-Einstein experiment in space.)
Using a laser, the researchers pusehd about 2,000 rubidium atoms together in a barrier about 1.3 micrometers thick, endowing it with a pseudo-magnetic field. Compared to a single rubidium atom, this is a very thick wall, comparable to a half a mile deep if you yourself were a foot thick.
With the wall prepared, a second laser nudged individual rubidium atoms toward it. Most of the atoms simply bounced off the barrier, but about 3% of them went right through as hoped. Precise measurement of their precession produced the result: It took them 0.61 milliseconds to get through.
Reactions to the study
Scientists not involved in the research find its results compelling.
"This is a beautiful experiment," according to Igor Litvinyuk of Griffith University in Australia. "Just to do it is a heroic effort." Drew Alton of Augustana University, in South Dakota tells Live Science, "The experiment is a breathtaking technical achievement."
What makes the researchers' results so exceptional is their unambiguity. Says Chad Orzel at Union College in New York, "Their experiment is ingeniously constructed to make it difficult to interpret as anything other than what they say." He calls the research, "one of the best examples you'll see of a thought experiment made real." Litvinyuk agrees: "I see no holes in this."
As for the researchers themselves, enhancements to their experimental apparatus are underway to help them learn more. "We're working on a new measurement where we make the barrier thicker," Steinberg said. In addition, there's also the interesting question of whether or not that 0.61-millisecond trip occurs at a steady rate: "It will be very interesting to see if the atoms' speed is constant or not."
