Thinking About Time Travel Helps Solve Problems in Physics

Physicists have shown that simulating models of hypothetical time travel can solve experimental problems that appear impossible to solve using standard physics. Credit: Yaroslav Kushta via Getty Images

Time travel. We’ve all thought about it at one time or another, and the subject has been explored extensively in science fiction. Once in a while, it is even the subject of scientific research, typically involving quantum mechanics and how the Universe’s four fundamental forces (electromagnetism, weak and strong nuclear forces, and gravity) fit together. In a recent experiment, researchers at the University of Cambridge showed that by manipulating quantum entanglements, they could simulate what could happen if the flow of time were reversed.

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Do Advanced Civilizations use Black Holes as Giant Quantum Computers?

Artist view of an active supermassive black hole. Credit: ESO/L. Calçada

If life is common in our Universe, and we have every reason to suspect it is, why do we not see evidence of it everywhere? This is the essence of the Fermi Paradox, a question that has plagued astronomers and cosmologists almost since the birth of modern astronomy. It is also the reasoning behind the Hart-TIpler Conjecture, one of the many (many!) proposed resolutions, which asserts that if advanced life had emerged in our galaxy sometime in the past, we would see signs of their activity everywhere we looked. Possible indications include self-replicating probes, megastructures, and other Type III-like activity.

On the other hand, several proposed resolutions challenge the notion that advanced life would operate on such massive scales. Others suggest that advanced extraterrestrial civilizations would be engaged in activities and locales that would make them less noticeable. In a recent study, a German-Georgian team of researchers proposed that advanced extraterrestrial civilizations (ETCs) could use black holes as quantum computers. This makes sense from a computing standpoint and offers an explanation for the apparent lack of activity we see when we look at the cosmos.

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Scientists Send Quantum Data Through a Simulated Wormhole

Simulated data wormhole
The wormhole created by researchers exists purely as data. (Illustration credit: Inqnet / A. Mueller / Caltech)

For the first time, scientists have created a quantum computing experiment for studying the dynamics of wormholes — that is, shortcuts through spacetime that could get around relativity’s cosmic speed limits.

Wormholes are traditionally the stuff of science fiction, ranging from Jodie Foster’s wild ride in “Contact” to the time-bending plot twists in “Interstellar.” But the researchers behind the experiment, reported in the Dec. 1 issue of the journal Nature, hope that their work will help physicists study the phenomenon for real.

“We found a quantum system that exhibits key properties of a gravitational wormhole, yet is sufficiently small to implement on today’s quantum hardware,” Caltech physicist Maria Spiropulu said in a news release. Spiropulu, the Nature paper’s senior author, is the principal investigator for a federally funded research program known as Quantum Communication Channels for Fundamental Physics.

Don’t pack your bags for Alpha Centauri just yet: This wormhole simulation is nothing more than a simulation, analogous to a computer-generated black hole or supernova. And physicists still don’t see any conditions under which a traversable wormhole could actually be created. Someone would have to create negative energy first.

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What’s Going on Inside a Black Hole? The Answers Could be Written on its Surface

Both quantum computing and machine learning have been touted as the next big computer revolution for a fair while now.  However, experts have pointed out that these techniques aren’t generalized tools – they will only be the great leap forward in computer power for very specialized algorithms, and even more rarely will they be able to work on the same problem.  One such example of where they might work together is modeling the answer to one of the thorniest problems in physics: how does General Relativity relate to the Standard Model?

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We Could Detect Alien Civilizations Through Their Interstellar Quantum Communication

The Parkes radio telescope at Parkes Observatory in New South Wales, Australia. Astronomers using the telescope detected what appeared to be a radio signal coming from the direction of Proxima Centauri in April and May 2019. Image via Daniel John Reardon/ Wikimedia Commons.

Since the mid-20th century, scientists have been looking for evidence of intelligent life beyond our Solar System. For much of that time, scientists who are engaged in the search for extraterrestrial intelligence (SETI) have relied on radio astronomy surveys to search for signs of technological activity (aka. “technosignatures“). With 4,375 exoplanets confirmed (and counting!) even greater efforts are expected to happen in the near future.

In anticipation of these efforts, researchers have been considering other possible technosignatures that we should be on the lookout for. According to Michael Hippke, a visiting scholar at the UC Berkeley SETI Research Center, the search should also be expanded to include quantum communication. In an age where quantum computing and related technologies are nearing fruition, it makes sense to look for signs of them elsewhere.

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Weekly Space Hangout – January 24, 2014: LEGO Mars Rover & the Supernova We Missed in the Star Party!

Host: Fraser Cain

Special Guests: Stephen Pakbaz, designer of the LEGO Mars Rover Kit, and Ray Sanders from CosmoQuest, who is unboxing and building the kit as we hang out!

Astrojournalists: Morgan Rehnberg, Sondy Springmann, Elizabeth Howell, Casey Dreier, David Dickinson, Nicole Gugliucci, Mike Simmons
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