Science Corner: Back to the Present

You don’t need a DeLorean to see that this year is going to bring a lot of Back to the Future references and time travel talk. It’s fitting, then, that physicists have actually succeeded in constructing a quantum time machine. Well, sort of. (Isn’t that always the way with quantum physics?) It turns out, one can create subatomic systems under one set of conditions, and they will also behave as if they were under a different set of conditions. The first intuition is probably to imagine doing something slowly as a way to understand how it will work quickly, like a dancer or a martial artist practicing moves at quarter speed to get the motions right. But that’s not what I mean; it’s more like using slow and fast to simulate sweet and salty.

In this case, they are using two photons to simulate what it would be like for a single photon to interact with itself in the past. Since we don’t know if it’s actually possible for a photon to travel through time that way, it’s a pretty neat trick to do experiments with time travel anyway. And the good news is that their results match up with what we’d expect if the universe prevents grandfather paradoxes. In other words, if time travel is possible, it’s less like Back to the Future and more like 12 Monkeys or Primer. Probably more significant is that may provide the means to experiment at the intersection of quantum mechanics and relativity (without going into a black hole).

We often imagine time travel as a means to go back and fix things. But if you can’t change the past, what event would you go back to participate in exactly how it already happened?

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Andy Walsh

Andy has worn many hats in his life. He knows this is a dreadfully clichéd notion, but since it is also literally true he uses it anyway. Among his current metaphorical hats: husband of one wife, father of two elementary school students, reader of science fiction and science fact, enthusiast of contemporary symphonic music, and chief science officer. Previous metaphorical hats include: comp bio postdoc, molecular biology grad student, InterVarsity chapter president (that one came with a literal hat), music store clerk, house painter, and mosquito trapper. Among his more unique literal hats: British bobby, captain's hats (of varying levels of authenticity) of several specific vessels, a deerstalker from 221B Baker St, and a railroad engineer's cap. His monthly Science in Review is drawn from his weekly Science Corner posts -- Wednesdays, 8am (Eastern) on the Emerging Scholars Network Blog.

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2 Comments

  • Tom Grosh IV commented on February 4, 2015 Reply

    What a great question Andy! Personally I’m wrestling with whether I have the audacity to peek into a holy moment (tread on holy ground) such as the creation, the burning bush, the consuming of sacrificial fire in the face off between Elijah and the prophets of Baal, the Sermon on the Mount, the feeding of the 5000, the transfiguration, the Last Supper, the crucifixion, the resurrection, the ascension, Pentecost . . . Even as an observer, I have an uncomfortable sense of playing god with God.

    I think that I would be more comfortable observing a day in Mother Teresa’s ministry, the change of power in South Africa, the landing on the moon with the Apollo mission, Martin Luther King Jr’s delivery of “I have a dream,” a day in the life of Anne Frank and her family in hiding, the discovery of Penicillin, Marie Curie in the lab, Harriet Tubman in action, the first run of the difference engine, an intense moment of the French Revolution or the Reformation, Gutenberg’s first print job, Machu Picchu in its glory, Marco Polo’s travels, Genghis Khan’s leadership, Muhammed’s organizing abilities, Cleopatra’s political savvy, Caesar’s crossing of the Rubicon, Alexander the Great at the far reaches of his empire with Aristotle at his side, the 10 Commandments shared by Moses, the Buddha, Confucius, or Socrates teaching, the writing of the Code of Hammurabi, the first human discovery of Australia and the Americas, the first fire . . . the fall of the lost city of Atlantis ;)

    Ok. Time to stop before the list grows longer — I’ve started to think more of “Eureka!” moments in philosophy/writing.

    As for my final answer, at present I come back to the Last Supper, truly a table of hospitality, servanthood, and sacrifice . . . one which continues to extend to this day. If I were to take out Judeo-Christian events/moments — and had an unlimited amount of strength,skill, language proficiency when dropped into another context ;) — Marco Polo’s journeys top my list “at present.”

    How about about you? Do you have one to share ;)

    • drandrewwalsh@gmail.com'
      Andy Walsh commented on February 10, 2015 Reply

      Those are all great moments! In terms of Biblical history, I think I would choose to be among those that an adolescent Jesus taught in the temple, or perhaps among the Greeks at the Areopagus when Paul came to visit. Expanding the scope, I might see what it was like to attend the premiere of Hamlet or Beethoven’s Ninth Symphony, something along those lines. I’ve always been curious what the experience of arts performance was like in earlier eras, and how works we currently think of as masterpieces were received initially.

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