Emptiness Tied in a Knot

O Time, thou must untangle this, not I;
It is too hard a knot for me t' untie. 

-Viola in Twelfth Night by William Shakespeare

The knot Viola speaks of in Twelfth Night is a complex love triangle. Knots are often used to symbolize complicated situations, in addition to anxiety and lasting commitments. Like Viola, when most of us think about knots our focus is on how tightly they are tied. For the scientists who study them however, knots are much more—they represent a unique approach to understanding the universe.

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Ask a Physicist: San Fran in Space

William, from Honolulu, wrote in this week to ask:

If there was a space station/city the size of San Francisco in geostationary orbit, what would it look like from ground level with the naked eye? Would it cast a noticeable shadow?

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Scientists Use Warped Light to Test Einstein’s Theory and Weigh Stars

When Einstein developed his general theory of relativity, commercial radio didn’t even exist yet. He could not possibly have imagined all of the fancy, high-tech equipment that scientists would use over the next 100 years to test—and verify—his predictions. In fact, he wasn’t even sure that all of his predictions could be tested experimentally because they resulted in such tiny, hard-to-measure effects.


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Blistering Planet Hotter Than Many Stars

Given its stats, the recently discovered planet KELT-9b probably deserves its own baseball card. The planet and its host star, KELT-9, compose a unique system among the exoplanets discovered so far. KELT-9 is a relatively young, very hot star and its scorching heat warms the near side of the planet to a blistering 7,800 degrees Fahrenheit. KELT-9b isn't just the hottest gas giant so far discovered, it’s hotter than many stars.

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LIGO for a 3-peat!

For the third time, a telltale signal of two colliding black holes has been caught by the dual detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO). Not only does the new detection reinforce LIGO’s capabilities and previous detections, it also provides clues about how these black hole systems form and just how common they are. In addition, each new detection is a chance to test the predictions of general relativity—predictions that can’t be tested in a lab.

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Where Sound Meets Flexible Electronics

Voice-securing your ATM card. Talking to your newspaper over coffee. Projecting your voice to a room full of people using only a thin, lightweight loudspeaker that fits in your pocket. With new research published last week in the journal Nature Communications, a team of scientists from Michigan State University and Georgia Institute of Technology has opened the door to these possibilities.


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Promising Results in Offworld Fertility Experiments

To the best of anyone’s knowledge, no one has had sex in space.

Only one married couple have been on the same mission, the Americans Mark Lee and Jan Davis, and according to NASA, nothing happened. There being no privacy in the space shuttle or the International Space Station, that is likely true.

But with NASA exploring ideas such as two-year voyages to Mars and eventual colonies on Mars and the moon, the question of reproductive safety is important, especially if humans wish to one day travel to the edges of the solar system and even beyond. Can space voyagers conceive healthy human babies?

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Focusing Sound with Metasurfaces: A New Way to Reduce Noise and Power Devices?

Whether it’s the neighbor’s barking dogs, pounding rain, the din of traffic, or the music of your own choosing, most of us are constantly surrounded by noise. Noise is energy, so that means most of us are constantly surrounded by a relatively safe, renewable, and clean form of energy. What if we could harvest this energy?

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Probing Quantum Behavior in a Large-Scale System

Quantum mechanics, it seems, is where physics breaks from making intuitive sense. In the realm of the infinitesimal, particles can be in two places at once, or display the "spooky" properties of entanglement. But it might not have to be that way—a few months ago, the good folks over at Veritasium put out a fantastic video drawing attention to an amazing phenomenon that was only recently discovered: a macroscopic, intuitively friendly system that behaves almost exactly like a quantum-mechanical one. Now, scientists are building on this work, discovering new properties of this system and linking them to their quantum-mechanical counterparts.

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Gravity Caught Stretching Quantum Objects

Black holes and quantum mechanics are two of the most intriguing physics topics. Their strange and exotic features certainty capture the imagination. Now, new research in the American Physical Society’s journal Physical Review Letters brings aspects of the two together in an experiment that shows, for the first time, that gravity stretches and squeezes quantum objects through tidal forces.

A macroscopic quantum state explores curved spacetime.
Image Credit: Peter Asenbaum.

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