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Category: physics – Page 139

Backwards through time? We travel forwards every day, but traveling back could let us change our past, visit old friends, or manipulate the timeline to our benefit… Although our knowledge of space and time remains incomplete, we can still use what we know to consider possible time machines. But what kind of paradoxes would this entail and how can we resolve them? Join us today on a special journey through time.

An educational video written and presented by Professor David Kipping.

This video is based on research conducted at the Cool Worlds Lab at Columbia University, New York. You can now support our research program directly here: https://www.coolworldslab.com/support.

All music used is licensed by SoundStripe.com or through Creative Commons:
► “It’s Always Darkest Before the Dawn” by Hill, licensed through SoundStripe.com: https://app.soundstripe.com/songs/7441
► “Waking Up” by Atlas, licensed through SoundStripe.com: https://app.soundstripe.com/songs/3984
► Cylinder Four (http://chriszabriskie.com/cylinders/) by Chris Zabriskie (http://chriszabriskie.com/); licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/)
► “Always Dreaming” by Caleb Etheridge, licensed through SoundStripe.com: https://app.soundstripe.com/songs/5534
► Cylinder Two (http://chriszabriskie.com/cylinders/) by Chris Zabriskie (http://chriszabriskie.com/); licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/)
► “Fable” by Stephen Keech, licensed through SoundStripe.com: https://app.soundstripe.com/songs/6312
► “Selha” by Stephen Keech, licensed through SoundStripe.com: https://app.soundstripe.com/songs/7102

Further reading and resources:
► Echeverria, F., Klinkhammer, G. & Thorne, K. S. (1991), “Billiard balls in wormhole spacetimes with closed timelike curves: Classical theory”, Phys. Rev. D., 44, 1077: https://ui.adsabs.harvard.edu/abs/1991PhRvD…44.1077E/abstract.
► S. Kalyana Rama & Siddhartha Sen (1994), “Inconsistent Physics in the Presence of Time Machines”: https://arxiv.org/abs/gr-qc/9410031v1
► Stephen Hawking (1992), “Chronology protection conjecture”, Phys. Rev. D., 46603: https://ui.adsabs.harvard.edu/abs/1992PhRvD…46…603H/abstract.
► Max Tegmark (1997), “On the dimensionality of space time”, CQG, 14, L69: https://arxiv.org/abs/gr-qc/9702052

Films clips used:

Continue reading “Traveling Back in Time” | >

A hidden mechanism for achieving glides of hundreds of feet is revealed by computational modelling.

Scientists are currently thinking of ways to create robots resembling the gliding motion of flying snakes, according to a study published today (Dec .13) in Physics of Fluids.

‘Undulations’ encourage lift.

KaraGrubis/iStock.

The researchers anticipate their findings will improve our comprehension of gliding motion and result in a more effective design for future airborne snake robots.

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“I wouldn’t want to be on the team figuring out how to build a Jupiter-sized spacecraft, but the odds aren’t zero.”

A team of scientists believes we may be able to detect alien spacecraft flying through distant solar systems using the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the US.

Though the scientists from Applied Physics, a research institute in New York, concede that gravitational wave (GW) detection is “in its infancy”, they also say it is “a sophisticated science” that could be used to “detect extra-terrestrial mega-technology,” in a paper available in pre-print server arXiv.

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Fusion Energy For All Humanity — Prof Dr. Tony Donné Ph.D. — Program Manager (CEO), EUROfusion

Prof. Dr. Tony Donne, Ph.D. is Program Manager (CEO) of the EUROfusion (https://www.euro-fusion.org/) research consortium, a European consortium of 30 national fusion research institutes, in 26 EU countries, plus Switzerland and Ukraine, where he coordinates the work of over 4,000 scientists and engineers.

Dr. Donne trained as a physicist, obtaining his Masters in Experimental Physics at Utrecht University, his Ph.D. degree at the Free University of Amsterdam for work in the field of nuclear physics, and moved into fusion research right afterwards and has devoted a substantial part of his scientific career to the design and use of plasma diagnostics in a large range of fusion devices.

Prior to EUROfusion, Dr. Donne was head of the Fusion Physics Division at the Dutch Institute for Fundamental Energy Research (DIFFER) and responsible for the coordination of the nuclear fusion research in the Netherlands, where he coordinated Dutch fusion research as Director of fusion science and Acting Director.

Dr. Donne has also served as Professor in Diagnostics and Heating of Fusion Plasmas at Eindhoven University of Technology, Director of the Dutch-Russian Centre of Excellence on Fusion Physics and Technology, as well as Program Director of the ITER (International Thermonuclear Experimental Reactor)-Netherlands consortium, and chair of the Coordination Committee of the International Tokamak Physics Activity under the auspices of the ITER project.

Continue reading “Prof. Dr. Tony Donne, Ph.D. — Program Manager (CEO), EUROfusion — Fusion Energy For All Humanity” | >

Life is really weird. From the vantage point of a physicist, it is even stranger. Life is unlike any other phenomenon in physics. Stars, electrons, and black holes are all amazing in their own ways. But only life invents, and the first thing life invents is itself.

Life is creative in a way that no other physical system can be, and its unique use of information may be the key to understanding what makes it different from other physical systems. Now, thanks to a new grant my colleagues and I have received from the Templeton Foundation, we are going to be exploring exactly how information allows life to work its magic. I’m very excited about the project, and this essay is my first report from the frontier as we plunge into terra incognita.

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We still don’t have a clear picture of the Sun’s physics — but the Solar Ring could change that.

To solve this a team of astronomers proposes the Solar Ring. The Solar Ring is a fleet of three spacecraft that will all orbit around the Sun. They will be separated from each other by 120 degrees and be fitted with identical instruments. This way their overlapping fields of view will make it impossible for us to miss anything happening on the surface.

Among the many kinds of observations that the astronomers behind the Solar Ring hope to perform, one involves a technique called reverberation mapping. By carefully mapping the velocity of gas on the surface of the Sun, they can measure vibrations and pulsations. These kinds of “sunquakes” give astronomers rich information about what is happening within deeper layers, much like how earthquakes tell us about the core and mantle of the Earth.

The Solar Ring will also be able to catch the beginnings of a solar flare or an eruption event no matter where it happens on the Sun, providing even more early warning for space weather. These kinds of plasma storms can disrupt satellites and even affect electrical systems on the Earth’s surface, so the more warning, the better.

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Clues to a black hole’s origins can be found in the way it spins. This is especially true for binaries, in which two black holes circle close together before merging. The spin and tilt of the respective black holes just before they merge can reveal whether the invisible giants arose from a quiet galactic disk or a more dynamic cluster of stars.

Astronomers are hoping to tease out which of these origin stories is more likely by analyzing the 69 confirmed detected to date. But a new study finds that for now, the current catalog of binaries is not enough to reveal anything fundamental about how black holes form.

In a study appearing today in the journal Astronomy and Astrophysics, MIT physicists show that when all the known binaries and their spins are worked into models of black hole formation, the conclusions can look very different, depending on the particular model used to interpret the data.

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