Lifeboat Foundation

If you were to travel back in time to kill your grandparents — let’s ignore the ‘why’ here, for the sake of argument — you would never have been born. Which means there was nobody to kill your grandparents. Which means you were actually born after all, which… hold up, what’s going on here?!

These kinds of brain-breaking paradoxes have been puzzling us forever, inspiring stories ranging from “Back to the Future” to “Hot Tub Time Machine.”

Now, New Scientist reports that physicists Barak Shoshany and Jacob Hauser from the Perimeter Institute in Canada have come up with an apparent solution to these types of paradoxes that requires a very large — but not necessarily infinite — number of parallel universes.

MIT physicists are reigniting the possibility, which they previously had snuffed out, that a bright burst of gamma rays at the center of our galaxy may be the result of dark matter after all.

For years, physicists have known of a mysterious surplus of energy at the Milky Way’s center, in the form of gamma rays—the most energetic waves in the electromagnetic spectrum. These rays are typically produced by the hottest, most extreme objects in the universe, such as supernovae and pulsars.

Gamma rays are found across the disk of the Milky Way, and for the most part physicists understand their sources. But there is a glow of gamma rays at the Milky Way’s center, known as the galactic center excess, or GCE, with properties that are difficult for physicists to explain given what they know about the distribution of stars and gas in the galaxy.

Abstract: In the context of warped extra-dimensional models with all fields propagating in the bulk, we address the phenomenology of a bulk scalar Higgs boson, and calculate its production cross section at the LHC as well as its tree-level effects on mediating flavor changing neutral currents. We perform the calculations based on two different approaches. First, we compute our predictions analytically by considering all the degrees of freedom emerging from the dimensional reduction (the infinite tower of Kaluza Klein modes (KK)). In the second approach, we perform our calculations numerically by considering only the effects caused by the first few KK modes, present in the 4-dimensional effective theory. In the case of a Higgs leaking far from the brane, both approaches give the same predictions as the effects of the heavier KK modes decouple. However, as the Higgs boson is pushed towards the TeV brane, the two approaches seem to be equivalent only when one includes heavier and heavier degrees of freedom (which do not seem to decouple). To reconcile these results it is necessary to introduce a type of higher derivative operator which essentially encodes the effects of integrating out the heavy KK modes and dresses the brane Higgs so that it looks just like a bulk Higgs.

On 13 December, Amazon Prime will air the fourth season of The Expanse, a hardboiled space drama renowned for its working-class characters and real-world space physics. Showrunner Naren Shankar is part of the reason the science checks out. The veteran writer and producer for programs such as Star Trek: The Next Generation, Farscape, and the police procedural CSI: Crime Scene Investigation, has a doctorate in applied physics and electrical engineering.

Shankar chatted with about why he feels it’s important to have a realistic sci-fi show, and how television work is like the scientific peer-review process.

This interview has been edited for clarity and length.

Gravitational waves leave behind a memory — a permanent bend in space-time — as they pass through.

Researchers fabricated a cavity device with a large number of “exceptional points,” which are modes that exhibit exotic phenomena, such as extreme sensitivity to external parameters.

One of the fundamental laws of physics is that energy is conserved, but many local physical systems—seen in isolation—gain or lose energy. For example, a light bulb converts electrical power into radiation, which from the perspective of the electrical circuit is a loss of energy. By contrast, a light beam gains energy as it passes through an amplifying medium. Although one can model the inputs and outputs, it’s often mathematically simpler to just treat energy as a locally nonconserved quantity. Nonconservative systems, referred to as non-Hermitian, have attracted a great deal of interest because they can exhibit potentially useful phenomena, such as enhanced sensing [1] and robust single-mode lasing [2]. These phenomena are intimately related to the ability of non-Hermitian systems to support exceptional points, a type of degeneracy in which two or more modes suddenly coalesce into one (Fig. 1).

The system could allow scientsts to better understand how infants perceive the world.

An École Polytechnique Fédérale de Lausanne (EPFL) Bachelor’s student has solved a mystery that has puzzled scientists for 100 years. He discovered why gas bubbles in narrow vertical tubes seem to remain stuck instead of rising upwards. According to his research and observations, an ultra-thin film of liquid forms around the bubble, preventing it from rising freely. And he found that, in fact, the bubbles are not stuck at all – they are just moving very, very slowly.

Air bubbles in a glass of water float freely up to the surface, and the mechanisms behind this are easily explained by the basic laws of science. However, the same laws of science cannot explain why air bubbles in a tube a few millimeters thick don’t rise the same way.

Physicists first observed this phenomenon nearly a century ago, but couldn’t come up with an explanation – in theory, the bubbles shouldn’t encounter any resistance unless the fluid is in motion; thus a stuck bubble should encounter no resistance.

For the first time, physicists have calculated exactly what kind of singularity lies at the center of a realistic black hole.