A new argument explores how the growth of disorder could cause massive objects to move toward one another. Physicists are both interested and skeptical.
Category: physics – Page 24
With potential implications for mechanical systems, study reveals physics of the ‘nick shot’ in squash
In squash, the “nick shot” is an emphatic, point-ending play in which a player strikes a ball that ricochets near the bottom of the wall and rolls flat along the floor instead of bouncing, leaving an opponent with no chance to return it.
While the shot is as old as the game itself, a team of researchers has now revealed the physics behind it, showing how perfect placement and just the right roll conspire to kill the ball’s bounce.
The research, led by Brown University Professor of Engineering Roberto Zenit, was published in Proceedings of the National Academy of Sciences. While the findings could be useful in developing shock-dampening technologies, Zenit says the work grew out of his interest in using science to explain the everyday world.
The Center of Our Universe Does Not Exist. A Physicist Explains Why
About a century ago, scientists were struggling to reconcile what seemed a contradiction in Albert Einstein’s theory of general relativity.
Published in 1915, and already widely accepted worldwide by physicists and mathematicians, the theory assumed the Universe was static – unchanging, unmoving and immutable. In short, Einstein believed the size and shape of the Universe today was, more or less, the same size and shape it had always been.
But when astronomers looked into the night sky at faraway galaxies with powerful telescopes, they saw hints the Universe was anything but that. These new observations suggested the opposite – that it was, instead, expanding.
Earth-based telescopes offer a fresh look at Cosmic Dawn
For the first time, scientists have used Earth-based telescopes to look back over 13 billion years to see how the first stars in the universe affect light emitted from the Big Bang.
Using telescopes high in the Andes mountains of northern Chile, astrophysicists have measured this polarized microwave light to create a clearer picture of one of the least understood epochs in the history of the universe, the Cosmic Dawn.
“People thought this couldn’t be done from the ground. Astronomy is a technology-limited field, and microwave signals from the Cosmic Dawn are famously difficult to measure,” said Tobias Marriage, project leader and a Johns Hopkins professor of physics and astronomy. “Ground-based observations face additional challenges compared to space. Overcoming those obstacles makes this measurement a significant achievement.”
There’s an infinite amount of energy locked in the vacuum time. Could we ever use it?
The bottom line is that no matter what the zero-point energy is, it’s the background of the universe on top of which all of physics takes place. Just as you can’t go lower than the ground floor of a building with no basement, you can’t get lower than the ground state of the universe — so there’s nothing for you to extract, and there’s no way to leverage that into useful applications of energy.
So, unfortunately, any work you do in the universe will have to be done the old-fashioned way.
Self-learning neural network cracks iconic black holes
A team of astronomers led by Michael Janssen (Radboud University, The Netherlands) has trained a neural network with millions of synthetic black hole data sets. Based on the network and data from the Event Horizon Telescope, they now predict, among other things, that the black hole at the center of our Milky Way is spinning at near top speed.
The astronomers have published their results and methodology in three papers in the journal Astronomy & Astrophysics.
In 2019, the Event Horizon Telescope Collaboration released the first image of a supermassive black hole at the center of the galaxy M87. In 2022, they presented an image of the black hole in our Milky Way, Sagittarius A*. However, the data behind the images still contained a wealth of hard-to-crack information. An international team of researchers trained a neural network to extract as much information as possible from the data.
Galactic Empire Psychology
We now know that the Galaxy is full of potentially habitable planets. So why do we see no signs that any civilizations have come before us? Matt O’Dowd, astrophysicist and host of PBS Space Time, explains why Fermi’s paradox really is so surprising, and he offers a new piece of evidence that may point towards the solution.
Astrophysicist Matthew O’Dowd spends his time studying the universe, especially really far-away things like Quasars, super-massive black holes and evolving galaxies. He completed his Ph.D. at NASA´s Space Telescope Science Institute, followed by work at the University of Melbourne and Columbia University. Currently he is a professor at the City University of New York´s Lehman College and an Associate at the American Museum of Natural Historys Hayden Planetarium.
Thumbnail © Nadja Niemiec.
This talk was given at a TEDx event using the TED conference format but independently organized by a local community.
New idea explains dark energy AND dark matter (maybe)
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Dark energy and dark matter are two placeholders for mysterious forces and substances that expand our universe and make up the majority of its matter, respectively. In a new theory, one physicist says that defects in spacetime explain both of these mysteries at the same time. Let’s take a look.
This video comes with a quiz which you can take here: https://quizwithit.com/start_thequiz/1748971420417x503138930832703500
Correction: I mixed up the gems, sorry. I should have said, defects change the colour of sapphires to red and green, not diamonds.
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