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Category: physics – Page 169

Boltzmann Brains: A Cosmological Horror Story

Boltzmann brains are perhaps one of the spookiest ideas in physics. A Boltzmann brain is a single, isolated human brain complete with false memories that spontaneously fluctuates into existence from the void. They’re the kind of thing you’d find in a campfire horror story. The big problem, however, is that a range of plausible cosmological models (including our current cosmology) predict that Boltzmann brains will exist. Even worse, these brains should massively outnumber “ordinary” conscious observers like ourselves. At every moment of your existence, it is more likely that you are an isolated Boltzmann brain, falsely remembering your past, than a human being on a rocky planet in a low-entropy universe.

In this video I explain where the idea of Boltzmann brains originated, and why they haunt modern cosmology.

Thanks for watching, and I hope you enjoyed! Please like and subscribe for more videos on amazing ideas in physics.

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The Light Clock: How Moving Clocks Run Slow

If you know anything about special relativity then you probably know that how fast you’re moving has an impact on how quickly time passes for you. What physics gives rise to this effect? Do you need to know some complicated mathematics in order to understand it?

It turns out that this effect, known as “time dilation”, can be very easily derived for a special kind of clock: a light clock. In this video, I consider a light clock moving through space and show how the postulates of special relativity entail that this moving clock runs slow.

Watch the video to learn what the two postulates of Einstein’s Special Relativity are, and why they entail that moving clocks slow down.

Thanks for watching, and I hope you enjoyed! Please like and subscribe for more videos on amazing ideas in physics.

Winter Ride by Twin Musicom is licensed under a Creative Commons Attribution 4.0 license. https://creativecommons.org/licenses/by/4.0/

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If you could see a black hole, it might look like a cosmic koosh ball

Year 2022 face_with_colon_three

Since the discovery of black holes, they have inspired images of the universe’s extremities in both scientists and storytellers. Their immense gravity — sucking in any matter and light unfortunate enough to come within grabbing distance — conjures images of crushing death and infinite possibility.

That same gravity, however, creates a well which consumes indiscriminately and from whence nothing can ever emerge. The only trouble is that isn’t the case. Among Stephen Hawking’s many accomplishments was the discovery that black holes actually radiate very slowly and will eventually evaporate. This discovery, while enough to make Hawking famous, threw a wrench in contemporary astrophysics by creating a paradox.

If a black hole compresses into a singular point at its center and is surrounded by a gravitational event horizon, then the radiation emerging from the horizon is necessarily separate from the matter in the middle. In short, that radiation contains none of the information related to the matter which fell inside. If that’s true, then causality essentially breaks down around a black hole and physicists didn’t like that one bit.

A new physics-defying theory describes the effects of faster-than-light travel

Extended special relativity describes how the universe would look if you broke the speed of light.

Scientists from the University of Warsaw in Poland and the National University of Singapore are pushing the limits of relativity with a new theory called the “extension of special relativity,” a report from Science Alert reveals.

The scientists’ new study suggests that objects may be able to go faster than the speed of light without completely shattering our current laws of physics.

Gremlin/iStock.

The new theory combines three time dimensions with a single space dimension (“1+3 space-time”), providing an alternative, mind-bending scenario to the three spatial dimensions and one time dimension we all know.

A big problem with fusion is solved leading us near to a perpetual energy source

Image credit: Max Planck Institute of Plasma physics. Cutaway of a Fusion Reactor.

A team of researchers from the Max Planck Institute for Plasma Physics (IPP) and the Vienna University of Technology (TU Wein) have discovered a way to control Type-I ELM plasma instabilities, that melt the walls of fusion devices. The study is published in the journal Physical Review Letters.

There is no doubt that the day will come when fusion power plants can provide sustainable energy and solve our persistent energy problems. It is the main reason why so many scientists around the world are working on this power source. Power generation in this way actually mimics the sun.

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