Our understanding of gravity and black holes is currently in a funny spot that looks a little similar to how physics in general looked before quantum mechanics. Before quantum mechanics, scientists were puzzled by the stability of atoms. Shouldn't the negatively charged electrons simply fall into the positively charged nucleus? Also, the electrostatic force between charges was known to increase the closer two charged objects were to one another, and by naive extrapolation, this force should become infinite as the distance between objects goes to zero. This is known as a `singularity' in the theory. Singularities are usually a sign that our theory is being extrapolated beyond where it is applicable.

Quantum mechanics held the solution to the puzzle: electrons don't spiral around the nucleus; they sit in quantum orbits that can only take on certain discrete levels.

In our current understanding of gravity, there are objects predicted by the theory known as black holes. But just like with `classical' atoms, these objects are pretty weird. They have singularities right at the center, and just like the electrons orbiting an atomic nucleus, the classical theory of gravity says that matter should spiral into a black hole to meet the singularity. On the way, they cross an event horizon from which they can never return, and which shields anyone from looking into the black hole.

The singularity is an indication that our classical theory of gravity is somehow breaking down. But where? If we try to merge quantum mechanics with black holes, a clue arises: `Hawking' radiation is predicted by the merger to emanate from the black hole horizon, and this radiation leads to the evaporation of black holes, and the loss of all the information of anything that fell in.

But this behavior appears to break quantum mechanics because in quantum theory, information cannot be destroyed. It can be scrambled, transformed, hidden, but never fundamentally erased.

This is the black hole information paradox: the merger of our best gravitational theory and quantum theory seems to lead to information loss, which is incompatible with quantum theory.

In this episode of the podcast, I speak with theorist Niayesh Afshordi. He suggests that the black hole information paradox arises because we are extrapolating our equations beyond where they make sense. His suggestion is a little unorthodox: black holes have no center. The horizon must be replaced with a surface, beyond which there is nothing. I speak with him to try to understand his suggestion.

►Watch on Youtube: https://www.youtube.com/watch?v=68qwzsjmoxU&list=PLnE3V9mcAvmYosrFCguPfGnFeI_CChb1j&index=1

►Find out more about Niayesh's work: https://nafshordi.com/

►Follow Niayesh on Twitter: @nafshordi

#BlackHoles, #QuantumMechanics, #QuantumPhysics, #HawkingRadiation, #BlackHoleInformationParadox, #Gravity, #TheoreticalPhysics, #Physics #NiayeshAfshordi, #GeneralRelativity

This publication is based upon work from COST Action RQI CA23115, supported by COST (European Cooperation in Science and Technology). COST is a funding agency for research and innovation networks. Our Actions help connect research initiatives across Europe and enable scientists to grow their ideas by sharing them with their peers. This boosts their research, career and innovation. For more information see: www.cost.eu.

What makes a bioweapon effective? What are researchers actually capable of creating in the lab? What pathogens are kept in storage? How realistic is a large scale catestrophic attack using a bioweapon?

In this conversation I speak with Kevin Esvelt, who is an associate professor at the MIT Media Lab, where he leads the Sculpting Evolution Group in advancing biotechnology safely. Kevin was one of the pioneering researchers behind gene drive technology. In 2013, recognizing the potential dangers of the technology, he and his colleagues chose to break with scientific tradition by revealing their findings and calling for open discussion and safeguards before building the first CRISPR-based gene drive system and demonstrating reversibility in the laboratory.

Kevin now focuses on accelerating beneficial advances while safeguarding biotechnology against mistrust and misuse. Projects include building catalytic platforms for directed evolution, pioneering new ways of developing ecotechnologies with the guidance of local communities, developing early-warning systems to reliably detect any catastrophic biological threat, applying cryptographic methods to enable secure and universal DNA synthesis screening, and advising policymakers on how best to mitigate global catastrophic biorisks. We discuss the state of the art in pathogen development, as well as the tools available to safegaurd humanity. ►Watch on Youtube: https://youtu.be/SLj8vwliQp0

►You can find out more about Kevin's work here: https://www.sculptingevolution.org/kevin-m-esvelt

►Follow Kevin on X: @kesvelt

The black hole information paradox sits at the intersection of quantum mechanics and general relativity, two of our most successful theories of nature.

According to classical general relativity, anything that crosses the event horizon of a black hole is lost to the outside universe forever. Black holes are almost featureless. It doesnt matter if you build one from tea pots, or elephants, the information of what fell in is hidden forever.

But quantum mechanics tells a different story. In quantum theory, information cannot be destroyed. It can be scrambled, transformed, hidden, but never fundamentally erased. So what happens when these two ideas collide in the most extreme environment in the universe?

If a black hole forms from a star and later evaporates through Hawking radiation, what happens to the information about everything that fell in? Does it come back encoded in the radiation? Does it remain trapped forever? Or does physics itself break down at the boundary?

To make this concrete, imagine throwing a book into a black hole. If the black hole eventually evaporates completely, the total mass returns to the universe as radiation, but what happens to the detailed information inside that book? The words, the structure, the arrangement of matter that defined it? Depending on how you answer that question, you either preserve one of the deepest principles in quantum theory, or you are forced to accept that something fundamental about our understanding of reality is incomplete.

In this conversation, I speak with theoretical physicist Carlo Rovelli, one of the leading voices in quantum gravity, to explore the black hole information paradox. He outlines what the paradox is, explains where he belives many physicists get themselves confused, and puts forward his own solution to the paradox. ►Watch on YouTube: https://www.youtube.com/watch?v=vjsof8VfOM0&list=PLnE3V9mcAvmYosrFCguPfGnFeI_CChb1j&index=2https://youtu.be/vjsof8VfOM0

►You can find out more about Carlo's work here: https://www.cpt.univ-mrs.fr/~rovelli/

►Follow Carlo on Twitter: @carlorovelli

This publication is based upon work from COST Action RQI CA23115, supported by COST (European Cooperation in Science and Technology). COST is a funding agency for research and innovation networks. Our Actions help connect research initiatives across Europe and enable scientists to grow their ideas by sharing them with their peers. This boosts their research, career and innovation. For more information see: www.cost.eu