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The Physicist Who Says We’ve Already Quantized Gravity

Professor John Donoghue explains why quantum physics and gravity actually work perfectly together. He tackles quadratic gravity, effective field theory, and random dynamics, arguing that grand unification and naturalness aren’t required for a theory of everything.

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    • 00:00:00 — Limits of Quantum Mechanics
    • 00:06:35 — Effective Field Theory
    • 00:12:24 — Gravity: Geometry or Force?
    • 00:18:46 — QFT and Gravity Tension
    • 00:24:59 — Quadratic Gravity Theory
    • 00:34:16 — Dueling Arrows of Causality
    • 00:41:57 — Random Dynamics and Anti-Unification
    • 00:48:13 — The Naturalness Problem
    • 00:53:40 — Questioning Hidden Assumptions

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    TIMESTAMPS:

    Supernova from the dawn of the universe captured by James Webb Space Telescope

    An international team of astronomers has achieved a first in probing the early universe, using the James Webb Space Telescope (JWST), detecting a supernova—the explosive death of a massive star—at an unprecedented cosmic distance.

    The explosion, designated SN in GRB 250314A, occurred when the universe was only about 730 million years old, placing it deep in the era of reionization. This remarkable discovery provides a direct look at the final moments of a massive star from a time when the first stars and galaxies were just beginning to form.

    The event, which has been reported on in the recently published academic paper JWST reveals a supernova following a gamma-ray burst at z ≃ 7.3, (Astronomy & Astrophysics, 704, December 2025), was initially flagged by a bright burst of high-energy radiation, known as a long-duration Gamma-Ray Burst (GRB), detected by the space-based multi-band astronomical Variable Objects Monitor (SVOM) on March 14, 2025. Follow-up observations with the European Southern Observatory’s Very Large Telescope (ESO/VLT) confirmed the extreme distance.

    Research uncovers the telltale tail of black hole collisions

    When black holes collide, the impact radiates into space like the sound of a bell in the form of gravitational waves. But after the waves, there comes a second reverberation—a murmur that physicists have theorized but never observed.

    An international collaboration has for the first time simulated in detail what these whispers—called late-time gravitational wave tails —might “sound” like.

    “So far, we’ve only seen tails in simplified models, not in full simulations of numerical relativity,” said Leo Stein, University of Mississippi associate professor of physics and astronomy and co-author of the study. “These are the first fully numerical simulations where we saw tails clearly.”

    Dark Matter Breakthrough: Physicists Crack “Big Bang Theory” Puzzle

    A new theoretical study suggests fusion reactors could do more than generate energy, they might also produce particles linked to dark matter. Researchers at the University of Cincinnati say they have worked out, at least on paper, how fusion reactors could produce subatomic particles known as axi

    Cosmic knots may finally explain why the Universe exists

    Knotted structures once imagined by Lord Kelvin may actually have shaped the universe’s earliest moments, according to new research showing how two powerful symmetries could have created stable “cosmic knots” after the Big Bang. These exotic objects may have briefly dominated the young cosmos, unraveled through quantum tunneling, and produced heavy right-handed neutrinos whose decays tipped the balance toward matter over antimatter.

    In 1867, Lord Kelvin pictured atoms as tiny knots in an invisible medium called the ether. That picture turned out to be wrong, since atoms are built from subatomic particles rather than twists in space. Yet his discarded idea of knotted structures may still help explain one of the deepest questions in science: why anything in the universe exists at all.

    A team of physicists in Japan has now shown that knotted structures can naturally appear in a realistic particle physics model that also addresses several major mysteries, including the origins of neutrino masses, dark matter, and the strong CP problem. Their study, published in Physical Review Letters, suggests that such “cosmic knots” could have formed in the violently changing early universe, briefly taken over as a dominant form of energy, and then collapsed in a way that slightly favored matter over antimatter. As they formed and decayed, these knots would have stirred spacetime itself, producing a distinctive pattern of gravitational waves that future detectors might be able to pick up, which is rare for a problem that is usually very difficult to test directly.

    Bazinga! Physicists crack a ‘Big Bang Theory’ problem that could help explain dark matter

    A professor at the University of Cincinnati and his colleagues have figured out something two of America’s most famous fictional physicists couldn’t: how to theoretically produce subatomic particles called axions in fusion reactors.

    Particle physicists Sheldon Cooper and Leonard Hofstadter, roommates in the sitcom “The Big Bang Theory,” worked on the problem in three episodes of Season 5, but couldn’t crack it.

    Now UC physics Professor Jure Zupan and his theoretical physicist co-authors at the Fermi National Laboratory, MIT and Technion–Israel Institute of Technology think they have one solution in a study published in the Journal of High Energy Physics.

    Physicists Propose First-Ever Experiment To Manipulate Gravitational Waves

    When massive cosmic objects such as black holes merge or neutron stars crash into one another, they can produce gravitational waves. These ripples move through the universe at the speed of light and create extremely small changes in the structure of space-time. Their existence was first predicted by Albert Einstein, and scientists confirmed them experimentally for the first time in 2015.

    Building on this discovery, Prof. Ralf Schützhold, a theoretical physicist at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), is proposing a bold new step.

    Schützhold has developed a concept for an experiment that would go beyond detecting gravitational waves and instead allow researchers to influence them. The proposal, published in the journal Physical Review Letters, could also help clarify whether gravity follows quantum rules, a question that remains unresolved in modern physics.

    Surprising optics breakthrough could transform our view of the Universe

    FROSTI revolutionizes mirror control in gravitational-wave detectors, opening the door to a far deeper view of the cosmos. FROSTI is a new adaptive optics system that precisely corrects distortions in LIGO’s mirrors caused by extreme laser power. By using custom thermal patterns, it preserves mirror shape without introducing noise, allowing detectors to operate at higher sensitivities. This leap enables future observatories like Cosmic Explorer to see deeper into the cosmos. The technology lays the groundwork for vastly expanding gravitational-wave astronomy.

    Gravitational-wave detectors may soon get a major performance boost, thanks to a new instrumentation advance led by physicist Jonathan Richardson of the University of California, Riverside. In a paper published in the journal Optica, Richardson and his colleagues describe FROSTI, a full-scale prototype that successfully controls laser wavefronts at extremely high power inside the Laser Interferometer Gravitational-Wave Observatory, or LIGO.

    LIGO is an observatory that measures gravitational waves — tiny ripples in spacetime created by massive accelerating objects such as colliding black holes. It was the first facility to directly detect these waves, providing strong support for Einstein’s Theory of Relativity. Using two 4-km-long laser interferometers located in Washington and Louisiana, LIGO senses incredibly small disturbances, giving scientists a new way to study black holes, cosmology, and matter under extreme conditions.

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