Alex McColgan
speaker
28,638 appearances
102 recordings
1 series
first heard Nov 2024
last heard 5d ago
Alex McColgan’s voice in public audio — every appearance, attributed to the second.
Trend
recordings per month · last 12 monthsRecordings per month over the last 12 months — 66 in all, peaking in Aug 2026 with 11.
Appearances
In this analogy, a spin up particle is called right-handed, while a spin down particle is called left-handed.
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The second, and even crazier surprise, was that right-handed antiparticles experienced a different strength of the weak force as compared to left-handed ordinary particles.
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In practice, this means that the quantum probabilities for radioactive decay in ordinary nuclei are somewhat different from the probabilities of the analogous decay processes in antinuclei.
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This fundamental asymmetry between particles and antiparticles was first observed in a 1963 experiment run by James Cronin and Val Fitch of Princeton University, who would be awarded yet another Nobel Prize for their discovery.
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When this asymmetry was discovered, there was some hope that it would explain the baryonic asymmetry of the universe.
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Perhaps these differences in the weak force were responsible for the abundance of matter and utter lack of antimatter around us.
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But the maths didn't quite work out.
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There simply wasn't enough of a difference between the strength of the weak force acting on particles versus antiparticles.
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That was when physicists began to turn their attention to the strong nuclear force.
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Theoretical models predicted that, just like in the weak interaction, there should be some differences in how left-handed particles and right-handed particles feel the strong force.
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But antimatter just keeps surprising us.
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Every experiment to date suggests that the strong force treats particles and antiparticles just the same.
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This brings us to the last of the four fundamental forces and the subject of today's ongoing experiments at CERN, gravity.
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To be honest, suggesting that gravity might treat matter and antimatter differently is kind of a long shot.
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Think back to the popular legend of Galileo tossing stones of different sizes and materials from the Tower of Pisa.
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They all fell at the same rate because the gravitational acceleration on Earth is 9.8 m per second squared, regardless of which object is falling.
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Of course, the experiment works even better in a vacuum chamber.
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where air resistance is taken out of the equation.
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Newton expanded on this idea and showed in the 17th century that your gravitational acceleration anywhere in space depends only on the mass of the object pulling you and your distance from it, but not on any of your personal properties, not even your own mass.
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This famous result, known as the equivalence principle, is the foundation of Einstein's theory of general relativity, our most accurate and successful model of gravity to date.
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Showing 1561–1580 of 28,638 · page 79 of 1432
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