Tag: Gravity

Feynman diagram Does antimatter ‘fall’ the same as matter? – QFT and CPT symmetry
General · Language · Problem

Does antimatter ‘fall’ the same as matter? – QFT and CPT symmetry

John Healy1 Comment

[“Quantum foundations” series – QFT charge inversion] As discussed elsewhere (e.g., in “QFT – How many fields are there?” and comments), in the Standard Model, “there is one field for each kind of particle.” So, consider the positron – the “negative-energy solution” of the Dirac equation. It’s likely that electrons and positrons (anti-electrons) are localized… Continue reading Does antimatter ‘fall’ the same as matter? – QFT and CPT symmetry

Book · General · Language · Problem

Reductionism in quantum physics – a naturalness mire?

John Healy3 Comments

[Draft] [“Beyond the Standard Model” series] Background on the “crisis” This Quanta Magazine article (below) has an eye-catching title, but its gist relates to the hierarchy problem, which I discussed in a prior post. That 2017 post (and additionaL commentary) used quotes by physicists – Sean Carroll, Leon Lederman, Fermilab’s Don Lincoln (video) – and… Continue reading Reductionism in quantum physics – a naturalness mire?

General · Language · Problem

Beyond the Standard Model – sliver of reality?

John Healy3 Comments

[Draft] [Beyond series] 2’s day. So, what’s the evidence that the Standard Model is incomplete? This Symmetry Magazine article cites some examples of why physicists seek something beyond the Standard Model. Is it convincing? • Symmetry Magazine > “Beyond the Standard Model” by Katrina Miller (02/22/2022) – The Standard Model is a quite successful best… Continue reading Beyond the Standard Model – sliver of reality?

General · Language · Problem

Getting and staying round – why are planets and moons spherical?

John Healy1 Comment

Imagine asking, à la a Jay Leno “Jaywalking” segment, some random people this question: “Why is our Moon round?” Or, “Why are planets always round (including the Earth) – like spheres – and not like a cube or a boulder or potato or other irregular solid?” Science communicator Ethan Siegel answered this question in a… Continue reading Getting and staying round – why are planets and moons spherical?

General · Language

The feather and the hammer

John Healy1 Comment

Modern physics is full of demonstrations which confound our everyday experience. There are some oldies but goodies, like the feather and the hammer. Remember Apollo 15 (1971)? These demonstrations illustrate the limits of everyday experience and provide interesting historical lessons. • Physics World > “The legend of the leaning tower” by Robert P Crease (04… Continue reading The feather and the hammer

General · Language · Media

Acceleration causes gravity, gravity causes acceleration

John Healy8 Comments

As I’ve written elsewhere,  I sometimes think that generations of scientists raised in space might help advance physics, having lived in a world dominated by inertia (rather than friction). Especially in regard to a visceral understanding of microgravity. Like characters in the TV series The Expanse. So, this Space.com article (June 18, 2018) “Relativity: The… Continue reading Acceleration causes gravity, gravity causes acceleration

General · Site

Surfing space-time — gravitational waves

John Healy1 Comment

Asymmetric gravitational interactions between two bodies produce gravitational waves.1 Such perturbations in space-time are so small that only the most massive interactions have been detected by LIGO, which uses laser interferometry and is “the largest and most ambitious project ever funded by the NSF.” While there was speculation about gravitational waves prior to Einstein’s theory… Continue reading Surfing space-time — gravitational waves

General · Language

GR: Chicken or egg redux

John Healy6 Comments

One of the major sources of confusion I’ve encountered in reading about modern physics is the discussion of gravity. No surprise, eh. Classical mechanics includes both Newtonian and relativistic mechanics. In Newtonian physics, gravity is an attractive force, which acts at a distance between all objects; and can be represented as a universal gravitational field.… Continue reading GR: Chicken or egg redux