The TOE that Maxwell missed

If you’ve ever read James Clerk Maxwell’s 1865 paper A Dynamical Theory of the Electromagnetic Field, you might have noticed his Note on the Attraction of Gravitation. It’s at the end of part IV. Maxwell ends up saying energy is essentially positive, and that “the presence of dense bodies influences the medium so as to diminish this energy wherever there is a resultant attraction”. Then he said this: “As I am unable to understand in what way a medium can possess such properties, I cannot go…

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Supergravity

Clunk. That’s the sound of my head hitting my desk. Because the $3m special breakthrough prize has just been awarded to the “discoverers” of supergravity. Yes folks, that’s one of those mathematical “discoveries”. It isn’t like discovering America or penicillin. It’s the sort of “discovery” that people peddle when they’re hyping a hypothesis for which there’s no evidence at all. The prize was awarded to Sergio Ferrara, Daniel Freedman, and Peter van Nieuwenhuizen for an “Influential Theory Combining Gravity with Particle Physics”. Only it isn’t influential…

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Misconceptions in gravitational physics

I think it’s safe to say that there are some misconceptions in physics. The issue of course, is how many. That’s where I part company with your average physicist. He’ll tell you that whilst we don’t understand everything, we do understand some things, such as black holes. Only he doesn’t. Take a look at the Wikipedia black hole article. It says this: “a black hole is a region of spacetime exhibiting gravitational acceleration so strong that nothing - no particles or even electromagnetic radiation such as…

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Quantum gravity is a castle in the air

When you spend some time digging into the history of physics, you find yourself uncovering the foundations of physics, and then you come to appreciate a few things. You come to appreciate how gravity works, and why an electron falls down. It isn’t because gravitons are flying back and forth: Graviton image by Julie Peasley, see http://www.particlezoo.net/ You also come to appreciate that light interacts with light to form electrons and positrons in gamma-gamma pair production. You come to appreciate that the electron is not a…

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Dark matter

There’s plenty of evidence for dark matter, ranging from velocity dispersion, flat galactic rotation curves, and gravitational lensing. The evidence for dark matter is so good we can even map it out: Image credit NASA, ESA and R. Massey (California Institute of Technology), see spacetelescope.org There’s also plenty of papers and articles about dark matter candidates. Maxim Khlopov refers to WIMPs, axions, neutrinos, mirror-world particles, extra-dimensional particles, and black holes. Andreas Ringwald refers to neutralinos, gravitinos, sterile neutrinos, and axions. Kim Griest refers to MACHOs, molecular…

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Dark matter candidates

Everybody loves a mystery, and one of the best mysteries in physics is dark matter. As to where it starts, check out Brian Koberlain who said its origins can be traced to the 1600s. Or Alexis Bouvard who in 1821 said anomalies in the orbit of Uranus could be caused by dark matter. Or see the Ars Technica history of dark matter article by Stephanie Bucklin. She said in 1884 Lord Kelvin concluded that “many of our supposed thousand million stars, perhaps a great majority of…

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Firewall!

The black hole firewall is a relatively recent idea. On Wikipedia you can read how it “was proposed in 2012 by Ahmed Almheiri, Donald Marolf, Joseph Polchinski, and James Sully as a possible solution to an apparent inconsistency in black hole complementarity”. Their proposal is known as the AMPS firewall, and the title of their paper is black holes: complementarity or firewalls? They cannot all be true They start by saying “we argue that the following three statements cannot all be true: (i) Hawking radiation is…

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Hawking radiation

Everybody knows about Hawking radiation. It’s been on TV. See the YouTube clip from the Channel 4 documentary Stephen Hawking: master of the universe. That’s where Kim Weaver of NASA says black holes offer an ultimate test of the physics of the universe. She says they’re cauldrons of heat and light with jets and particles coming out at half the speed of light, and an enormous amount of stuff going on. She finishes up saying and that’s exciting. I absolutely agree. Because yes, I think black…

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Black holes

We can trace black holes all the way back to John Michell in 1783. He's the man who devised the torsion balance used by Henry Cavendish to determine the mass of the Earth. Michell was something of an expert on gravity. He talked about “dark stars”, and said this: "if there should really exist in nature any bodies, whose density is not less than that of the sun, and whose diameters are more than 500 times the diameter of the sun, since their light could not…

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The principle of equivalence and other myths

Once you know that an optical clock goes slower when it’s lower because light goes slower when it’s lower, you soon understand why light curves. Not because it follows the curvature of spacetime. Because the speed of light is spatially variable, like Einstein said. Then once you know about the wave nature of matter and electron spin, you soon understand why matter falls down, and why the Newtonian deflection of matter is only half the deflection of light. Then once you know how gravity works, you…

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