Mysteries of physics summary

Here’s my summary of my feedback to the 18 biggest unsolved mysteries in physics by Natalie Wolchover and Jesse Emspak: Mysteries of physics part1 What is dark energy? Think of the universe expanding because space has an innate pressure, like a squeezed-down stress ball. Then think of a bubble-gum balloon in vacuum. As it expands the skin gets thinner and weaker, and less able to resist the further expansion. So it expands further, so the skin gets even thinner and weaker, and so on. So the…

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Mysteries of physics part4

This is the fourth and final section of mysteries of physics. I’m working through the 18 biggest unsolved mysteries in physics by Natalie Wolchover and Jesse Emspak. In doing so I’m forming an opinion that some mysteries are nothing of the kind. I’m also forming an opinion that some physicists and institutions peddle mystery in order to promote themselves, because they aren’t doing useful science. More on that another day. Meanwhile, on with the show: When sound waves make light Though particle-physics questions account for many…

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Mysteries of physics part3

Again carrying on from last week, I’m working through the 18 biggest unsolved mysteries in physics by Natalie Wolchover and Jesse Emspak. I’ve done the first nine. The next topic concerns grand unified theories, the sort of thing Alan Guth was thinking of when he came up with inflation. A grand unified theory or GUT is said to be a step toward a theory of everything or TOE. Do the universe's forces merge into one? The universe experiences four fundamental forces: electromagnetism, the strong nuclear force, the…

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Mysteries of physics part2

Carrying on from last week, I’m working through the 18 biggest unsolved mysteries in physics by Natalie Wolchover and Jesse Emspak. Of course, not everybody would come up with the same list, so if there’s anything you’d like me to talk about, please drop me a line using the contact form. OK, where were we? We’ve had dark energy, dark matter, the arrow of time, parallel universes, and the mystery of the missing antimatter. Next is the fate of the universe: What is the fate of…

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Mysteries of physics part1

When I google on mysteries of physics, a whole pile of websites comes up. Top of the list is the 18 biggest unsolved mysteries in physics. It’s a Livescience article written by Natalie Wolchover and Jesse Emspak. It makes for interesting reading, especially for me. That’s because I’m the physics detective. I solve mysteries. Some people don’t. Instead some people peddle mystery. Because mystery sells, just like quantum sells. That’s why CERN peddle the myth that antimatter might fall up, even though everybody who knows about…

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The double slit experiment

There’s a nice little physicsworld article dating back to 2002. It was written by then-editor Peter Rodgers, and it started by asking “What is the most beautiful experiment in physics?” The answer was, of course, the double slit experiment, which was first performed by Thomas Young in 1801: Double slit experiment image from the curiosity makes you smarter article by Ashley Hamer People refer to the double slit experiment as an example of the weirdness of quantum physics. Or to promote weird ideas such as the…

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What energy is

If you ask what is energy? some people will tell you that energy is an abstract thing. This was how Richard Feynman described it in the Feynman lectures, volume I chapter 4. He used the analogy of children’s blocks. He said these blocks were absolutely indestructible and could not be divided. But then he said there are no blocks. Only then he contradicted himself by saying energy has a number of different forms, such as gravitational energy, kinetic energy, and heat energy: Image from Assignment point…

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The fate of the universe

One of the things cosmologists like to talk about is the fate of the universe. Some say it all depends on the density parameter omega: Ω. This started life as the average matter density of the universe divided by a “critical” matter density for the Friedmann universe: Based on the Friedmann universes public domain image by BenRG, see Wikipedia Commons and Wikipedia Nowadays when we talk about omega we don’t restrict ourselves to matter alone. That’s because energy doesn’t necessarily take the form of matter, and…

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The edge of the universe

When you dig into the history of cosmology, some things catch your eye. Things like the “boundary conditions” in Einstein’s 1917 cosmological considerations in the general theory of relativity. Or something Willem de Sitter said in his 1917 paper On the relativity of inertia. Remarks concerning Einstein's latest hypothesis. He said this: “if the gμν at infinity are zero of a sufficiently high order, then the universe is finite in natural measure”. There’s also something Paul Steinhardt said in his 1982 Natural Inflation paper. He said this:…

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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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