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IM Egdall

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  • Location
    Hollywood, FL
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  • Favorite Area of Science
    modern physics
  • Biography
    Author of Einstein Relatively Simple: Our Universe Explained in Everyday Language.
  • Occupation
    I teach modern physics courses for the non-expert at several lifelong learning institutes in South Florida.

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Molecule (6/13)



  1. More data at CERN seems to hint at a new, very heavy fundamental particle beyond the standard model of quantum mechanics. Its mass is 750 GeV/c^2. For comparison, the top quark -- the most massive fundamental particle in the standard model -- has a mass of 173 GeV/c^2. See link: http://blog.physicsworld.com/2016/03/18/new-boson-buzz-intensifies-at-cern-fire-prevention-in-space-and-neil-turok-on-a-bright-future-for-physics/ I read somewhere that some physicists are proposing that dark matter is made of not yet detected heavy neutrinos. Could this be it? (I didn't see any electric charge data on the possible new CERN particle.)
  2. Article suggests the LIGO black hole pair may have been produced by a single collapsing star. It says "if the star were spinning very rapidly, its core might stretch into a dumbbell shape and fragment into two clumps, each forming its own black hole." So cool! Link: http://phys.org/news/2016-02-ligo-twin-black-holes-born.html
  3. "Space is different for different observers. Time is different for different observers. Spacetime is the same for everyone." - E. F. Taylor and J. A. Wheeler To answer SimplyCurious, I also wondered what connects time and space into spacetime. Then I learned about the "spacetime interval." Its a little involved, but I know of no better way to understand the connection. 1) Imagine you are seated in a classroom with other students. One student claps their hands together once. A little later, a second student also claps their hand together once. Say you and the other students measure the distance between hand-claps. We call this distance the "space interval." Assuming you all have the same measuring devices and methods, you get the same value for this distance or space interval. We call the elapsed time between the two hand-claps the "time interval." Using the same devices and methods, you and the other students also measure the same elapsed time or time interval between the two hand-claps. You all get the same values for the space and time intervals because you are all at rest with respect to each other. 2) Now imagine astronaut Laura flies in a rocket past the classroom at half the speed of light, relative to the classroom. According to special relativity, Laura measures a different value than the you for the time interval between the hand-claps. She also measures a different value than you for the space interval between the hand claps. Why? Because Laura is moving relative to you. Space and time are relative -- they are affected by relative motion. 3) Now you multiply the value you got for space interval by itself to get the square of the space interval. And you multiply the value for the time interval by itself to get the square of the time interval. Then you take the difference between the two squares. This difference is called the square of the "spacetime interval." The formula for the spacetime interval is: (the spacetime interval squared) equals (the time interval squared) minus (the space interval squared) Astronaut Laura also squares the value she got for the space and time intervals, and calculates the difference. This is her spacetime interval squared. You get together with Laura and compare calculations. You find you have measured different space intervals, and different time intervals, but have come up with the same spacetime interval. Space and time are relative -- they are both affected by relative motion. But spacetime -- as represented by the spacetime interval -- is absolute. It is not affected by (uniform) motion. Space and time are inextricably linked. We call this connection "spacetime". 4) Where does the spacetime interval formula come from? It is derived from Einstein's light postulate -- the speed of light is absolute or unaffected by relative (uniform) motion. The absolute nature of the speed of light leads to the Lorentz transform, the relativity of space and time, and to absolute spacetime. The above is based on the explaination in Einstein Relatively Simple
  4. As a start, you could try my book, Einstein Relatively Simple. It presents a concept-based explanation of special and general relativity for the non-expert.
  5. Scientific American blog says Earth is still getting hotter but not at the same rate. Per the article, the slowdown is caused by "the timing of two large ocean cycles, known as the Pacific multidecadal oscillation and the Atlantic multidecadal oscillation." This slowdown is predicted to end in the next few decades. If true, this is good and bad news. Good news because it gives us more time to put carbon-free energy sources in place before the worst of global warming hits us. Bad news because it could be an excuse to slow carbon reduction actions and give deniers more fuel (no pun intended) to argue against global warming. Link: http://blogs.scientificamerican.com/observations/2015/02/26/the-pause-in-global-warming-is-finally-explained/
  6. Kelnad - Link to a nice animated explanation for black holes from NASA (also has virtual trip to black hole): http://hubblesite.org/explore_astronomy/black_holes/
  7. I agree -- the "other universe" idea is speculation, no matter which idea you are talking about. But I don't agree that it is of no importance. For one thing, maybe in the future a scientist will detect evidence for another universe. And the idea of many universes may have profound implications on the origin of our universe and why our universe is so remarkably fine-tuned for life as we know it. Its pure speculation at this point, but fun to think about. And a number of physicists are working hard to develop theories and possible tests for the idea of multiple universes.
  8. According to astrology, I'm supposed to be a Gemini because of when I was born. This is supposed to mean that the Sun was in Gemini on my birth date. I guess this means that the constellation Gemini was behind the Sun on that date (at noon?). Anyway, this is wrong. Astrology charts are based on how the heavens were some 2000 years ago. Positions of stars and constellations have moved relative to Earth since the charts were generated. We are now in the Age of Aquarius. I would have been a Gemini had I been born 2000 years ago, but I'm not a Gemini now. Similarly, your so-called birth sign is not necessarily what the charts tell you either. So as far as I can see, astrology doesn't even keep up with changes to the positions of stars and constellations over time. Pseudoscience indeed.
  9. It's been suggested that the laws of physics emerged as our universe cooled from the big bang. John Archibald Wheeler wrote: "The laws of physics did not exist a priori, but merged from the chaos of the quantum big bang.'" I read that string theory has some 10^500 solutions, each giving rise to different physical features. Some physicists suggest each string theory solution represents a different universe in a multiverse of universes. So there would be all these universes; each with different laws of physics. And ours just happens to have the physical features which allow stars, galaxies, planets, and life as we know it to exist. So if there are really a humongous number of universes out there, each with its own laws of physics and physical features, what could they have in common? The only thing I can come up with is: logic. I mean even if there are multiple universes where the laws of physics are different, each set of laws presumably work within a logical framework for each universe. Without logic, there would be no laws of physics (and no mathematics to represent how these laws work). So here's my question, one which has been kind of bugging me since I was 16 years old: Why is the universe (or multiverse) logical?
  10. The BICEP2/Planck joint analysis is out. Evidence for "B-mode" polarized light in the Cosmic Microwave Background NOT confirmed. Too much interstellar dust in our galaxy - which can produce the same effect. Too bad. I don't know if there is a way around this dust problem with future instruments. (As I understand it, inflation -- the extreme expansion of the very early universe -- is theorized to produced gravitational waves. These in turn would produce a swirling B-mode polarization in the Cosmic Microwave Background. This is what the BICEP2 telescope in the South Pole was looking for.) Link: http://www.esa.int/Our_Activities/Space_Science/Planck/Planck_gravitational_waves_remain_elusive
  11. As of today, there is no compelling evidence for string theory (or M theory) or any quantum gravity theory. They are all speculation.
  12. Came across an article on yet another interpretation of quantum mechanics. It proposes that our universe is "Newtonian" but interactions with other universes causes the quantum effects we observe. I don't think this theory gives any new predictions that can be tested. Link: http://motherboard.vice.com/read/parallel-universes-colliding-could-explain-quantum-weirdness?utm_source=mbfb
  13. Thanks, Nicholas, for getting my book, Einstein Relatively Simple . I'm glad you found it understandable. As to Hawking's perspective, I advise caution. It is based on string theory which is speculation at this point. It has no compelling evidence to support it and is notoriously difficult to test. It may or may not have anything to do with reality.
  14. In a recent blog (Here's that cat again), Swansont gave a link to a visualization of the double slit experiment. He pointed out that "the depiction of electrons in classical trajectories detracts from" the depiction. I agree. The best depiction I have seen is in the link below (Quantum Wave Interference): http://phet.colorado.edu/en/simulation/quantum-wave-interference It shows the electron (or photon or atom, etc.) as a wave (wave function) passing through both slits, producing two waves which interfere with each other, and then the detection of a single particle on the detector screen. Each time the simulation is run, the single particle shows up at another random location on the screen, the probability of its location determined by the wave function (squared). Over time, the individual particles at the detector screen build up to form an interference pattern. It is a little more complicated that the depiction criticized by Swansont in his blog, but I think it is a much better aid in understanding quantum mechanics.
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