# IM Egdall

Senior Members

591

1. ## New Fundamental Particle Found?

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. ## Gravitational Waves Discovery Expected

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. ## Why was the idea of space-time created?

"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. ## Relativity For Dumbies

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. ## "Pause" in global warming explained

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. ## Black Holes

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. ## Parallel Universes Theory

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. ## is astrology really a pseudoscience? [yes]

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. ## Parallel Universes Theory

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. ## BICEP2 Evidence for Inflation NOT

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. ## What Is The Mechanism of Space Expansion?

Excellent posts here!
12. ## Higgs Boson and M-Theory

As of today, there is no compelling evidence for string theory (or M theory) or any quantum gravity theory. They are all speculation.
13. ## Science based on evidence

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
14. ## Blacks Holes? yes/no?

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.
15. ## Better double slit depiction

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.
16. ## Blacks Holes? yes/no?

I don't know about this "ripping of spacetime" in a black hole. As others have pointed out, the singularity is a place-holder for we don't know. I don't think physicists consider it a real physical thing. It is just that the equations of general relativity fail at that point.
17. ## First Teleportation of Two Quantum Properties

I know, imatfaal. As I understand it, a particle is not actually teleported, it is its properties that are transferred to another particle, so the second particle now has identical properties as the original one had. That's why I talked about teleportation of quantum properties. But thanks for your comment - your explanation is clearer than mine was.
18. ## First Teleportation of Two Quantum Properties

Report says physicists in China have teleported two quantum properties of a photon for the first time. And they say that, in principle, their approach could work for other properties as well. So are we getting close to the teleportation of all quantum properties of a photon, or of an electron for that matter? And then entire atoms perhaps? I would imagine doing this is still way in the future. Still, it's amazing to think it may be possible. Link: https://medium.com/the-physics-arxiv-blog/first-teleportation-of-multiple-quantum-properties-of-a-single-photon-7c1e61598565
19. ## Beginning/End of the World - Discussion

1. The so-called singularity is where the big bang theory breaks down. At time zero, we get infinite density and infinite spacetime curvature (gravity). When you get infinity for answers it means the equations no longer work. The big bang is the best current scientific theory on the evolution of the universe. Its many predictions have been verified by observations. But no one knows what happened at time zero or what caused the big bang in the first place. 2. String theory may or may not be "valid". So far there is no compelling evidence supporting or rejecting its predictions. The theory is notoriously difficult to test. 3. Predictions as to how the universe will end are speculation. For one thing, they are based on how dark energy will behave in the future -- but we don't know what dark energy is. If dark energy continues to behave the same way in the future as it does now, the most likely fate of the universe is that it will continue to expand until it consists of enormous black holes surrounded by dead stars. This is when the universe is about a billion billion years old. For details, check out page 266 of my book, Einstein Relatively Simple. 4. I think there are planets going around other stars which can and do contain life, some even intelligent life. I base this on the fact that planets seem to be common around stars, there are several hundred billions stars in our galaxy, and there are at least several hundred billion galaxies in the visible universe. And this doesn't take into account the presumably vast number of galaxies and stars out there beyond the part of the universe we can see. Plus the universe may be infinite in extent. We may not be very close to star systems where other life has formed, but it seems to me they are bound to exist.
20. ## Rosetta - First ever spacecraft rendezvous with a comet

After ten years of flight, ESA's Rosetta spacecraft now flying alongside a comet. This is an amazing feat. I can't wait to see what we learn from this. http://annesastronomynews.com/rosetta-arrives-at-comet-destination/
21. ## New laser weapon works in fog rain

My guess is they send out a "probe" laser beam (or other EM wave?) at a wavelength that can transmit through fog, detect the return signal, examine it for how it's wavefront is distorted by the atmosphere, and then send the info to a deformable mirror which distorts to match the atmospheric error. The high-powered laser beam is reflected off this deformable mirror. This distorts the high-powered beam's wavefront so it cancels the errors in the atmosphere and arrives at the target as a concentrated beam. The entire process must be fast enough to accommodate the rapidly changing atmospheric distortions and spatially fine enough match the atmosphere's spatial changes. The question is, as always, what is the range of such a device. I suspect that is classified.
22. ## Science Not Settled

Just read another article in Wall Street Journal (WSJ) dissing global warming. http://online.wsj.com/articles/matt-ridley-whatever-happened-to-global-warming-1409872855 It basically says the pause in global warming over the past 15 years shows that climate scientists have been wrong and there is nothing to be alarmed about. Then I came to this forum and found the link above from Swansont which shows there really has not been a pause. It is very disturbing that the WSJ continues to publish editorials without telling its readers the whole story. We need someone who is an expert in this area to write to the WSJ and straighten them out. The public needs to know the truth.
23. ## Laniakea: Our home supercluster

Our Milky Way galaxy found to be in the outskirts of a great galaxy super cluster - it has been named Laniakea (immeasurable heaven in Hawaiian). It contains some 100,000 galaxies stretched over 520 mega-light-years. In the video above, the galaxies are lined up in great cosmic webs. I think this is a result of how dark matter forms. And where dark matter is densest, galaxies tend to form.
24. ## Definition of observing

To help me picture quantum mechanics, I like the simplified view that a particle travels like a wave and is detected (interacts) like a particle. For example, in the double-slit experiment: A single electron is emitted from an electron gun. It speads out and travels like a wave, passing through both slits. This probability wave reaches the bank of detectors. Then only a single detector detects (interacts with) the electron, like a particle. This is the so-called collapse of the wave function. Two more points: (1) Due to the Uncertainty Principle, we cannot simultaneously know both the exact location and velocity of this detected electron. This uncertainty means the detected electron is also a wave, but a localized one. (2) When a number of electrons are shot from the gun, an interference pattern forms at the bank of detectors. This implies that each electron wave passing through the two slits produces two waves which interfere with each other, resulting in the interference pattern we see.