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You seem to have missed the bit that said: "unless the photons scatter off of something (e.g. dust)." When you see a laser beam projected into the sky, you are seeing the light reflected by dust and water particles in the air.

After London tapwater is bottled, the water is "premium tasting water accessible to everyone." How could premium tasting water not be worth a premium price? It's also "purified and enhanced with minerals" for designer limescale in my kettle rather than the plebeian limescale I get from tapwater. Importing a bottle from America is on my bucket list. Strangely, it's not on sale in London. [Later] Seems it's not bottled in Sidcup any more. https://en.wikipedia.org/wiki/Dasani Perhaps it should be the very last item on my bucket list.

...and they say he's not a politician...

My toes curl in their shoes... This is so utterly confused! Just read carefully, I cite, and emphasise: it occupies one unique set of coordinates" (only one time coordinate for one's current location in spacetime) But at a previous location it was another time coordinate, so another unique set of coordinates. Both are points on the world line on the spacetime map. Slowly I have the feeling I am debating the colour of a rose with somebody who is red/green colour blind, but denying that that is the case, and says that the flower and the rest of the plant have the same colour.

Yes, you could run the maths on it, though potentially this isn’t a straightforward calculation (especially in the case of the Alcubierre metric). My understanding (though I’m no expert on this particular solution) is that there is no horizon, but a narrow region of extreme tidal gravity. The two regions remain causally connected though. Again, I don’t know the answers to this straight off the bat, but of course one could sit down and do the actual maths (definitely not a trivial calculation!). The relationship between clocks here would be well defined, and can be calculated. My intuition is that causality would remain preserved in all cases that are actually physically realisable (and there is a big question mark in that regard, so far as the Alcubierre solution is concerned). Wormholes connect potentially distant regions in spacetime, so in principle they span intervals of both space and time. In principle, yes. “Now” is always a local notion - it would be very difficult, perhaps meaningless, to try and define a notion of simultaneity in a spacetime with a topology that is multiply connected. This is a very complex question, not just because this spacetime is multiply connected, but also because the existence of a wormhole does not necessarily imply causal connections (i.e. information may not be able to propagate through that wormhole, depending on its exact geometry). Interesting question though!

! Moderator Note OP, I am closing this thread and have removed your link. Members are welcome to post links, but they should not form the basis of your entire post. If you have something to discuss, please do so here rather than setting the expectation that others click through links to figure out what you're talking about.

Yeah, you're supposed to change them regularly due to that. They can only trap/block things. Distillation is probably the best single option but does depend on what contaminants you are hoping to remove.

I'm somebody who has done his undergrad in the east and has come to the west for grad. I'm questioning the choices made since as far as I can tell some are hard for me to understand for what I envisioned to be better and more established educational systems. I have also gotten mixed messages on how independent one should or should not be. I can and would prefer to be more independent. However, that does not seem possible within the current framework. In fact it makes it feel like a sisyphian task. I'm expected to be more independent but restrictions are placed such that I can't be. Maybe its more an issue with where I am currently specifically rather than the kind of system within this region in general. If you can't handle the heat, stay out of the kitchen. It's probably personal. A lot of students within the department have similar complaints about difficulty in things getting done. I don't think all of them have a poor balance but personally I do believe there are many.

Observers not in line with the laser will not see the photons, unless the photons scatter off of something (e.g. dust). The number of photons in the beam is large but not infinite (and can be found knowing the wavelength and power)

Too bad Bloomberg struggled in the debates...he just couldn't put his mouth where his money was...

Come on, people, stop polluting the planet's mental space once with a general theory of relativity! Interestingly, whenever anyone is asked publicly for opinions on drug addiction, homosexuality, pedophilia, or theory of relativity, everyone immediately knows everything about it, as if they were all addicts and gays and pedophiles and theoretical physicists. I know almost nothing about this because I am neither a drug addict nor a homosexual, nor a pedophile, nor a professor of physics. I first encountered the theory of relativity in high school and then I read about it and here I will explain how I understood it: Digging through the theoretical physics of his time, Einstein dug up "Lorentz transformations" and built "Special Theory of Relativity" on them. It turned out that this theory "holds the water", so in the rapture of success and based on his "happiest thought in life" that there is no gravity at all, he also launched the "General Theory of Relativity", which was embraced by the "popularizers of science" and who from theory made their "business". And as is usually the case, the inventor was often unaware of what he had actually found. In 1927, the famous physicist and philosopher Heisenberg, introduced to the world his "Theory of Uncertainty" as a natural law, claiming that we cannot simultaneously accurately measure the position and velocity of a particle, because it is a dynamic and statistical problem and because our methods of measurement are such that they simultaneously disturb the position and velocity of the measured particle. This ingenious and crystal clear idea was immediately accepted by most physicists, but not by Albert Einstein, because he could not accept the idea that something "could not" be done. Therefore, Einstein "pushed with all four" to disprove this theory, without even being aware that as early as 1915, with his "Special Theory of Relativity", he actually confirmed and supplemented the same theory, adding: that apart from being unable to accurately determine the position and velocity of a particle, likewise, when we are forced to do so (and always are!), we measure "with an error" equal to (1- (v/c)2)0.5 , depending on the relative velocity (v) of the inertial system in which we are measuring - AND THAT'S ALL! It would be foolish and unscientific to say that in an inertial system, depending on its velocity, units of mass, length and time change, and that objects, space and time deform depending on the direction and speed of the system. Soon, Einstein himself realized this, as well as the fact that his "General Theory of Relativity" was "nonsense squared" because it violated almost every law of physics. But why deny what is selling very well? Well, man has to live - from something! So every honor and glory to Mr. Einstein but save us God from all the "popularisers of science" and physics professors who don't know physics!

So after getting out of academia I must miss it... just after Christmas, this new year I was thinking about issues in cosmology and all this Dark Matter and Dark Energy theories, and had this crazy idea that's within Einstein's GR- maybe, but more so, it's within a non-flat curvature quantum theory, which we don't have so all this is speculation, but i thought perhaps tiny fluctuations in spacetime curvature (from moving masses in sub-atomic particles from distant parts of the universe), travelling in the same direction, in the same region of space, over billions of years, would interact and form very sharp curvatures in spacetime - on the scales 10e-18m to 10e-15m. The idea is that this would disrupt gravitation over the very long range. From this I think one can postulate 4 force effects, 3 gravitational and 1 radiation pressure. Two of the gravitational effects are a type of re-blooming of the gravitational potential, in fact the whole idea is really a type of localized gravitational potential by-pass and re-blooming effect, but not necessarily a quantized version gravity, still continuous just localized spacetime packets. I called it Fine Structured Spacetime (FiSS) because well - it would make matter FiZZ The thing is, at least to me, this idea seems to have an astounding potential to fix problems in cosmology. Every major problem I looked at, FiSS seemed introduced a force or effect that at least moved the problem in the right direction: it seems to explain Dark Matter, explain Dark Energy, rotation curves of galaxies, predicts a linear Tully Fisher relationship (although the math on this is a bit shaky, haven't done math now in 10 years as I'm out of the academic field), it's consistent with the bullet cluster, explains stability of spiral arms, barred galaxy structures, star formation in trailing gases for "Jellyfish Galaxies," weird ring galaxies like Hoag's object, partly resolves the "vacuum catastrophe" problem, possibly resolves the Hubble constant and the "Crisis in Cosmology," explains the "Cuspy-Core" problem, predicts the nature of voids, maybe explains "The Great Attractor" and "Dark Flow"... and it just goes on.. and on. I've probably just spent 3 weeks in cognitive bias looking for evidence for it, but I'm seeing it everywhere now... clearly I've lost all impartiality - I'm too invested in the idea, and that's when you need to step back and let others take a look and form their own option and give you some feedback. I wrote it up as manuscript and submitted to a few journals, a couple of weeks back, hoping to get a peer reviewer to look at it, but due to its early speculative nature, it was not accepted. Also sent the unpublished manuscript to a number of researchers in the field for some feedback, but they get bombarded with claims of solutions for Dark Matter, so I still haven't heard back from them. So I've decided to let it go, and just post the unpublished, un-peer reviewed manuscript on a few Physics and Astronomy forums, you can find the idea here: https://www.ecoonline.com.au/content/FiSS.pdf I'd love to get some feedback on it... anyone here that is intimately familiar with what's possible within a non-flat curvature quantum theory? Kind Regards Dr Gregory Grochola PS: yes I see there are lots of untrained people posting "theories", I'm well aware of the Scientific Method, you can check my track record as a scholar below, 20 of those papers I wrote myself over a period of 10 years... https://scholar.google.com/citations?user=aKhLFkwAAAAJ&hl=en FiSS.pdf