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2 Sep 11 5:08 AM · 13d ago · 1 post · 1 source · development 2 of 2
The same IAEA article was shared on Mastodon by user hkrn@mstdn.social, cross-linking to both the original source and the Hacker News discussion thread.
International Atomic Energy Agency (IAEA) Publisherandsoitis Hacker News submitter
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I've no idea if they still do it, or if this was an option open to the general public or if it was a special thing for our group, but once upon a time, in my early teens, I got to tour NIST's test reactor in Boulder, Colorado.At one point in the tour, they turned on the reactor, while we stood along the edges of the pool it was immersed in…
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The title (likely intentionally) is misleading, it should say "travelling faster than light in a medium". Nothing here travels faster than light in vacuum.BTW there are special types of telescopes used to observe gamma rays - they cannot see gamma ray directly but observe a flash of Cherenkov light of a cascade of charged particles created when…
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It took me a long time to develop an intuition for light and electromagnetic wave propagation, and I’m still working on it.Fundamentally, changes in the EM field propagate always with the speed of light in a vacuum, i.e., c (also known as the speed of causality). Single EM waves propagate with exactly this speed and they do not magically slow down…
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A fun fact about Cherenkov radiation is that research on making efficient Cherenkov detectors in the 1960s led to the development of optical principles still used to design illumination systems and solar concentrators today.The late professor Roland Winston worked on this problem and discovered a geometry that could concentrate the light from a…
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The article has a section about what it can be used for, but only mentions the uses of the IAEA.Of course I am biased because I work in the field, but the by far most wide reaching application of Cherenkov radiation is in the detection of high energy particles, particularly in astrophysics.- Imaging Atmospheric Cherenkov telescopes detect the…
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Cherenkov radiation is also a key mechanism behind ultra high energy cosmic ray (UHECR) detectors. UHECR are understood to be nuclei, not gamma rays. For ground based detectors, light tight water tanks are fitted with photo multipliers to capture the flash of cherenkov light even secondary particles pass through the water.Additionally, they can…
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Several comments here mention that nothings goes faster than light in a vacuum, which is right. But... Putting aside all considerations of causality, if a particle was to go faster than light, it would also emit a vacuum Cherenkov radiation, as this particle would go faster than light. That would be a kind of supersonic bang. Some theories about…
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> How can something travel faster than light?> Nothing can travel faster than the speed of light in a vacuum. However, in other mediums, particles can potentially move faster than light. For instance, while in water, light would instantly slow down to 75% of its normal speed, but there are other particles that don’t slow down as much and end up…
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To be precise, what we call the “speed of light” is the limiting speed at which information and causal effects can propagate through spacetime. In vacuum, it coincides with the propagation speed of photons, i.e. of light. In other media or under certain conditions, however, light can propagate at a speed lower than , without changing the…
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Maybe the coolest (heh) application of Cherenkov radiation is neutrino telescopes like IceCube, detecting tiny flashes of light in cubic kilometers of ultra-clear Antarctic ice caused by vanishingly rare interactions between neutrinos and ordinary matter – and to exclude non-neutrino interactions, they look down, using the entire Earth as a shield…
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Yeah, but what is a medium? Every material is basically empty space with an atom here and there. So there is not a hard boundary for a particle to instantaneously slow down from speed of light in the air to speed of light in water. Some of them will travel a bit deep before hitting their first H or O or electron, or some salt ion. Anyway, it won't…
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A general rule of thumb is that if something is glowing blue or has a blue halo around it, you should run in the opposite direction.Unless you saw it from really close, in which case it's too late and you should probably relax, sit down, have a drink, call your loved ones...
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How is it possible for particles (with mass) to exceed the speed of (massless) photons in a medium?I don’t mean in terms of the speed of light in a vacuum. Just seems weird that something with mass could outpace something without… Why are the photons so slow?
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Not just gamma rays, cosmic rays too, although they filter the UV and are targeting nitrogen fluorescence and catch the cerenkov overlap. I’m sure there’s many people here who have worked on them.I worked on HiRes/Telescope Array in Utah (Not CTA).
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Your comment is a good reminder of why I love the HN community so much. Having acccess to knowledge in specific domains, like in this case, is truly a gem.And thanks!
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It's funny because I was reading about Cherenkov radiation just yesterday and the same statement was made (although with a proper clarification afterwards).
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>> The title (likely intentionally) is misleading,That is because that is not the title...the title is: "What is Cherenkov Radiation?"
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Can Cherenkov radiation carry information? If it can does this mean information can travel faster than light? Question from a physics newbie
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I wonder if there could be something other than vacuum, in which light would travel faster.
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