Wikipedia:Reference desk/Archives/Science/2018 June 24

= June 24 =

looking for news about some guy who dies due to using deodorant or perfume
I'm looking for news from many years ago (maybe 10-15 years ago) about a guy that died due to using of deodorant or perfume. In this news they explain that it's not healthy to use them because of that. I don't have any lead for these news. 93.126.116.89 (talk) 07:35, 24 June 2018 (UTC)
 * Jonathan Capewell or Daniel Huxley, mentioned in our List_of_unusual_deaths. Brandmeistertalk  09:42, 24 June 2018 (UTC)
 * No Huxley on that page. --76.69.47.228 (talk) 21:14, 24 June 2018 (UTC)
 * Because he was the second to die in that manner, so only the first is included. Brandmeistertalk  07:13, 25 June 2018 (UTC)
 * Remark that Capewell was not killed by the deodorant or perfume itself, but instead by the propellant (butane and propane) in the spray can. 194.174.76.21 (talk) 11:47, 25 June 2018 (UTC) Marco Pagliero Berlin
 * Yeah, hydrocarbon propellants are flammable, and cans using them usually contain warnings to this effect. Bach in the old days, they used Chlorofluorocarbon propellants, which I think are not flammable, (Halomethane was actually used as a fire-fighting agent) but these were phased out due to damaging the ozone layer Eliyohub (talk) 17:34, 25 June 2018 (UTC)
 * This is not really relevant, as Capewell was not burned but poisoned. According to Brandmeister's link above Capewell had 0.37 mg/l _each_ of butane and propane in his blood "whereas 0.1 mg per litre can be fatal". He apparently managed to spray his whole body from tip to toe, possibly several times in a day. 194.174.76.21 (talk) 10:37, 26 June 2018 (UTC) Marco Pagliero Berlin

Highest possible limit in nature
What accelerates the fastest particles in nature? Something that's moving below that speed?

And what is the highest possible frequency of an electromagnetic wave? Can a process cause a frequency higher than its own frequency? --Doroletho (talk) 12:24, 24 June 2018 (UTC)
 * Have you reviewed Electromagnetic radiation? ←Baseball Bugs What's up, Doc? carrots→ 12:58, 24 June 2018 (UTC)
 * Yep, but there's no hint of a frequency limit. --Doroletho (talk) 13:19, 24 June 2018 (UTC)


 * I'm not sure I understand your question. The sun gives off sunlight, which moves at, well, the speed of light while the sun itself moves at a much lower pace (it will depend on which POV you measure from, but it's much less than the speed of light). The highest frequency electromagnetic waves are classified as gamma rays; the article lists some sources, including thunderstorms here on earth. Matt Deres (talk) 13:32, 24 June 2018 (UTC)

The Speed of light 299,792,458 metres per second is a limit that particles cannot exceed so a particle's acceleration is described in terms of its energy or momentum, usually measured in electron volts (eV). Among Particle accelerators the Large Hadron Collider located underground near Geneva reaches a record 6.5 teraelectronvolts (TeV) per beam. Higher energy accelerators will require even larger curved tunnels due to the increased beam rigidity, see Particle accelerator.

The highest possible frequency of an electromagnetic wave is when its wavelength is in the vicinity of the Planck length, such as a Gamma ray of frequency 1020 Hz.

Can a process cause a frequency higher than its own frequency? Yes, when a single frequency (sinusoidal) signal is distorted by a non-linearity then harmonic component frequencies are produced at integer multiples of the input frequency, see Frequency multiplier. DroneB (talk) 13:35, 24 June 2018 (UTC)
 * Plank frequency is actually about 3 Hz, not 1020 Hz. Ruslik_ Zero  20:59, 24 June 2018 (UTC)


 * The OP may find information, and further links of interest, in our article on the Oh-My-God particle. {The poster formerly known as 87.81.230.195} 2.125.75.224 (talk) 21:11, 24 June 2018 (UTC)
 * Particles with rest mass not only can't exceed c, they can't even attain c, the speed of light in a vacuum, though they can get arbitrarily close. Photons always travel at c in a vacuum, and moreover all observers agree that they travel at c. This is one of the two fundamental premises of special relativity. There isn't anything that "accelerates" photons, because they always travel at c or, if traveling through a medium, slower. --47.146.63.87 (talk) 07:24, 26 June 2018 (UTC)
 * To be precise, special relativity doesn't say anything about photons, per se. It would be fine with SR if photons had positive rest mass and did not travel at exactly c.  The important thing is just that there be a finite c that all observers agree on.
 * I recall a Scientific American article that detailed how Maxwell's equations would have to be altered if photons were found to have positive rest mass. That was one I found in some ancient stacks in my high-school library.  I gather that things have moved on in the interim and that most physicists are convinced that the rest mass of the photon is exactly zero.  However that isn't necessary for special relativity. --Trovatore (talk) 03:57, 27 June 2018 (UTC)


 * Massless particles (photons) travel at exactly the speed of light, starting when they are created. But particles with mass cannot reach the speed of light, so it's not clear (to me) how to think about their acceleration. In particular, the neutrino is said to have mass. However, neutrinos thought to have been created in the heart of SN 1987A, 168,000 lightyears away, reached Earth slightly before the light did, (the light was delayed within the star by bouncing around, hitting matter.) This means that these neutrinos were moving at most a few parts per billion less than the speed of light. I don't know if we can say that the nuclear decay processes that created the particles "accelerated" them. -Arch dude (talk) 03:13, 27 June 2018 (UTC)

Our article Emission spectrum may be of interest - especially the Origins section. Richerman (talk) 14:25, 27 June 2018 (UTC)
 * see also Ultra-high-energy gamma ray and Very-high-energy gamma ray. High energy photons interacting with magnetic fields or other photons of any energy (including thermal radiation) can produce electron-positron pairs, so there will be a limit in nature. How fast something can accelerate may depend on how "hard" that which pushes the accelerating object is. Possibly a heavy nucleus is very hard, so nuclear reactions will give the fastest acceleration that humans can do. Graeme Bartlett (talk) 04:09, 30 June 2018 (UTC)

How fast would a lineac have to accelerate protons and nuclei to disintegrate them without collision?
The neutrons and down quarks would be left behind if the electromagnetic field was strong enough to overcome the strong force right? How hard would it be to actually build a lineac that can make an electromagnetic field strong enough to break nuclei or protons? Is it like something we could build (in space?) with $100 billion or $10 trillion or is it forbidden by the known laws of physics or somewhere in between? Sagittarian Milky Way (talk) 16:17, 24 June 2018 (UTC)
 * The process of accelerating a particle is inherently a type of collision, insofar as momentum and energy are imparted to the particle. A good article to start at would be scattering theory, which introduces some pretty heavy concepts.
 * The original question - "how fast ... could a particle accelerate ...without a collision..." is almost as meaningless as asking "how fast could a particle move if it wasn't moving?"
 * Sometimes, it's hard to put ideas about physics into words of the English language; but this is why physicists spend so many years in formal study, so that their terminology is standardized and so they can encapsulate complicated ideas in mathematical formulations that concisely and precisely summarize the statement. A really good introductory physics textbook might be worth your time, before you dive headfirst into theoretical limits that take a toll on simplification.
 * If you're looking for more palatable fare, here's last week's SLAC public lecture: The End of Spacetime
 * Nimur (talk) 19:27, 24 June 2018 (UTC)


 * The electromagnetic force must become larger than the QCD string tension. A charge particle that enters a strong electromagnetic field will accelerate, emit bremsstrahlung, and lose energy. This will happen long before the field has had a chance to build up to the required strength. So, you must consider a neutron which enters a region where there exists a strong field. You can e.g. consider an ultra high energy cosmic ray with a kinetic energy of, say ,$$10^{20}$$ eV in the form of a neutron that enters the magnetic field of a magnetar, see this article for details. Because the neutron has net zero charge, it won't get deflected by the magnetic field. However, the Lorentz force on the quarks becomes extremely large, so large that this will overcome the QCD string tension. This causes quark anti-quark pairs to be created forming pions, and these pions are ten subject to the extremely strong fields, causing more pions to be formed. Count Iblis (talk) 19:55, 24 June 2018 (UTC)
 * Neutron has a magnetic moment. So, it is deflected by an inhomogeneous magnetic field. Ruslik_ Zero 20:56, 24 June 2018 (UTC)


 * Continuing in the same vein as Nimur, Isaac Asimov's excellent history of the atomic theory and evolution of particle theory Atom is a painless way to ground (no pun intended) oneself in the concepts involved in the OP question, if anyone's interested. Not as useful to that specific question as the other answers above, but you might understand the answers better after reading Atom (it's not a long book, and not as dry as most physics textbooks are). loupgarous (talk) 02:47, 1 July 2018 (UTC)