Radiation Definition and 1000 Threads

First of all i tried to follow the textbook. Here they start of by modelling the atom as an harmonic oscilator: Then they find the solution as: They neglect the second term as omega_0 >> gamma which also makes good sense so they end up with: So far so good. After this they state the...

I am not sure of the answer. But I am guessing that infra-red rays carry more heat radiation than ultra-violet rays, and the heat is instantly felt on our skin when exposed to both these rays. So what we feel is the heat sensation from infra-red rays and that sensation is missing when it's...

MCNP Output: energy stopping power range radiation beta**2 density rad/col drange dyield n collision radiation total yield corr mev mev cm2/g mev cm2/g...

This is a topic that will be relevant for anyone who plans to use "realistic" artificial gravity (of the centrifugal kind, rather than the "acceleration-based" kind) in their stories - be it on spaceships or space stations: How much of the ring walls has to be dedicated to radiation shielding...

Alright, since I’m still stuck on my sci-fi story because I can’t exactly outline the mid-point plot twist with a realistic catastrophe on board an interstellar spaceship, I thought I’d widen the scope a little — towards full-on open brainstorming: What, if anything, can realistically go wrong...

The intense gravity near the event horizon causes complementary particles to pop into existence spontaneously. As local space-time is continuous through the EV, the same would be happening just inside the EV, only more so as the gravity field and gradient is greater. So near the singularity...

The Hawking radiation comes from a pair of complementary particles, an electron and a positron for example, coming into existence spontaneously near the event horizon as a result of the intense gravitational field. One particle gets captured by the Black Hole while the other escapes, taking a...

a. We know metals emit EM radiation upon heating or electric current. I'd like to understand more fundamentally how this phenomenon takes place, on the basis of the basis of band structure, and which electrons are involved ? b. Classically, charges emit radiation when accelarating or...

I came across an academic article by Mary Olson entitled "Disproportionate Impact of Radiation and Radiation Regulation" (https://www.tandfonline.com/doi/abs/10.1080/03080188.2019.1603864). Based on data in BEIR VII, she illustrates that women are more sensitive to ionizing radiation than men...

Hi all - I'm not a physics grad, my knowledge is limited to whatever I can glean from popular science publications. Anyway, I'm crafting a hard sci-fi story - 'hard' because it's written to seem kind of plausible, or at least not outrageously surreal - no shape-shifting or anti-gravity or...

Honestly, folks, I don't even know how to start. I included in the Relevant Equations section the relativistic generalization of the Larmor formula according to Jackson, because that's the equation for the power emitted by an accelerated particle, but I don't see how that gets me very far. The...

Hi, I'm trying to solve a problem involving radiation in a triangular cavity: As you can see, lengths and emissivities of all surfaces are given. For two of them, the heat flux is known and the temperature has to be found while for the remaining surface it's the other way around. I have the...

The "sleep hormone" melatonin, sold at health supplement stores, has been found to prevent radiation sickness from ionizing radiation: https://pubmed.ncbi.nlm.nih.gov/30073934/ There are also some other references for this findable with a Google search. But you don't want to be on melatonin...

C = sqrt(E/M)...this would suppose the ratio of the amount of energy vs. the amount of mass in the universe. If not, why not. If there is no mass, just energy, or much less mass at the moment of the hypothetical Big Bang, then, there C would be significantly higher, thus explaining cosmic...

Eye adapted to darkness is fairly sensitive to small numbers of photons. See for example the derivation here: Polaris, bright for a star, is estimated to send 100 000 visible photons per second into a dark adapted pupil. The rear wheels of Little Dipper are about 15 times dimmer, so about 6000...

As I've mentioned in a few previous threads, at the midpoint of my sci-fi story on a generation ship, I need a disaster that wipes out about a third of the (male half of) the crew. Several people have suggested things like "a virus that disproportionately affects men", but that didn't quite cut...

Hallo, I would like to display the RTE (Radiation Transport Equation) dimensionless. In the picture, the RTE is shown. I would like to have the Planck number (or N) inside at the end. Additionally, the Prandtl number and the Rayleigh number can be inside. I have already many attempts behind me...

Scientific American June 2, 2022 Vol 32 Number 6 Page 62 Title: Skin Cancer around the World Two Quotes: “The main cause of skin cancer is the exposure to the sun’s ultraviolet rays…” “UV radiation is about 40% stronger in New Zealand than it is at corresponding latitudes in the Northern...

How can a particle created just outside the event horizon with no velocity (?) escape a black hole, never to return, when black holes gravity is so strong that they can pull matter away from stars many kilometers distant?

Hi, I have some questions about cosmic microwave background radiation, CMB, and I thought it's better to ask them together. I have combined all related content for each question to make the question clearer, understandable, and to provide proper context for any person like who stumbles upon...

Hi, The following is my basic understanding of blackbody radiation spectrum. The important sections are in boldface. Source: https://en.wikipedia.org/wiki/Black-body_radiation#Spectrum Question 1: The quote above says that at room temperature (let's say 20 C or 293 K) the emission is in the...

hello i found this equation in a course about x rays , and i couldn't find it anywhere else they said that it is the theoretical expression of the energy spectrum , and dφ/dE is variation of the power emitted by the Coolidge tube as a function of the energy of the x ray. but i didn't understand...

I am calculating Responsivity of a pn junction photodiode (a.k.a the target) by irradiating radiation from LED sources. For this purpose, i have two LEDs, one UV and another green LED. Note that LEDs are placed close to the target.UV LED : Manufacturer has given total radiant power to be 20mW...

Does a single charged particle in free fall into a black hole radiate?

Solar radiation-: it is em radiation emitted by son. it is short wave radiation. it comes in many forms. 1) visible light 2) radio waves 3) infrared 4) x rays 5) uv rays Global radiation-: it is sum of direct and diffuse radiation arriving at a ground. What are the differences between these two?

The image above is the solution posted by the book. I can follow the reasoning that has been used, but i have a trouble particularly at the first equation itself. Why should $$n = 2 \rho / m_{H} $$ instead of $$n = \rho / (2m_{H})$$, since the mass os a molecule of hydrogen is two times the...

A little more clear: I'm looking for a video or animation where I can visualize/see radiation on space ice (Europa or the Galilean moons). I know that radiation is invisible, but what does the ice actually look like or how does it change visually when its bombarded with gamma rays? Because its...

Does every species get its own 5.5%-calibrated sievert? It's morbid to ask, I know, but given that Chernobyl is full of dogs I have to ask whether there is such a thing as a dog-sievert?

A DC supplied superconductive electric coil must give off EM radiation according to Maxwell's law because rotation is acceleration. Does it?

What is power of EMF radiation inside of electric cars? What is frequency range, ELF?

Going to smaller transistors with higher density increases sensitivity. This an issue in terrestrial systems as much as it is an issue in space. I've of issues with microprocessors in space having data issues, or chips like P5-133 having to be reset. Here are some interesting stories...

I am considering writing a story that features aliens indigenous to a planet orbiting a red dwarf star. Even so, because of its proximity to the red dwarf, the planet's surface receives much more radiation than Earth's surface does. What is more, the planet has no moon to stabilize its...

Hello, Einstein introduced stimulated emission (along with spontaneous emission and absorption) to derive Planck's radiation law using his A and B coefficients in his 1917 paper. My question is, is it possible to separate the Planck radiation spectrum into a fraction that is spontaneous...

Mass of a satellite is 750g(##m = \rho V = 8,96 \frac{g}{cm^3}\cdot (\frac{4\pi(100cm)^3}{3} -\frac{4\pi(99,9cm)^3}{3}) = \approx 750g =0,75kg##) I am not sure what to integrate. I solved T there but it seems far stretched $$T =\sqrt[4]{\frac{dQ}{dt}\frac{1}{e\sigma A}} $$ How to get the...

I have questions about Black body radiation. see the attached image 1). It explains that the Spectral radiance measurement of 7000K temperature is the same as both 300 and 520 nm wavelength light. See here both A and B shows 60. Is my understanding correct? 2). Is spectral radiance the number...

https://www.theregister.com/2021/11/15/wireless_information_transfer_with_fast_neutrons/ https://www.sciencedirect.com/science/article/pii/S0168900221009013 Not sure there are any practical uses, but interesting none the less...

I'm seeing 2-3K counts/minute background on my Ludlum Model 3 Survey Meter. Are we having above normal rates lately? Never mind, I was on the X0.1 scale. But that's still high, isn't it?

If I have a source of radioactivity that is concentrated instead of evenly spread out, like a "tablet" source instead of a evenly distributed aerosol/dust on ground for example then is it possible to even estimate the total number of disintegrations (Becquerels per second) by measuring the...

The image of the background radiation unlike galaxies and super galactic clusters are fixed through out time yes? Is this true only to a certain extent? Also can the radiation it self be used as a coordinate system since it's unchanging in our observable universe and presumingly fixed to the...

What are the most common types of cancer caused by exposure to excessive amounts of radiation?

Given that the magnetosphere plays a major role in protecting life here on Earth, how hazardous is the incoming space radiation at the poles? Here I mean at ground level, as opposed to being in an airplane. I'm thinking especially about solar flares, coronal mass ejections, and the like, but...

Electromagnetic radiation is propagating sinusoidal electric and magnetic fields. Are the peak amplitudes of these fields in any way related to the radiation's other parameters, e.g. its instensity?

General relativity tells us that an object in free-fall is actually inertial, following a geodesic through curved spacetime, and not accelerating. Instead, it's objects like us, on the surface of a large body, that are accelerating upwards. Maxwell's equations also tell us that accelerated...

Having had a look at the following video of the dipole antenna and the creation of EM radiation, which I completely understand, I had a look at the link http://hyperphysics.phy-astr.gsu.edu/hbase/Astro/procyc.html#c1 and the hydrogen fusion process within a star. Looking at the process how do...

Hello! If I place a particle with more energy levels (of the order of kT) in a well defined state, in a thermal bath at temperature T, how will the blackbody radiation affect the internal state of the particle i.e. will the distribution be classical or QM? Basically, if I prepare that particle...

Hi, I was reading about the pressure exerted by radiation and need help with few points. I'd appreciate if you could help me. Source: Proceedings of the American Academy of Arts and Sciences, Volume 38, By American Academy of Arts and Sciences , 1903 You can check this capture for more...

About 0.38 Myr after the Big Bang, the universe cooled to about 3,000 K and went through the recombination era. Electrons and protons combined to form neutral hydrogen atoms and the photons became free to travel through space. The freed photons can be considered as photon sources of a small...

I’m worried because my husband brought home a freezer bag size of blue fin tuna that his friend caught off of the Southern California coast, he cut some up and gave it to my husband. My husband put it in our kitchen freezer, I’m worried there’s radiation being emitted such as cesium 134 or...

I have been reading some material related to the thermal and non-thermal features of Hawking-Unruh radiation. It seems some authors label any radiation that emanates within curved spacetimes (including non-inertial frames) either as non-thermal or approximately thermal if it doesn't follow...