X-Rays

[mtessler]

I read the other day I could ask anything astronomy related so here goes.
Regarding X-Rays, it was my understanding they are very short lived, and that's why they are (relatively) safe to use for medical purposes. However, if they do have short lives, how do they last long enough to reach us here so we can view them (Spitzer Telescope)?
Are there different types of X-Rays that make this possible?
Thanks in advance for helping with this. I've asked a couple doctors but they didn't know enough about X-Rays to answer.

[rstevenson]

I'm not quite sure where you got the idea that X-rays are short lived. X-rays are just one part of the spectrum of radiation. Visible light is another part, infrared another, and so on. So X-rays can last as long as visble light or any other radiation as they travel through space. Therfore we can "see" the X-rays emitted long ago by various phenomena in the universe.

Rob

[neufer]

[b][color=#0000FF]Illustration of the relative abilities of three different types of ionizing radiation to penetrate solid matter. Alpha particles (α) are stopped by a sheet of paper, while beta particles (β) are stopped by an aluminium plate. Gamma radiation (γ) is dampened when it penetrates lead.[/color][/b]

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Regarding X-Rays, it was my understanding they are very short lived, and that's why they are (relatively) safe to use for medical purposes. However, if they do have short lives, how do they last long enough to reach us here so we can view them (Spitzer Telescope)?

"Excited" atoms that emit alpha particles (α), beta particles (β) and Gamma (γ) (or many other forms of "light") radiation may themselves be very short lived but the simple forms of radiation that they emit are extremely long lived unless that radiation just happens to run into something.

[geckzilla]

And no light ever spontaneously dies at some point after it is emitted. X-rays are just light your eyes can't see. If any light suddenly stopped randomly we wouldn't be able to see anything. It'd be weird and wouldn't make sense.

Ugh, gamma radiation is scary.

[Chris Peterson]

I read the other day I could ask anything astronomy related so here goes.
Regarding X-Rays, it was my understanding they are very short lived, and that's why they are (relatively) safe to use for medical purposes. However, if they do have short lives, how do they last long enough to reach us here so we can view them (Spitzer Telescope)?
Are there different types of X-Rays that make this possible?
Thanks in advance for helping with this. I've asked a couple doctors but they didn't know enough about X-Rays to answer.

To amplify on the other answers, x-rays (gamma radiation) are made up of photons. Photons don't have a lifetime, they last until something absorbs them.

Medically, x-rays are usually produced by an electronic tube, so you only have them while the power is on. They don't make what they hit radioactive, so their application is highly controlled. Gamma rays (as well as alpha and beta rays) can be produced by radioactive materials, and the amount and duration of that radiation is determined by the half-life of the parent, which (in a medical context) can be anything from hours to months (and outside of medicine, anything from a fraction of a second to billions of years).

Astronomically, x-rays can be produced thermally, by very hot gas, or electronically, by the motion of electrons in magnetic fields.

[geckzilla]

Chris, why do you say alpha and beta rays? Is that kind of a misnomer?

[neufer]

And no light ever spontaneously dies at some point after it is emitted.

Light can, however, spontaneously polarize at some "point in time" after it is emitted:

1.7 Quantum Theory: Wolff's Explanation of the Einstein, Podolsky, Rosen (EPR) Experiment & Further Predictions
'The Ultimate Paradox - Bell's Theorem' by Milo Wolff, Exploring the Physics of the Unknown Universe, 1994

[b][color=#0000FF][size=150]Experiment to test Bell's theorem:[/size] Polarized photons are emitted at the center, pass through the adjustable polarization filters on the left and right, and enter detectors on each side. Coincidences are recorded and plotted as a function of the angular difference between the two settings of the polarization filters.[/color][/b]

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<<In l935, Albert Einstein, Podolsky, and Rosen (EPR) put forward a gedanken (thought) experiment whose outcome they thought was certain to show that there existed natural phenomena that quantum theory could not account for. The experiment was based on the concept that two events cannot influence each other if the distance between them is greater than the distance light could travel in the time available. In other words, only local events inside the light sphere can influence one another.

Their experimental concept was later used by John Bell (1964) to frame a theorem which showed that either the statistical predictions of quantum theory or the Principle of Local Events is incorrect. It did not say which one was false but only that both cannot be true, although it was clear that Albert Einstein expected The Principle to be affirmed.

When later experiments (Clauser & Freedman 1972; Aspect, Dalibard, and Roger, 1982; and others) confirmed that quantum theory was correct, the conclusion was startling. The Principle of Local Events failed, forcing us to recognize that the world is not the way it appears.>>

[neufer]

Chris, why do you say alpha and beta rays? Is that kind of a misnomer?

It's an indication of Chris's age.

[Chris Peterson]

Chris, why do you say alpha and beta rays? Is that kind of a misnomer?

"Particle" is better, but historically the term "rays" has also been used, and I was just trying to keep the terminology consistent with "gamma rays".

I'm not sure I saw it stated explicitly here, so:

gamma rays (or radiation, or particles) are high energy photons;
beta particles (or radiation, or rays) are high energy (fast) electrons or positrons;
alpha particles (or radiation, or rays) are [usually] high energy (fast) helium nucleuses, i.e. a pair of neutrons and a pair of protons.

[geckzilla]

Yeah, I'm having a hard time thinking of photons as particles. That's my problem. Then again, being good at quantum physics has to qualify one as some kind of magical superhuman. Despite whatever delusions of grandeur I may occasionally have, I'm definitely not one of those.

[Chris Peterson]

Yeah, I'm having a hard time thinking of photons as particles. That's my problem. Then again, being good at quantum physics has to qualify one as some kind of magical superhuman. Despite whatever delusions of grandeur I may occasionally have, I'm definitely not one of those.

Being "good" at quantum mechanics simply requires being competent with mathematics. QM tends to be counterintuitive, but you need not be superhuman to develop intuition in that area, it just takes practice. If you worked with QM regularly, the oddness would become natural.

[neufer]

If you worked with QM regularly, the oddness would become natural.

• No it wouldn't.

[mtessler]

Thanks to all for the replies. It is true you can ask anything (astronomy related) here, and some very smart minds will answer. I appreciate it.

Seems it also spurs debate, which is also a good thing.

[Chris Peterson]

If you worked with QM regularly, the oddness would become natural.

• No it wouldn't.

Well, for anybody still young enough that their brain isn't a fossil. I should have been more clear.

[geckzilla]

Oh snap.

[neufer]

If you worked with QM regularly, the oddness would become natural.

• No it wouldn't.

Well, for anybody still young enough that their brain isn't a fossil. I should have been more clear.

[Beyond]

If you worked with QM regularly, the oddness would become natural.

• No it wouldn't.

I have to side with neufer on this one.
I've become naturally odd and i don't work with QM (or mathematics).
Of course, it may just be an effect of Beyonder Land.

[Chris Peterson]

I have to side with neufer on this one.
I've become naturally odd and i don't work with QM (or mathematics).
Of course, it may just be an effect of Beyonder Land. :lol:

If you're naturally odd, you might well find QM perfectly intuitive! We're talking about a branch of physics that might have been designed by Lewis Carroll, after all.

[Beyond]

I have to side with neufer on this one.
I've become naturally odd and i don't work with QM (or mathematics).
Of course, it may just be an effect of Beyonder Land.

If you're naturally odd, you might well find QM perfectly intuitive! We're talking about a branch of physics that might have been designed by Lewis Carroll, after all.

Lewis Carroll Oh, you mean Charles Lutwidge Dodgson. Sorry, never heard of him. Although i might have seen one or two things on TV that he did under his pen name.
But then, who ever pays attention to the credits
And besides, Beyonder Land goes beyond such confusing dribble as Quantum Mechanics.

[neufer]

I have to side with neufer on this one.
I've become naturally odd and i don't work with QM (or mathematics).
Of course, it may just be an effect of Beyonder Land.

If you're naturally odd, you might well find QM perfectly intuitive!
We're talking about a branch of physics that might have been designed by Lewis Carroll, after all.

<<The eponymous character of Mr Tompkins appears in a series of four books by the physicist George Gamow in which he aims to explain modern scientific theories to a popular audience.

George Gamow, Mr Tompkins in Wonderland (1940)
George Gamow, Mr Tompkins explores the atom (1944)

The books are structured as a series of dreams in which Mr Tompkins enters alternate worlds where the physical constants have radically different values from those they have in the real world. This results in the counterintuitive results of the theory of relativity and quantum mechanics becoming obvious in everyday life.

Mr Tompkins' adventures begin when he chooses to spend the afternoon of a day's holiday attending a lecture on the theory of relativity. The lecture proves less comprehensible than he had hoped and he drifts off to sleep and enters a dream world in which the speed of light is a mere 30 miles an hour. This becomes apparent to him through the fact that passing cyclists are subject to a noticeable Lorentz-Fitzgerald contraction.

Despite this inauspicious beginning to his scientific education, Mr Tompkins becomes acquainted with the Professor delivering the lectures and ultimately marries the Professor's daughter, Maud. Later chapters in the books deal with atomic structure (Mr Tompkins spends time as a conduction electron, returning to consciousness when he is annihilated in an encounter with a positron) and thermodynamics (the Professor expounds an analogy between the second law of thermodynamics and the bias towards the casino in gambling before being confounded by a local reversal of the second law through the intervention of Maxwell's demon who has introduced himself to Maud in one of her dreams).

Later books in the series tackled biology (a subject taken up by the son of Mr and Mrs Tompkins who has inherited the Professor's academic leanings) and advanced cosmology. In 2010 the first volume of a proposed ten-issue comic book series, The Adventures of Mr. Tompkins, was created by Igor Gamow, George Gamow's son, and illustrator Scorpio Steele. In the book Tompkins learns about relativity from Albert Einstein, radioactivity from Marie Curie and the structure of the atom from Ernest Rutherford. A second volume, in which Tompkins meets Charles Darwin, Gregor Mendel and James D. Watson, was published in July 2011.>>

[neufer]

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<<Kenneth Geddes Wilson (June 8, 1936 – June 15, 2013) was an American theoretical physicist and Nobel Prize winner.

As an undergraduate at Harvard, he was a Putnam Fellow. He earned his PhD from Caltech in 1961, studying under Murray Gell-Mann.

He joined Cornell University in 1963 in the Department of Physics as a junior faculty member, becoming a full professor in 1970. He also did research at SLAC during this period. In 1974, he became the James A. Weeks Professor of Physics at Cornell. He was a co-winner of the Wolf Prize in physics in 1980, together with Michael E. Fisher and Leo Kadanoff. He was awarded the 1982 Nobel Prize in Physics for his seminal approach, combining quantum field theory and the statistical theory of critical phenomena of second-order phase transitions, i.e., for his constructive theory of the renormalization group.

In this theory, he not only gave important insights into the field of critical statics and dynamics in statistical physics, but also indirectly helped to answer fundamental questions on the nature of quantum field theory and the operator product expansion and the physical meaning of the renormalization group. He also gave a constructive answer to another important renormalization group problem from solid-state physics, the Kondo effect. Not least, he pioneered understanding of the confinement of quarks inside hadrons utilizing lattice gauge theory.>>