Are we in an age of technological decline?

The Something Awful Forums > Discussion > Debate & Discussion > Are we in an age of technological decline?

Rye: Jun 20, 2010; by exmarx

silence_kit posted:

Most of the time discoveries in condensed matter physics have to actually matter to society to earn a Nobel. And in a lot of those cases, those contributions weren't fundamental physics advances, they were more like chemistry/material science advances, like with Charles Kao proposing the idea for fiber optics by recognizing that if you were to make glass very pure, it could be very transparent to infrared light. Or Shuji Nakamura perfecting the metamorphic epitaxial crystal growth of gallium nitride to enable efficient blue light-emitting diodes. I'm sure those in high physics scoffed and said that those scientists discovered no new physics when those awards were announced.

If you think "high physics" (whatever the hell that's supposed to mean) scoffs at advances in other disciplines, then surely you can find a high physicist expressing that opinion. I don't think you have any idea what you're talking about, though- physicists all over the world are working on groundbreaking research in nanotechnology, materials science, biophysics, and optics.

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Rye: Jun 20, 2010; by exmarx

silence_kit posted:

Why do you need relativity to understand imaging and how lasers work?

I realize that the following thing I'm about to point out is not totally relevant evidence, but Shuji Nakamura, the Nobel Prize winner I mentioned before, is often credited for demonstrating the first blue semiconductor laser. He has a Masters-level electrical engineering education and probably was never taught special relativity.

I'm studying physics, but at my school engineers take introductory mechanics and electromagnetism with physicists. We covered special relativity in both mechanics and electromagnetism, and if Nakamura had a graduate level electrical engineering degree I would be shocked if he hadn't taken an advanced class in electromagnetism. You need to use special relativity to understand how particles behave in electric and magnetic fields in different reference frames. He was most definitely taught special relativity.

Positron emission tomography (PET scanning) involves the collision of positrons and electrons, which annihilate each other and release energy in the form of photons. How much energy is released from the annihilation is calculated using a fundamental result of special relativity- (E/c)^{2[\super] = p[super]2[\super] + (mc)[super]2}.

How do you calculate the momentum of a laser? You use that same equation, and let m be zero (as photons have no mass).

Special relativity is extremely important, and its implications are used in a wide variety of fields.

# ¿ Jan 29, 2016 19:39

Rye: Jun 20, 2010; by exmarx

silence_kit posted:

It's like telling a structural engineer that he really needs to know ~~quantum mechanics~~ statics to be able to do his job well. [...] Or for a more extreme example, it's like telling biologists that all of their work hinges on the existence of ~~the Higgs Boson or some other fundamental particle that physicists spend their entire careers trying to find~~ cell theory.

Lasers carrying momentum/energy (and how much they carry) is a direct result of the theory of relativity. You need relativity to describe how a laser can have momentum, and how much energy it carries.

quote:

Huh, I actually had read that before but only to section 3. The most famous part of the paper is when he postulates stimulated emission and the A and B coefficients and shows that they allow you to get the blackbody spectrum when you treat the electromagnetic field and the ideal gas with those A and B coefficients as being in thermal equilibrium.

It looks like later in the paper he checks whether the gas with the A and B coefficients in thermal equilibrium with the electromagnetic field follows the Maxwell Boltzmann velocity distribution. He uses a coordinate transformation to a moving reference frame of a gas molecule in the argument and does name-drop relativity, but does the transformation in the limit of non-relativistic molecular speeds, or basically, where the theory of relativity isn't very important. Sorry, I'm not convinced that relativity is that important to stimulated emission or to the basic physics of a laser.

Special relativity is pretty important.

Are you Andrew Schlafly?

# ¿ Jan 31, 2016 06:21

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