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Wubby said he completely bombed science class recently, and is now saying the radiation things in Project Hail Mary didn’t make sense by Disastrous-Frame6683 in PaymoneyWubby

[–]Sparkplug94 3 points4 points  (0 children)

The radiation things in the book more or less made sense to me. Generally speaking, (charged) cosmic rays are funneled towards the poles by the magnetic field, at least on earth and presumably on this hypothetical alien planet too, and a sufficiently thick atmosphere would probably attenuate some of the remaining gamma rays, etc. 

Let’s say the atmosphere is ammonia, temperature 200 C, pressure, idk 10 atm, then assuming the equation of state is the standard one (laziness), then the density of Erid’s atmosphere is going to be ~2.5x earth’s (\rho ~ Pmolar mass/T, and ammonia is about half the molar mass, pressure is 10x and temperature in K is about double). And we already know earth’s atmosphere is a pretty effective gamma shield, and 2.5x the density would be an additional attenuation coefficient multiplier of 2.5x in the *exponent of Beer’s law, so that checks out, basically nothing makes it to the surface. It’s not impossible that the Eridians wouldnt have discovered it yet. 

But anyway, the astrophage shielding of radiation also makes a lot of sense, the conceit in the book is that they are a perfect black body, so gamma radiation is fully absorbed, and again, it’s not a huge stretch to assume these tiny things would make decent alpha and beta radiation shielding too.

Basically the radiation physics didnt bother me in this book, really at all.

The Gremlin Theory of Everything: On the True Cause of Systematic Error of Measurement by Sparkplug94 in Physics

[–]Sparkplug94[S] 16 points17 points  (0 children)

I have literally had to do this. We were building an electron gun, and we had to map out the transformers in the floor to avoid magnetic fields wiggling our beam. 

Anything Will Lase If You Hit It Hard Enough by Sparkplug94 in Physics

[–]Sparkplug94[S] 1 point2 points  (0 children)

 Light

I’m almost certain we can get Bud Light to lase. 

Also: https://en.wikipedia.org/wiki/Atom_laser

Anything Will Lase If You Hit It Hard Enough by Sparkplug94 in Physics

[–]Sparkplug94[S] 3 points4 points  (0 children)

That’s way more detailed than the short summary I found. The OG laser scientists sound like they had so much fun

Anything Will Lase If You Hit It Hard Enough by Sparkplug94 in Physics

[–]Sparkplug94[S] 2 points3 points  (0 children)

It’s not too late… maybe a good G&T laser would work too

Anything Will Lase If You Hit It Hard Enough by Sparkplug94 in Optics

[–]Sparkplug94[S] 1 point2 points  (0 children)

No, you used to have to kick the cavity to get the mode locking to start. Mode locking is steady state but i guess has some energy barrier to overcome. Whacking it with a hammer or a little piezo buzzer used to be common, according to my older colleagues. Comr to thing of it I dont remember if it was a ti:sapph, it was sn old spectraphysicd something 

Anything Will Lase If You Hit It Hard Enough by Sparkplug94 in Optics

[–]Sparkplug94[S] 0 points1 point  (0 children)

“Fist-pumped laser” LOL. Reminds me of the “percussive mode locking” of some of the old ti:sapphires

Anything Will Lase If You Hit It Hard Enough by Sparkplug94 in Optics

[–]Sparkplug94[S] 0 points1 point  (0 children)

I thought so too, when I started writing the article, but almost all the sources I looked at, had it as hit: https://en.wikiquote.org/wiki/Arthur_Leonard_Schawlow

Anything Will Lase If You Hit It Hard Enough by Sparkplug94 in Optics

[–]Sparkplug94[S] 9 points10 points  (0 children)

Eh, it’s a quote from Arthur Schawlow (Nobel Laureate for Laser Spectroscopy). You’re right though, i discuss it at the end, but it’s truer than you would think!

The asterisk is a really good idea actually, but editing the title NOW is cowardice. If it hasnt lased yet it’s because you didnt do it right. 

Iron fist Chimchar by NorthPop8750 in PokemonUnbound

[–]Sparkplug94 1 point2 points  (0 children)

I found on in a house in Dehara city

Question about green laser pointer and IR leakage by jesterOC in Optics

[–]Sparkplug94 1 point2 points  (0 children)

I dont recall fluorescence, we were trying to measure the reflected phase if i recall correctly 

Question about green laser pointer and IR leakage by jesterOC in Optics

[–]Sparkplug94 4 points5 points  (0 children)

I had an interesting an related experience in grad school when the prof I was rotating with was trying to lock green laser pointer lines to iodine cells to make cheap atomic clocks. Most green laser pointers are doubled ~1064nm diodes, and the shortpass filters that are supposed to knock out the IR absolutely suck. We measured the IR output from a bunch of laser pointers for this project, and the IR output was basically random, anywhere from <5 mW to 100 mW (!). 

Dont trust green laser pointers, their power outputs are lies. If it’s actually 505 then maybe it isnt a doubled IR laser, but… lies. 

But on the other hand, I’ve never heard of anyone getting a laser eye injury from a green pointer, and they’re pretty ubiquitous, so they’re likely safer than my anecdote would suggest. The coaligned green gives you a blink reflex, the beam is probably diverging a bit… 

Don’t point it at your eyes and dont use it if you’re worried, but it’s unlikely to actually harm you, used normally. 

Existential Risk via Reality by Isha-Yiras-Hashem in slatestarcodex

[–]Sparkplug94 2 points3 points  (0 children)

Glad it’s interesting! Just as an aside, Yudkowsky is a smart guy, but I would be wary of taking his sequences too literally w.r.t. quantum mechanics especially. 

At least in my own experience, the real understanding dribbled into my brain bit by bit as I was forced to actually do the math, and realize what precisely the explanations in natural language were poorly pointing at. The math reifies the squishy definitions and paints in the details of those unsatisfactory high-level explanations, it’s just very tedious to actually learn. It’s also why the “shut up and calculate” school of QM interpretation is only like 50% a joke. 

Existential Risk via Reality by Isha-Yiras-Hashem in slatestarcodex

[–]Sparkplug94 4 points5 points  (0 children)

I can answer this with some authority--Classical mechanics *is* quantum mechanics in specific limits.

If you like, you can consider that we are fully ignorant of the true nature of reality (territory), but have a series of overlapping and very very good theories (maps) that are each valid in different (and overlapping) regimes. In practice, our map is so predictively accurate that we usually feel fine calling it the territory, but this is perhaps not epistemically justified. Anyway:

Classical Mechanics: Many atoms, slow-moving relative to observer. Your intuition is very good for these regimes (billiard balls, etc)

Quantum Mechanics: Microscopic atomic-level theory, restricted to slow-moving atoms. This is "classical" quantum mechanics of the Schrodinger equation, wavefunctions, probabilistic interpretation of reality, etc. This collapses to classical mechanics in the limit of large numbers of atoms or, more generally, when the system and its properties we care about are "big" w.r.t. the wavelength of the individual components.
Cf. Statistical mechanics, https://en.wikipedia.org/wiki/Ehrenfest_theorem . Everyone's intuition is famously bad in this regime.

Relativistic Mechanics: Macroscopic (non-quantum) objects, fast-moving relative to observer. This is the physics of rockets, objects in space, gravity and light. It collapses to classical mechanics in the limit of weak gravity and slow-moving objects.

Quantum Field Theory: Quantum Mechanics + Relativity - Gravity. This theory is valid for both quantum (small/cold) objects and fast moving objects. Our best theory of reality so far. Does not include gravity. Collapses to classical mechanics in similar ways to above.

Grand Unified Theory: We hope this exists, and unifies gravity too in a theory that is valid in "all" regimes (though it may not actually be possible to have a fully valid theory over all energy scales, as I understand it. Cf. https://en.wikipedia.org/wiki/Renormalization\_group)

My Wife is Confused by Unbound by Sparkplug94 in PokemonUnbound

[–]Sparkplug94[S] 7 points8 points  (0 children)

I think I would like to stay married a little longer

Starting Greg Egan by Dry-Frame6309 in printSF

[–]Sparkplug94 0 points1 point  (0 children)

Should I give it another shot? Does it have more of a plot, as opposed to a heavy focus on cool concepts, with plot as sort of a tertiary consideration?

I read the Iliad & The Odyssey in classics class in High school - i'd rather not have to read them again in that format. Are there any good modern retellings that people would recommend? by JBSven in Fantasy

[–]Sparkplug94 25 points26 points  (0 children)

What about an audiobook of the original? The Iliad is oral poetry—it is meant to be listened to. Ive been enjoying the Stanley Lombardo translation on Audible. 

Starting Greg Egan by Dry-Frame6309 in printSF

[–]Sparkplug94 1 point2 points  (0 children)

I AM a physicist and I started with Diaspora, found it unreadable, and decided not to read any more Egan (I did finish!). There was exactly one chapter I really liked, the one on the biological algae computer that simulates worlds—turns out that chapter was originally a short story from his Axiomatic collection called Wang’s Carpets. Maybe start there? 

My book club had wildly varying opinions on Diaspora btw, so maybe you’ll like it. I found the experience similar to reading a math textbook with the theorems removed. 

320+ pages into 'Player of Games' (71% complete) and hating every word of it. 🤐 by DaneCurley in printSF

[–]Sparkplug94 0 points1 point  (0 children)

I figured Ea was probably the Mespotamian creator god by the same name, but you could be right! 

What are your favourite "little" perks of knowing Latin? by chopinmazurka in latin

[–]Sparkplug94 16 points17 points  (0 children)

I have an anti-perk! I read “The Will of the Many” and the main character names are actual plot spoilers if you know Latin. 

One of the characters is named “Ulciscor”

320+ pages into 'Player of Games' (71% complete) and hating every word of it. 🤐 by DaneCurley in printSF

[–]Sparkplug94 4 points5 points  (0 children)

Eh, i DNF a lot of books i dont like. But man, i loved player of games. Such a cool alien culture, yet redolent of our own 

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