For Questions That Don't Merit Their Own Thread

[K^2]

7 hours ago, AHHans said:

Well, the experiments that I was referring to were done at Cern and involved creating a significant amount of anti-hydrogen and then trying to figure out if it gets attracted or repelled in Earth's gravitational field.

I don't think anyone seriously expected antiparticles to have negative gravitational mass. We don't have a practical Quantum Gravity, but we've had parts of one ever since General Relativity was shown to be a mean field gauge theory in the late 50s. So we know things like what the Lagrangian for Quantum Gravity has to be, and we can do quantum physics in curved space-times, like particle physics inside of neutron stars (which is wild, by the way). Negative gravitational mass for antiparticles just isn't lining up with all of that. Not that it wasn't worth checking, because finding otherwise would be a good indicator that something else is going on in QG world, but the expectation has been for positive gravitational mass.

We do know that something that behaves like it has negative gravitational mass absolutely permeates this universe, so it's definitely something worth looking for. A particle with negative gravitational mass would be a great candidate for the dark energy, but there can be entirely different explanations as well.

And yeah, thinking that negative gravitational mass somehow creates paradoxes is as silly as thinking that negative charges create paradoxes. Charge radius of electron is the same as charge radius of positron. It's not something that has ever been a problem. Existence of negative gravitational mass would require that the equivalence principle is slightly corrected in that the inertial mass is equivalent to the absolute value of gravitational, but, I mean, it's already sort of understood that the way inertial mass is derived from field equations is an absolute value sort of quantity. So it's not really a problem.

The sticking point is that nothing in existing theory predicts anything having such properties, and yet the universe is expanding at an accelerated rate. So we'll need to sort it out. Whether the solution will be found to involve negative gravitational mass or just something that acts a lot like it at such global scale - we'll just have to see.

[JoeSchmuckatelli]

Without a better place for this - I stumbled upon a really good biopic of M. Curie.  Really enjoyed it and learned quite a bit about her. 

https://m.imdb.com/title/tt6017756/

Worth a look if you have reached the end of Netflix and somehow missed it 

 

Edited August 28, 2021 by JoeSchmuckatelli

[K^2]

2 hours ago, JoeSchmuckatelli said:

Without a better place for this - I stumbled upon a really good biopic of M. Curie.  Really enjoyed it and learned quite a bit about her. 

It is an absolutely fascinating story. The awards alone paint a picture. She was the first woman to receive a Nobel Prize, which was in Physics, and she followed it up by getting a second one in Chemistry, becoming the first person to get two, and remains one of two people to have Nobel Prizes in two different fields. Her husband, Pier, also has a Nobel Prize, which he got jointly with Marie, and one of their daughters, Irene, won a Nobel Prize in Chemistry. And that's just Nobel Prizes.

[JoeSchmuckatelli]

8 hours ago, K^2 said:

It is an absolutely fascinating story. The awards alone paint a picture. She was the first woman to receive a Nobel Prize, which was in Physics, and she followed it up by getting a second one in Chemistry, becoming the first person to get two, and remains one of two people to have Nobel Prizes in two different fields. Her husband, Pier, also has a Nobel Prize, which he got jointly with Marie, and one of their daughters, Irene, won a Nobel Prize in Chemistry. And that's just Nobel Prizes.

That was one of the most remarkable things to learn - I knew about her and P. Curie's awards - but to hear that her daughter won one too? 

Amazing family 

 

 

Edited August 28, 2021 by JoeSchmuckatelli

[Spacescifi]

Fun fact. Marie Curie likely died in the name of science, her husband too, based on cancer symptoms from radioactivity.

Science we know always comes at a price for the first ones who do not know what they are dealing with.

 

Learning the hard way through experiment tests... (experience too).

 

Daughter died of leukemia, which if my medical terminology is still intact is white blood cell cancer.

Edited August 28, 2021 by Spacescifi

[wumpus]

1 hour ago, Spacescifi said:

Fun fact. Marie Curie likely died in the name of science, her husband too, based on cancer symptoms from radioactivity.

Science we know always comes at a price for the first ones who do not know what they are dealing with.

Learning the hard way through experiment tests... (experience too).

Daughter died of leukemia, which if my medical terminology is still intact is white blood cell cancer.

Hubby didn't live long enough to get (or at least die from) cancer.  He was run over by a horse carriage.

[kerbiloid]

And Marie died from neglecting the safety measures. It was not wise to carry a radioactive flask on the neck, even if it's funny glowing in the dark.

Edited August 28, 2021 by kerbiloid

[mikegarrison]

Rosalind Franklin, whose x-ray crystallography was key to proving the double-helix shape of DNA, died of cancer at the age of 37. Was that in part because of all the x-rays she worked with? Nobody knows for sure. (Ovarian cancer is known to be relatively in prevalence among Ashkepedant Jews.)

[kerbiloid]

13 minutes ago, mikegarrison said:

Rosalind Franklin, whose x-ray crystallography was key to proving the double-helix shape of DNA, died of cancer at the age of 37. Was that in part because of all the x-rays she worked with? Nobody knows for sure. (Ovarian cancer is known to be relatively in prevalence among Ashkepedant Jews.)

Wearing the radium flask on the neck illustrates how much seriously the unknown radiation was taken into account at all.

Unlikely the other radioactive stuff in the lab was protected better.

As a result, we can see the "radium girls" (google, images) and other such consequences.

[mikegarrison]

10 minutes ago, kerbiloid said:

As a result, we can see the "radium girls" and other such consequences.

Radium girls were because the factory owners didn't give a sh*t about whether poor working class girls died in order for them to make their money. Just like the people who who worked in match factories and got "phossy jaw".

[kerbiloid]

18 minutes ago, mikegarrison said:

Radium girls were because the factory owners didn't give a sh*t about whether poor working class girls died in order for them to make their money. Just like the people who who worked in match factories and got "phossy jaw".

While the bourgeois were buying and using this stuff themselves:

Spoiler

 

This thing was at least understandable.
https://translate.google.com/translate?hl=&sl=ru&tl=en&u=https://ru.wikipedia.org/wiki/Блокадный_«светлячок»

Spoiler

 

Edited August 29, 2021 by kerbiloid

[mikegarrison]

Well yeah, I mean *initially* to most people it seemed pretty amazing. It glowed! It must be extra powerful! They really had no clue what ionizing radiation was or how it affected DNA. They didn't know what DNA was, even.

But the watch factory owners knew the stuff was dangerous, and they deliberately lied to the workers about it.

[JoeSchmuckatelli]

SMH - my earliest lesson about radiation came from my father's stories of the people who used to lick the brushes used for painting the radium lines on watches. He had a few from his grandfather. 

That movie and images like those kerbiloid posted absolutely slay me. 

[kerbiloid]

1 hour ago, mikegarrison said:

It glowed! It must be extra powerful!

The first idea they should have: "Let's spread it onto a mouse, then watch and laugh, how it's running and glowing in the dark."

A week later they should probably replace the mouse.

[DDE]

1 hour ago, kerbiloid said:

This thing was at least understandable.
https://translate.google.com/translate?hl=&sl=ru&tl=en&u=https://ru.wikipedia.org/wiki/Блокадный_«светлячок»

  Reveal hidden contents

 

Amusing how the Radium Institute came up with the supply of fluorescent by mopping its floors for stray radium.

That said, this same stuff now massively comtaminates a lot of bunkers in SpB suburbs.

[kerbiloid]

6 minutes ago, DDE said:

suburbs.

Night in Kupchino

Spoiler

 

[ARS]

So I got few things to ask... and it's about stealth, specifically radiation-absorbent material (RAM):

1. If RAM can reduce a radar-cross section of an object, does it also works when applied on non-stealth design? For instance, using RAM on 747 instead on B2, does it reduce 747 radar cross-section even though the 747's design is a non-stealth design?

2. Does the radar cross-section reduction effect is affected by the size of an object? Let's take an example, if there's a RAM that 100% absorbs any radiation emission (including all spectrum of radar), and apply it on independence day city killer mothership (or any other gigantic flying object), would that object invisible to radar? (even though it would be obviously visible to the naked eye)

[SOXBLOX]

1 hour ago, ARS said:

So I got few things to ask... and it's about stealth, specifically radiation-absorbent material (RAM):

1. If RAM can reduce a radar-cross section of an object, does it also works when applied on non-stealth design? For instance, using RAM on 747 instead on B2, does it reduce 747 radar cross-section even though the 747's design is a non-stealth design?

2. Does the radar cross-section reduction effect is affected by the size of an object? Let's take an example, if there's a RAM that 100% absorbs any radiation emission (including all spectrum of radar), and apply it on independence day city killer mothership (or any other gigantic flying object), would that object invisible to radar? (even though it would be obviously visible to the naked eye)

Applied to a 747 or something like that, I think it would, at best, shrink the range at which a transmitter could get a good radar return. It certainly wouldn't provide anywhere near full stealth.

And if there were a 100% absorbent coating, it would be invisible to radar. But that's if it's 100% absorbent at all angles and energies. However, I think it could still be detected, mostly because, to the receiver, it would be a notable blank spot in the sky.

All of this is pure speculation on my part, written while I'm half-asleep. Take it with a bucket or so of salt. 

[SOXBLOX]

Here's a relevant video.

 

 

Edited September 1, 2021 by SOXBLOX

[DDE]

3 hours ago, ARS said:

1. If RAM can reduce a radar-cross section of an object, does it also works when applied on non-stealth design? For instance, using RAM on 747 instead on B2, does it reduce 747 radar cross-section even though the 747's design is a non-stealth design?

That's the basis for many Gen 4++ designs: minor shape changes and addition of RAM in an attempt to curtail signature without drastically altering the airframe. I hear claims of at least a tenfold effect.

3 hours ago, ARS said:

2. Does the radar cross-section reduction effect is affected by the size of an object? Let's take an example, if there's a RAM that 100% absorbs any radiation emission (including all spectrum of radar), and apply it on independence day city killer mothership (or any other gigantic flying object), would that object invisible to radar? (even though it would be obviously visible to the naked eye)

Indirectly, but effectively very much. Radar detects particular reflective surfaces, and any larger object is going to have more of them. It might have a lower signature from certain angles and in certain frequencies, perhaps, but overall bigger = worse.

[DDE]

Alright, let's take this in a very grim direction.

Il-112V crash last months. Informal results of the investigation have come in.

https://www.kommersant.ru/doc/4966809

Aileron actuator cable melted due to high-temperature fire inside the wing, which started in the engine and apparently had spread out of the nacelle by the time the primary and secondary fire suppression systems went off.

Now, the article notes that typical civilain Il's have not two but six sets of fire extinguishers. However, if all of them are in the nacelles I'm not sure jow it would help.

So, what happened, what would be burning, and what would the design countermeasures be?

[ARS]

26 minutes ago, DDE said:

Now, the article notes that typical civilain Il's have not two but six sets of fire extinguishers. However, if all of them are in the nacelles I'm not sure jow it would help.

I doubt it'll help. Fire suppression system are usually mounted on the engine nacelle simply because that's the area that's more likely to catch fire and the inward air movement into the engine usually enough to put off any fire after the system is activated. If the aileron actuator cable melted but the fire has been put off before spreading too far, best case scenario, you can still glide away to land, but considering the circumstances of this crash, it's likely the pilot tried to turn back to land the plane, but only one aileron are functional, causing an uneven lift on one side and send the whole thing crashing down

[K^2]

18 minutes ago, DDE said:

Aileron actuator cable melted due to high-temperature fire inside the wing, which started in the engine and apparently had spread out of the nacelle by the time the primary and secondary fire suppression systems went off.

Yeah, I kind of thought aileron failure must've been part of it. The way it suddenly starts rolling like that, I suspect, the pilot was countering the engine on the opposite side, which couldn't be cut to lower throttle due to lack of altitude for a free glide. And asymmetrical thrust during critical engine failure does generate both yawing and rolling torques. At low speeds, you have to counter pretty close to limit of authority to keep the plane straight. The moment that aileron went, there wouldn't even be time to cut throttle, not that the outcome would likely be any different, given the aforementioned lack of altitude.

22 minutes ago, DDE said:

So, what happened, what would be burning, and what would the design countermeasures be?

I don't know if they mean that the fire actually spread, or just that the heat from the engine was cutting into the wing like a blow torch. You can do a lot of damage inside a plane with just really hot air being fed under pressure. Ideally there shouldn't be enough stuff to burn inside the wing to do anything other than electrical damage. Unless the fuel tanks rupture, of course, at which point you have a different sort of problem.

And as far as I understand, the general idea is just to have enough fire suppression in the engine to kill the fire before it does any of the above, rendering the engine inert. I know airliners usually have additional fire extinguishers in crew cabin, cargo hold, and even sometimes on key electrical systems, but I've never heard of any just peppered throughout wings or anything like that.

[kerbiloid]

2 hours ago, DDE said:

and what would the design countermeasures be?

Not the actuator cable, but the actuator pipe/bar/boom штанга, as I had read.

https://translate.google.com/translate?hl=&sl=ru&tl=en&u=https://www.rbc.ru/society/01/09/2021/612ec7529a79478f241ba52a

***

Probably, wires instead of mechanics
https://en.wikipedia.org/wiki/Fly-by-wire

The wires are soft, they can be curved and pass at several tricky routes, so at least one stays intact in case of fire.

Edited September 1, 2021 by kerbiloid

[DDE]

Sorry to use you guys as suoer-Google, but some time ago someone like @nyrath covered an exotic form of particle that may lurk inside asteroids and be able to act as some form of fusion, or evwn antimatter generation enabler. No, it wasn't primordial black holes.

I need that McGuffinite for... reasons.