For Questions That Don't Merit Their Own Thread

[kerbiloid]

Just to be sure. Not a strangelet?

[DDE]

1 hour ago, kerbiloid said:

Just to be sure. Not a strangelet?

Nope. Turns out it's a quark nugget.

http://www.projectrho.com/public_html/rocket/slowerlight3.php#quarknuggets

Does the neighborhood McD serve these?

Wait, they are stranglets... does the whole thing make different assumptions about them, and that they're not the all-consuming monsters of CALYX HOLLOW fame?

[K^2]

That's basically the same thing. There are some models suggesting strange matter might be metastable, but we've never made nor observed any. If it exists, it can be used for many interesting things. That is, if you ever figure out how to contain it. Given that you'd need a considerable amount of it to be of any use, it would be exceptionally massive while still remaining exceptionally compact.

[JoeSchmuckatelli]

Wait... That site @DDElinked to might have some truth to it?

 

(I glanced at it, but then dismissed it as a kook site.)

 

[SOXBLOX]

4 hours ago, DDE said:

CALYX HOLLOW fame

"I understood that reference!"

[K^2]

19 hours ago, JoeSchmuckatelli said:

Wait... That site @DDElinked to might have some truth to it?

I don't know about the rest of the site, but the concept isn't entirely made up. Still, it's kind of in the vein of how scientist used to think that the metallic hydrogen might be a superfuel, but then we found that expectations of its metastability have been greatly inflated. We don't actually know if any of these exotic states of matter are metastable. We have no way to verify, and our ability to rely on theoretical results here is questionable at best. These kinds of densities push limits on how much we can decouple quantum mechanics from gravity, and that's on top of them being exceptionally hard problems in condensed matter physics in the first place.

The only thing that might lead to some better clues about feasibility of it all in our lifetime is the dark matter search. If we actually detect dark matter and it turns out to be strange, charmed, or some other form of exotic quark matter, we'll have our answer. If it turns out to be something else and our estimates for quantity of whatever it is match quantity of dark matter in the universe, then these metastable states are much less likely to be real.

One piece of evidence that makes me a bit skeptical of quark matter or any other compact object explanation for dark matter is the fact that we haven't found any evidence of primordial black holes. Same models that predict a lot of strange matter floating about predict a lot of primordial black holes floating about. Normally, sub-planetary mass black holes would be very hard to find, but there is a specific mass range that should be very obvious. Black holes that were created with just enough mass to evaporate over the age of the universe. We have looked for gamma ray bursts associated with the last moments of a black hole evaporation as it pops out of existence, and found absolutely nothing.

That leaves us with three possible explanations. 1) Black holes of sufficient mass to survive until now weren't produced - that seems unlikely based on amount of dark matter we're trying to explain here, and given how easy it would be for black holes to merge during early expansion. 2) Black holes don't evaporate or evaporate at a much different rate - plausible, but then we understand bleep-all about quantum gravity, and our predictions about stability of strange matter or conditions for its formations aren't worth the paper they're printed on. 3) Sufficient density fluctuations were nowhere near as common as some of these models suggest. In which case, these things might still be around, but nowhere near the quantity to explain dark matter.

I'm leaning towards that last option, which isn't definitive as far as stability of strange matter, but it takes away the biggest argument for its existence - that it explains dark matter. And without it, it's just a numerical curiosity of a particular model with no experimental evidence whatsoever. And either way, we can't make any, and if it's not common in the universe, we're not going to find some to use or experiment on.

[JoeSchmuckatelli]

Acknowledging the potential for this to be political... Hoping it won't be. 

I'd like to ask about the science of detection and avoidance of Havana Syndrome / directed energy weapons. 

https://en.m.wikipedia.org/wiki/Havana_syndrome

Current presumption is directed microwaves - is there a way to use a phone or something else cheap & ubiquitous to detect a directed energy attack if microwaves are the culprit? 

 

Early speculation resolved around sonic weapons as a possibility - given some of the symptoms. 

 

https://en.m.wikipedia.org/wiki/Sonic_weapon

Has this been discounted? 

Finally - does anyone know whether these need line of sight - or can they be used through walls, windows, etc.? 

[K^2]

21 minutes ago, JoeSchmuckatelli said:

Current presumption is directed microwaves - is there a way to use a phone or something else cheap & ubiquitous to detect a directed energy attack if microwaves are the culprit? 

Don't know about using cell phone hardware directly, but microwave detectors are really simple and cheap. Wouldn't be a trouble to create a dongle for it. That said, microwaves are usually pretty sell shielded by human skin. If the power is sufficient to start cooking your brain, your skin will be getting burns. This is why microwaves have been researched as means of safe-ish crowd dispersal. You start feeling like you're being burned long before there is actual damage. You'd have to drop down to very long wavelengths before you can start doing more damage to the brain, and by that point you're pumping so much EMF into the room you'll be tripping breakers from induced current.

25 minutes ago, JoeSchmuckatelli said:

Early speculation resolved around sonic weapons as a possibility - given some of the symptoms. 

That actually sounds way more plausible. Current theory on why head blows can cause unconsciousness is due to mechanoporation, and it's been long theorized that ultrasonic cavitation might lead to the same effect. The trouble is that with ultrasound, it's a very fine line between causing depolarization and doing tissue damage. No official medical research on something like this would ever be permitted. But off the books... The benefits are obvious. Any chemical agent causing unconsciousness will have a host of side-effects and is very easily detectable after the fact. If you could deliver equivalent of a blow to the head without any physical injury, well. Suppose, goal was to render diplomats unconscious for a brief period. The agency involved might have had success in the lab using ultrasound to induce unconsciousness on "volunteers". They try it in the field. Agents turn the system on, fumble with controls, get no results, increase power way beyond safe limits, and end up causing tissue damage. And the reason it failed could very well have been that real environment obstacles, like walls and windows, prevented delivering ultrasound the way it's meant to. If it was easy to apply in controlled manner, everyone would be doing it.

That's wild speculation, of course, and entirely ad-hoc. It fits MO of Russian intelligence, Soviet research, and what little is public knowledge about the symptoms. But that's a long throw away from anything conclusive. I just wouldn't be surprised, lets say. But if that's it, it's going to be relatively easy for other countries' intelligence to collect evidence on it and come up with countermeasures or at least means of detection. Again, this takes quite a bit of power, so the only subtlety here is that it's not audible without special equipment.

[kerbiloid]

Somebody bought on AliExpress the cheapest listening devices possible.

Whistling so loud, that whole embassy have their ears popped.

[DDE]

16 hours ago, K^2 said:

One piece of evidence that makes me a bit skeptical of quark matter or any other compact object explanation for dark matter is the fact that we haven't found any evidence of primordial black holes. Same models that predict a lot of strange matter floating about predict a lot of primordial black holes floating about. Normally, sub-planetary mass black holes would be very hard to find, but there is a specific mass range that should be very obvious. Black holes that were created with just enough mass to evaporate over the age of the universe. We have looked for gamma ray bursts associated with the last moments of a black hole evaporation as it pops out of existence, and found absolutely nothing.

That leaves us with three possible explanations. 1) Black holes of sufficient mass to survive until now weren't produced - that seems unlikely based on amount of dark matter we're trying to explain here, and given how easy it would be for black holes to merge during early expansion. 2) Black holes don't evaporate or evaporate at a much different rate - plausible, but then we understand bleep-all about quantum gravity, and our predictions about stability of strange matter or conditions for its formations aren't worth the paper they're printed on. 3) Sufficient density fluctuations were nowhere near as common as some of these models suggest. In which case, these things might still be around, but nowhere near the quantity to explain dark matter.

Going down the strangelet rabbit hole made me come across one guy who posits long-lived ball lightning are stragelets in the kiloton range.

[kerbiloid]

And now back to that strange ball above Tunguska...

[DDE]

15 hours ago, JoeSchmuckatelli said:

Current presumption is directed microwaves - is there a way to use a phone or something else cheap & ubiquitous to detect a directed energy attack if microwaves are the culprit? 

You aren't going to overbuild a commercial product. And if modern cell phones were packing this sort of power, well, the 5G loons would be very correct.

That's one angle of attack on the predominant hypothesis: alleged GRU wardrivers were caught in the Netherlands, meanwhile personnel with far more elaborate incriminating kit are ostensibly rowing across a multitude of non-Russian-friendly countries (up to and including downtown DC) where it wouldn't be a problem to capture them or even simply blow them away.

15 hours ago, JoeSchmuckatelli said:

Finally - does anyone know whether these need line of sight - or can they be used through walls, windows, etc.? 

Not sure about walls, but windows haven't been a problem for acoustic listening tech, therefore it should be possible to transmit a malicious sound inwards.

6 minutes ago, kerbiloid said:

And now back to that strange ball above Tunguska...

All the roads lead to Tunguska.

[kerbiloid]

50 minutes ago, DDE said:

Not sure about walls, but windows haven't been a problem for acoustic listening tech, therefore it should be possible to transmit a malicious sound inwards.

Afair, they (not those they, but just they) use(d) wi-fi router emission to 3d plot the human figures behind the wall.

[ARS]

On 9/1/2021 at 12:24 PM, SOXBLOX said:

However, I think it could still be detected, mostly because, to the receiver, it would be a notable blank spot in the sky.

Wait, so there's a difference on what appears on radar screen between 'looks like nothing there (because there really is nothing)' and 'looks like nothing there (because something is stealthing from radar detection)'?

[kerbiloid]

11 minutes ago, ARS said:

Wait, so there's a difference on what appears on radar screen between 'looks like nothing there (because there really is nothing)' and 'looks like nothing there (because something is stealthing from radar detection)'?

The white is brighter than the gray, but the black is where the gray is absent.

[magnemoe]

On 9/1/2021 at 7:24 AM, SOXBLOX said:

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. 

If it don't reflect radar signals it will show up as blank like the rest of the sky. 

In practice it reflect some and it depend on power level, distance and frequency.
Think you could easy get situations there the powerful search radar picks it up but not the missile with its smaller radar. 

Edited September 3, 2021 by magnemoe

[K^2]

7 hours ago, ARS said:

Wait, so there's a difference on what appears on radar screen between 'looks like nothing there (because there really is nothing)' and 'looks like nothing there (because something is stealthing from radar detection)'?

Modern radar is very heavily processed, so it's not like you're looking for a funny smudge on a screen indicating an anomaly. That went away with WWII radar tech. It's all about whether the system is designed to find such anomalies and present them to operator.

And as far as that goes, it depends very much on what you're looking for. Most ground-based radar stations aren't going to have a background to compare to, which is why stealth works. Unless you're running weather radar, the main reason to use radar at all is to not have to worry about clouds and such. So if you're just looking for an active radar return, you get the pitch black of open space as the backdrop. But you don't have to look for the return. There is plenty of static, and you can look for anomalies in that. That's what a passive radar does, and it can in theory pick out both types of anomalies. A plane will bounce off a lot of radio coming in from all sorts of sources, making it stand out, and you can look for that without attracting attention to your radar station. Likewise, a stealth plane will block out the background. But this is way, way harder to detect, primarily due to resolving power of your system.

If you want to pick up a plane with active radar, you don't need to worry about resolving power almost at all. If you pump enough power into the ping, you'll get a bounce and know its direction to within resolution. It's the same reason you can see stars even though they are point sources of light for all that it matters to our eye. If you are looking for a bounce with passive radar, you need a larger dish or array, because the power you get back is inherently limited and now you actually need to resolve the return better. But it's still a bright "dot" over a darker background. That's not so bad. If you are looking for a dark spot, now you have to actually resolve it to at least a single "pixel" to be detectable. And unlike active radar, where you get to pick the frequency to work with, for passive radar, you get to use what's there. If we are relying on ground signals bouncing from ionosphere, you won't get a lot past 1GHz or so. That's 30cm. If you are trying to spot a plane 10km away that has a 50m wing span by the fact that it's blocking a 30cm background, you're going to need a radar array 60m across. You could look for anomalies in microwave background, which has much higher frequency, but then the intensity isn't there, and you're basically going to need a radio telescope anyways.

If your radar is flying, there is more you can do. An active radar sweeping down, using ground as backdrop, can actually be very powerful. You get to pick the frequency range, pump a lot more power into the ping, and you can use time-of-flight to resolve the return instead of just angular resolution. If the stealth planes are trying to sneak by at low altitude, a high flying AWAC should be able to find them by the "hole" they're leaving in the ground return. Is that actually used? I have no idea, but I'd be surprised if nobody at least tried.

[SOXBLOX]

3 hours ago, K^2 said:

If your radar is flying, there is more you can do. An active radar sweeping down, using ground as backdrop, can actually be very powerful. You get to pick the frequency range, pump a lot more power into the ping, and you can use time-of-flight to resolve the return instead of just angular resolution. If the stealth planes are trying to sneak by at low altitude, a high flying AWAC should be able to find them by the "hole" they're leaving in the ground return. Is that actually used? I have no idea, but I'd be surprised if nobody at least tried.

The team that designed the F-117 also designed a small-scale stealth demonstrator ship. During the Navy's trials, they found that, for overhead radar emitters, it actually stood out against the ocean background more than it would have if it were non-stealth. That, plus the fact that the shape was secret, made them toss out the project.

IDK, I guess that's relevant...

[kerbiloid]

4 hours ago, SOXBLOX said:

The team that designed the F-117

MicroProse?

Spoiler

 

4 hours ago, SOXBLOX said:

also designed a small-scale stealth demonstrator ship.

Spoiler

 

[JoeSchmuckatelli]

Fascinating image:

This is the Centaurus A galaxy.

While the dust clouds are beautiful... the thing that strikes me is the glow.

For the telescope to pick up this glow - doesn't that imply a significant amount of dust beyond those dark clouds we see?  (To glow - does not the light from the galaxy have to reflect off of and scatter from... something?  i.e. dust and gas beyond those beautiful dark and illuminated tendrils?)

 

[kerbiloid]

1 hour ago, JoeSchmuckatelli said:

doesn't that imply a significant amount of dust beyond those dark clouds we see?

Spoiler

 

***

The thing on photo is in Cen(taurus).
The Great Attractor, to which we move, is in Norma.

Spoiler

Still any doubts?

Edited September 6, 2021 by kerbiloid

[SOXBLOX]

2 hours ago, JoeSchmuckatelli said:

For the telescope to pick up this glow - doesn't that imply a significant amount of dust beyond those dark clouds we see?  (To glow - does not the light from the galaxy have to reflect off of and scatter from... something?  i.e. dust and gas beyond those beautiful dark and illuminated tendrils?)

At any scale smaller than the galactic, your assumption would be correct. But that's not dust you're seeing. That glow is a giant cloud of stars. The brown dustlane running through the center is dust, though.

[JoeSchmuckatelli]

10 hours ago, SOXBLOX said:

That glow is a giant cloud of stars. The brown dustlane

I know that the dust lane is illuminated by stars behind it - I'm talking about the halo glow above and below.  It's bright enough to dim the light from the stars behind.  The translucent spherical glow that the band crosses - the stars behind the band not only backlight the band, but also light up the surrounding area like a streetlight in fog. 

It's that part of the photo that has caught my attention. 

 

 

[JoeSchmuckatelli]

It got me thinking about this post (and related discussions with @K^2... 

"It might be that the ratio in spacings is preserved in red shift, not the absolute spacing, but same principle.
 

    In scattering, you lose some of the intensity of light, and you might lose more at some wavelengths than others. So the overall shape of the spectrum, the envelope if you will, can actually end up similarly distorted, but the gaps will stay exactly where they were.
 

    Edit: This is a very artificial example. I made up all of the parameters, but it's good as an illustration.
 

     

    You have intensity on the Y axis and frequency on the X axis. So redder light to the left, bluer to the right, but you can pretty much ignore the actual numbers. The dashed curve is the original spectrum. It's the black body radiation with three gaps.
 

    Red curve simulates red shift. Everything is proportionally shifted to the left, which includes both the overall shape of the curve and all the gaps.
 

    Blue curve simulates scattering. I did compensate for the intensity loss, because you can't be certain about how bright the source is, so it's valuable to compare the light at the same relative intensity, but other than that, this is pretty realistic to what you might get. You can see that  the overall shape is not that different from red shift, and to the eye, if this is in visible range, they'd look close to identical. Even if you were measuring, given various sources of noise, you might not be able to distinguish between the two all that well. But the gaps in spectrum stay exactly where they were with the original. There is almost no light coming in at these frequencies, so scattering doesn't affect it at all."
 

... 

 

The question then is - if this galaxy is unique in having enough dust around it to have a halo like this or if it's just uniquely illuminating its cloud and most galaxies are like this? 

 

Weird quote due to the mobile version of the website (I think) 

 

Edited September 6, 2021 by JoeSchmuckatelli

[SOXBLOX]

4 hours ago, JoeSchmuckatelli said:

I'm talking about the halo glow above and below. 

I was, too. The halo-y glow that covers most of the image is stars. They're just not resolved in this image, the same way as how the Milky Way, to our eyes, on a clear night looks like a glowing cloud.

All the stars which you can see distinctly are foreground stars; they're part of the Milky Way.