5 ms·

Plasma, the Mysterious and Powerful Fourth Phase of Matter

86 points by nmat 8y ago

dang 8y ago
Url changed from https://singularityhub.com/2018/06/30/plasma-the-mysterious-and-powerful-fourth-phase-of-matter/ https://singularityhub.com/2018/06/30/plasma-the-mysterious-..., which points to this.
flatfilefan 8y ago
So what about the Russian Avantgarde hypersonic warhead that should fly covered in a plasma fireball? Do you guys care about this stuff? Is it even feasible?
- gpm 8y ago
  > hypersonic warhead that should fly covered in a plasma fireball s/warhead/capsule/ and you've just described "normal" for returning from space. I imagine that a warhead is designed to slow down slower, and thus to remain hypersonic farther into the atmosphere, but of course it's possible, it's just a question of how good you can make it.
  - flatfilefan 8y ago
    It should be able to get to 40km altitude and maneuver at 6 mach while sustaining a horizontal flight making it impossible to intercept by a missile defense. So I wonder whether plasma research is suddenly again in vogue because of it?
    - jjoonathan 8y ago
      Here is a US missile maneuvering at mach 10 to intercept a RV going at mach 30. In 1972. https://youtu.be/msXtgTVMcuA?t=60 https://youtu.be/msXtgTVMcuA?t=60 Russia loves to brag about weapons that can overcome US defenses because people for some reason have forgotten that the top-level strategic "defense" is not an impenetrable wall of interception systems -- which literally no nation on earth has the budget to effectively maintain, even the US, because the economics of intercept are terrible -- but rather the policy of mutually assured destruction. This has been the case throughout the entire planning cycle of nearly every piece of hardware in use by the US armed forces and it will continue to be the case for the foreseeable future.
      - dragonwriter 8y ago
        > Russia loves to brag about weapons that can overcome US defenses because people for some reason have forgotten that the top-level strategic "defense" is not an impenetrable wall of interception systems -- which literally no nation on earth has the budget to effectively maintain, even the US, because the economics of intercept are terrible -- but rather the policy of mutually assured destruction. No, Russia likes to heavily advertise weapons that can penetrate US missile defenses as a means of reinforcing MAD; any power’s decision-makers gaining (justified or not) confidence in even limited survivability due to workable defenses undermines MAD. This is also the same reason all parties want to project an air of confidence in their defenses; they want to appear unconstrained by MAD (so that they can use nuclear threat, implicit or explicit, to influence rival powers non-nuclear-attack actions) while the other side remains constrained (so that the assured destruction, at least in political effect, is not mutual.)
        jjoonathan 8y ago
        > No, Russia likes to heavily advertise weapons that can penetrate US missile defenses as a means of reinforcing MAD We agree. I'm not sure why you opened with "no." I'd add that I suspect the primary motivation is arms salesmanship, but that hardly excludes reinforcing MAD. > all parties ... want to appear unconstrained by MAD I haven't seen any such (ridiculous) claims, but I don't have trouble imagining that they exist.
        dragonwriter 8y ago
        > I haven't seen any such (ridiculous) claims It's pretty nuclear deterrence theory; the major powers both want (1) to actually be survivable and thus free to use any means at their disposal knowing that the other side cannot impose unacceptable costs in return, (2) failing that, appear to the opponent to believe that they are in such a condition, so that the opponent must act as if they will feel free to escalate unbound by fear of retribution even if they rationally should not, and, in any case, (3) prevent the opponent from perceiving (whether or not it is correct) themselves safe from retribution, so the opponent cannot escalate unchecked. MAD is just the state where both powers acheive #3; it is consistent with either or both powers also acheiving limited success at #2 (which means that policy which doesn't involve nuclear provocation or similar existential threat must be constrained by the risk of nuclear escalation by the other side—if neither side has any success at #2, that concern does not exist.)
    - gpm 8y ago
      To the extent that plasma research is in fashion I think it's because fusion energy is looking somewhat plausible again. Advances in super conductors, computer modeling, etc make is seem like fusion power might actually be 15 years away this time.
      - flatfilefan 8y ago
        A running gag has it as “It was 20 years away in the 60ies and only 15 years away as of today”. This evasive nature of the fusion makes me think it’s something else.
zyxzevn 8y ago
What is the difference between the Zeeman effect and the Stark effect?
- ridgeguy 8y ago
  Zeeman effect - spectrum line splitting by a magnetic field Stark effect - spectrum line splitting by an electric field
  - deleted 8y ago
    [deleted]
georgecmu 8y ago
We rarely encounter natural plasma, unless we’re lucky enough to see the Northern lights, or if we look at the Sun through a special filter, or if we poke our head out the window during a lightning storm, as I liked to do when I was a kid. Right. Anyone who ever struck a match has produced a natural plasma right then and there. Neon lights and plasma [!] TVs are pretty common this side of the Atlantic. A fun way to create a microwave plasma is to microwave half a grape [1]. An even more fun way is to leave a fork in the microwave oven. [1] https://physics.stackexchange.com/questions/37836/why-do-grapes-in-a-microwave-oven-produce-plasma https://physics.stackexchange.com/questions/37836/why-do-gra...
- dnautics 8y ago
  We really optimized this and it's better to cut your grape into quarters (sixths seem to perform as well as quarters, so there's diminishing returns):
- Areading314 8y ago
  I think the operative word here is "natural", which does not include matches, microwaves, or TVs
- mockingbirdy 8y ago
  In the comments of the Q&A you've linked they say it's not plasma, it's just normal flames with ions.
  - ta78885578 8y ago
    Yeah it seems plasma gets used a bit lightly. I was under the impression you need stonking amounts of pressure or heat.

86 points by nmat 8y ago

dang 8y ago

Url changed from https://singularityhub.com/2018/06/30/plasma-the-mysterious-and-powerful-fourth-phase-of-matter/ https://singularityhub.com/2018/06/30/plasma-the-mysterious-..., which points to this.

flatfilefan 8y ago

So what about the Russian Avantgarde hypersonic warhead that should fly covered in a plasma fireball? Do you guys care about this stuff? Is it even feasible?

gpm 8y ago
> hypersonic warhead that should fly covered in a plasma fireball s/warhead/capsule/ and you've just described "normal" for returning from space. I imagine that a warhead is designed to slow down slower, and thus to remain hypersonic farther into the atmosphere, but of course it's possible, it's just a question of how good you can make it.
- flatfilefan 8y ago
  It should be able to get to 40km altitude and maneuver at 6 mach while sustaining a horizontal flight making it impossible to intercept by a missile defense. So I wonder whether plasma research is suddenly again in vogue because of it?
  - jjoonathan 8y ago
    Here is a US missile maneuvering at mach 10 to intercept a RV going at mach 30. In 1972. https://youtu.be/msXtgTVMcuA?t=60 https://youtu.be/msXtgTVMcuA?t=60 Russia loves to brag about weapons that can overcome US defenses because people for some reason have forgotten that the top-level strategic "defense" is not an impenetrable wall of interception systems -- which literally no nation on earth has the budget to effectively maintain, even the US, because the economics of intercept are terrible -- but rather the policy of mutually assured destruction. This has been the case throughout the entire planning cycle of nearly every piece of hardware in use by the US armed forces and it will continue to be the case for the foreseeable future.
    - dragonwriter 8y ago
      > Russia loves to brag about weapons that can overcome US defenses because people for some reason have forgotten that the top-level strategic "defense" is not an impenetrable wall of interception systems -- which literally no nation on earth has the budget to effectively maintain, even the US, because the economics of intercept are terrible -- but rather the policy of mutually assured destruction. No, Russia likes to heavily advertise weapons that can penetrate US missile defenses as a means of reinforcing MAD; any power’s decision-makers gaining (justified or not) confidence in even limited survivability due to workable defenses undermines MAD. This is also the same reason all parties want to project an air of confidence in their defenses; they want to appear unconstrained by MAD (so that they can use nuclear threat, implicit or explicit, to influence rival powers non-nuclear-attack actions) while the other side remains constrained (so that the assured destruction, at least in political effect, is not mutual.)
      - jjoonathan 8y ago
        > No, Russia likes to heavily advertise weapons that can penetrate US missile defenses as a means of reinforcing MAD We agree. I'm not sure why you opened with "no." I'd add that I suspect the primary motivation is arms salesmanship, but that hardly excludes reinforcing MAD. > all parties ... want to appear unconstrained by MAD I haven't seen any such (ridiculous) claims, but I don't have trouble imagining that they exist.
        dragonwriter 8y ago
        > I haven't seen any such (ridiculous) claims It's pretty nuclear deterrence theory; the major powers both want (1) to actually be survivable and thus free to use any means at their disposal knowing that the other side cannot impose unacceptable costs in return, (2) failing that, appear to the opponent to believe that they are in such a condition, so that the opponent must act as if they will feel free to escalate unbound by fear of retribution even if they rationally should not, and, in any case, (3) prevent the opponent from perceiving (whether or not it is correct) themselves safe from retribution, so the opponent cannot escalate unchecked. MAD is just the state where both powers acheive #3; it is consistent with either or both powers also acheiving limited success at #2 (which means that policy which doesn't involve nuclear provocation or similar existential threat must be constrained by the risk of nuclear escalation by the other side—if neither side has any success at #2, that concern does not exist.)
  - gpm 8y ago
    To the extent that plasma research is in fashion I think it's because fusion energy is looking somewhat plausible again. Advances in super conductors, computer modeling, etc make is seem like fusion power might actually be 15 years away this time.
    - flatfilefan 8y ago
      A running gag has it as “It was 20 years away in the 60ies and only 15 years away as of today”. This evasive nature of the fusion makes me think it’s something else.

zyxzevn 8y ago

What is the difference between the Zeeman effect and the Stark effect?

ridgeguy 8y ago
Zeeman effect - spectrum line splitting by a magnetic field Stark effect - spectrum line splitting by an electric field
- deleted 8y ago
  [deleted]

georgecmu 8y ago

We rarely encounter natural plasma, unless we’re lucky enough to see the Northern lights, or if we look at the Sun through a special filter, or if we poke our head out the window during a lightning storm, as I liked to do when I was a kid. Right. Anyone who ever struck a match has produced a natural plasma right then and there. Neon lights and plasma [!] TVs are pretty common this side of the Atlantic. A fun way to create a microwave plasma is to microwave half a grape [1]. An even more fun way is to leave a fork in the microwave oven. [1] https://physics.stackexchange.com/questions/37836/why-do-grapes-in-a-microwave-oven-produce-plasma https://physics.stackexchange.com/questions/37836/why-do-gra...

dnautics 8y ago
We really optimized this and it's better to cut your grape into quarters (sixths seem to perform as well as quarters, so there's diminishing returns):
Areading314 8y ago
I think the operative word here is "natural", which does not include matches, microwaves, or TVs
mockingbirdy 8y ago
In the comments of the Q&A you've linked they say it's not plasma, it's just normal flames with ions.
- ta78885578 8y ago
  Yeah it seems plasma gets used a bit lightly. I was under the impression you need stonking amounts of pressure or heat.