Science stories of the week

Discussion in 'General Science & Technology' started by wegs, Jan 31, 2021.

  1. wegs Matter and Pixie Dust Valued Senior Member

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    Last edited: Aug 12, 2021
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  3. exchemist Valued Senior Member

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    Destroy it , obviously.

    This situation is no different and no more sad than that of any farmer who is found to have a cow with TB. It's a notifiable disease of livestock and the animal must be destroyed. That's the law. The fact that a Silly Season campaign has been whipped up about this alpaca is neither here nor there.

    It would be irrational to leave this animal alive and would immediately set a precedent that would completely undermine the regulations.
     
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  5. wegs Matter and Pixie Dust Valued Senior Member

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    Agree. Geronimo’s owner is a vet as well, you’d think she’d know better. As sad as it is, it’s the right thing to do for other animals and public health safety. Not sure why she doesn’t believe the “positive” tests, unless that’s just for show.
     
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  7. wegs Matter and Pixie Dust Valued Senior Member

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    But, just to be on the safe side, don't walk under any ladders today, and avoid black cats.

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    https://www.livescience.com/63032-friday...tions.html

    The science is clear: Friday the 13th is a normal day. Yet, people continue to think this is destined to be a bad day. "It helps people to reduce anxiety," said Neil Dagnall, a parapsychologist at Manchester Metropolitan University. "Superstition generally serves as a mechanism to provide reassurance," he said.
     
  8. sculptor Valued Senior Member

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    triskaidekaphobia
    works for tall buildings too
     
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  9. sideshowbob Sorry, wrong number. Valued Senior Member

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    My building has 24 apartments - numbered 1-25.

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  10. wegs Matter and Pixie Dust Valued Senior Member

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    https://www.upi.com/Science_News/20...51628874418/?utm_source=spigot&utm_medium=sci

    Aug. 13 (UPI) -- Small particulate matter pollution in wildfire smoke in the western United States increases the risk for COVID-19 infection and death from the disease in people living in affected regions, a study published Friday by Science Advances found.

    Nearly 20,000 COVID-19 cases and 750 deaths in California, Oregon and Washington between March and December of last year may be linked with a rise in fine particulate air pollution, or PM2.5, generated by the wildfires plaguing the region, the researchers said.


    I wonder if this study will change any minds when it comes to climate change, as far as it not being considered (by many) to be an imminent threat.
     
    Last edited: Aug 14, 2021
  11. sculptor Valued Senior Member

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    Apollo 13
    just a coincidence?
    maybe
    Nasa could have used a dose of triskaidekaphobia?
     
  12. geordief Valued Senior Member

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    Is this a good story or just another update in the seemingly never ending saga of the hope of getting energy from nuclear fusion?

    "
    US lab stands on threshold of key nuclear fusion goal"

    "An experiment suggests the goal of "ignition", where the energy released by fusion exceeds that delivered by the laser, is now within touching distance"

    https://www.bbc.com/news/science-environment-58252784?piano-footer
     
  13. Q-reeus Valued Senior Member

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    From the BBC article linked to:
    "An experiment carried out on 8 August yielded 1.35 megajoules (MJ) of energy - around 70% of the laser energy delivered to the fuel capsule. Reaching ignition means getting a fusion yield that's greater than the 1.9 MJ put in by the laser.

    "This is a huge advance for fusion and for the entire fusion community," Debbie Callahan, a physicist at the Lawrence Livermore National Laboratory, which hosts NIF, told BBC News."

    Oh really? Let's see if anyone apart from myself can spot what should be obvious deceptive hype. Anyone?
     
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  14. sculptor Valued Senior Member

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    pipe dream ?
     
  15. Q-reeus Valued Senior Member

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    Very likely the case, but I had something considerably more specific in mind than that.
     
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  16. sculptor Valued Senior Member

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    %
    ?
     
  17. Q-reeus Valued Senior Member

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    Note carefully the wording in the passage I cited:
    "...yielded 1.35 megajoules (MJ) of energy - around 70% of the laser energy delivered to the fuel capsule. Reaching ignition means getting a fusion yield that's greater than the 1.9 MJ put in by the laser."
    How meaningful is that benchmark labeled 'reaching ignition'? One or more relevant factors missing perhaps?
     
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  18. sculptor Valued Senior Member

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    only losing 30%(or more or less) of the applied power seems to be part of the expected pattern when bragging about fusion progress
     
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  19. exchemist Valued Senior Member

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    There seem to be a number of things. They say they need to do this with larger amounts of fuel and acknowledge the difficulty of keeping it together long enough for fusion. Considering this technique relies on inertial confinement, i.e. zapping it with enough energy to make it fuse before it can expand, that won't be easy. And then there is the issue of how you get the released energy out in a form that you can convert to electricity.

    I remain a fusion sceptic, I'm afraid.
     
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  20. Q-reeus Valued Senior Member

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    Well it's actually a lot worse than that suggests. The key deceptive bit was '...of the laser energy delivered to the fuel capsule.' Let's make the unrealistic assumption an impossible 100% of laser energy was delivered. What's missing? For starters, net laser efficiency itself. The actual conversion efficiency of original input energy to output UV laser energy is less than 1%.
    Just that factor alone means the rosy sounding '70% of 'ignition' level is really less than 0.7% of nominal input energy. See last para here:
    https://en.wikipedia.org/wiki/National_Ignition_Facility#NIF_and_ICF

    "These output energies are still less than the 422 MJ of input energy required to charge the system's capacitors that power the laser amplifiers. The net wall-plug efficiency of NIF (UV laser energy out divided by the energy required to pump the lasers from an external source) would be less than one percent, and the total wall-to-fusion efficiency is under 10% at its maximum performance. An economical fusion reactor would require that the fusion output be at least an order of magnitude more than this input. Commercial laser fusion systems would use the much more efficient diode-pumped solid state lasers, where wall-plug efficiencies of 10 percent have been demonstrated, and efficiencies 16-18 percent are expected with advanced concepts under development.[28]"
    And why have these far more efficient lasers not been long substituted? Perhaps because they are plagued with stability issues etc? Even with such an improvement, the odds still look very long overall.

    What else? How about the thorny issue of how to capture and efficiently convert the 'over in a nanosecond' mini-nuke explosion? Collection by whatever physical means has to not obstruct the very evenly spaced spherical array of 192 input laser beams. Nor foul the delicate laser optics system. I would be surprised if the already less than 0.7% net burn efficiency of current 'breakthrough' result could be converted to useful electricity at more than around 10% or so efficiency. There is then further significant losses incurred in needing to recycle sufficient of that useful electrical collected energy back into the lasers driving ignition. Themselves a very complex and multi-staged system.

    Is this all looking good so far? Don't think so!

    What else? Well it turns out the extraordinarily complex and delicate massive NIF facility has a certain 'throughput problem' to put it mildly. Last para here:
    https://en.wikipedia.org/wiki/National_Ignition_Facility#Driver_laser

    "One important aspect of any ICF research project is ensuring that experiments can actually be carried out on a timely basis. Previous devices generally had to cool down for many hours to allow the flashlamps and laser glass to regain their shapes after firing (due to thermal expansion), limiting use to one or fewer firings a day. One of the goals for NIF is to reduce this time to less than four hours, in order to allow 700 firings a year.[22]"
    Ha ha ha ha. Saying no more there.

    Misleading hype is nothing new when it comes to the NIF saga. Check out the following:
    https://en.wikipedia.org/wiki/National_Ignition_Facility#Breakeven_claims

    Perhaps most significant is the final para of introductory section:

    "Bringing the system to its full potential was a lengthy process that was carried out from 2009 to 2012. During this period a number of experiments were worked into the process under the National Ignition Campaign, with the goal of reaching ignition just after the laser reached full power, some time in the second half of 2012. The Campaign officially ended in September 2012, at about 1⁄10 the conditions needed for ignition.[7] Experiments since then have pushed this closer to 1⁄3, but considerable theoretical and practical work is required if the system is ever to reach ignition.[8] Since 2012, NIF has been used primarily for materials science and weapons research."

    I recall coming across the latter aspect quite some years back. The whisper then being the true goal all along was using NIF as a test-bed for developing 'pure fusion nukes' i.e eliminating fission triggering. That in turn would mean 'clean nukes' which in turn would basically erode the barrier to their use as tactical weapons since fallout would ostensibly no longer be a political issue. And notionally they could be made to operate over a much larger yield size range.

    Thankfully maybe, that is also looking like remaining a pipe dream given the poor results from humongous efforts so far expended.
     
    Last edited: Aug 18, 2021
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  21. Q-reeus Valued Senior Member

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    I had prepared above reply before seeing your post, but I think it more or less covers your own criticisms.
     
  22. exchemist Valued Senior Member

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    I had missed your point about the low efficiency of lasers, though.

    Looking at this:

    Laser systems operating in the megajoule range are predicted to undergo ignition with a gain of at least 10, and the NIF is expected to generate 20 MJ of fusion energy per pulse, although yields of up to 46 MJ are theoretically possible, [1,6,7]. Although ignition would be a milestone in its own right, the energy released at NIF would still be an order of magnitude less than the energy pumped into the capacitors to drive the laser, so the device does not even come close to breaking even from an engineering standpoint. In addition, NIF is only able to fire one shot every few hours, while a realistic reactor would need to fire around 10 times a second. However, by adapting technology from Livermore's Mercury laser, it appears very likely that these obstacles can be overcome. [8,9]

    From: http://large.stanford.edu/courses/2010/ph240/hamerly2/

    it seems efficiency of the laser may be closer to 10% than 1%, but even so it would mean that, once they get to the elusive ignition point, they are still at least one order of magnitude from anything self-sustaining.

    And then there's the issue of repeat firing speed........and the issue of energy collection and conversion..........etc etc.

    I still don't see commercial fusion in the next 30 years, frankly, if ever. I suspect we will go the conventional renewables route and won't need it. But I won't be around to find out in any case.
     
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  23. Q-reeus Valued Senior Member

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    That passage from Stanford site sounded quite optimistic. Adopting technology from the fabulous Mercury laser would create orders of magnitude improvement across the board.
    Alas, the Hg seems to have run through their collective fingers. Why would I say that? The date of the article shown at top - 2010. Hyped hope bites the dust again.
    Certainly tend to agree with your final assessment there.

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    Various players like Lockheed Martin, General Atomics, NRL, are working on 'game changing' 'Compact Fusion' reactors. Just do a search using 'compact fusion power'. How much is hype vs reality only time will tell.
     
    Last edited: Aug 19, 2021

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