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  1. .Scott

    B Sabine Hossenfelder on the search for new particles

    Physicists are looking for their diamonds and she seems to want to fence off large plots of investigative territory that she rates as far too unpromising. If she was looking to improve the situation, she should have made more specific criteria for how she would rate "promising" vs...
  2. .Scott

    Artemis 1 going to the Moon (mid November)

    From inverse.com.
  3. .Scott

    Space Stuff and Launch Info

    Here is what I see from the Atlas telescope shot: 1) The collision occurs and a relatively small amount (compared to the full asteroid) of material is ejected. 2) The ejected material spreads out and quickly become too dispersed to track. 3) On the Atlas video, it appears the collision occurred...
  4. .Scott

    Artemis 1 going to the Moon (mid November)

    Somewhere in the NASA coverage I read that if it gets into December, they run into a long list of booster devices expiring - and thus more time in the VAB. Perhaps the "planning" they are doing now will take greater advantage of the VAB visit than just the FTS.
  5. .Scott

    Artemis 1 going to the Moon (mid November)

    The SLS just arrived at the VAB - so it is now safe from the weather. With SLS at the VAB, NASA should be able to get caught up on all the scheduled servicing - including the FTS. So I do not expect that they will need an FTS extension. Edit: NASA just posted another SLS update...
  6. .Scott

    B Is there another workable interpretation of the Bell Inequality?

    In the article's attempt to reconcile gravity and particle physics, they describe a way to view adding information to the universe. And they highlight the distinctiveness of such new information. It builds on their argument that there is a way out of the paradox - though I do not fully follow...
  7. .Scott

    B Is there another workable interpretation of the Bell Inequality?

    I just read an article in Quantum Magazine about "unitary" results and how this is tied to looking at the reversibility of quantum events. It provided an easy-to-understand mechanism for tracking the effects of adding information to a fictional universe. The example they gave for detecting a...
  8. .Scott

    Artemis 1 going to the Moon (mid November)

    It is possible that Starship will launch first. If that happens, it would mean that the SLS would never launch as the most powerful rocket. Both Starship and SLS are parts of the Artemis program and, per current plans, both will be used in the first return of astronauts to the moon in 2025.
  9. .Scott

    Artemis 1 going to the Moon (mid November)

    As @mfb noted, the Tuesday launch is unscrubbed - but still far from a certainty. Hurricane Ian has not moved that much and tropical force winds are not expected at the cape until early Wed. morning - perhaps time to move SLS to the VAB after the launch window has expired. NASA has postponed a...
  10. .Scott

    Artemis 1 going to the Moon (mid November)

    Apparently, that would be too much drama for NASA. The Tuesday, September 27 launch is scrubbed. https://blogs.nasa.gov/artemis/2022/09/24/artemis-i-managers-wave-off-sept-27-launch-preparing-for-rollback/ They will decide on whether to return SLS to the VAB tomorrow.
  11. .Scott

    Artemis 1 going to the Moon (mid November)

    Just to keep in suspense, Tropical Storm Ian has now slowed. Per todays 11am forecast chart below, tropical force winds will arrive at the launch site after 8pm Tuesday. Will Ian allow the launch or won't it? Stay tuned... Actually, it could become even more suspenseful than that. On...
  12. .Scott

    Artemis 1 going to the Moon (mid November)

    Ars Technica has an interesting article about NASA's plans . But one caution: The article talks about FTS "battery life" but during the Wednesday live feed it was explained that the FTS waiver issue was not really a "battery life" issue. What is interesting in the article is that NASA is...
  13. .Scott

    I How can gravitons have anti particles?

    No one is laughing at you. Your curiosity is at the heart of Physics.
  14. .Scott

    I How can gravitons have anti particles?

    As I understand it, that would be essential in recognizing a particle as a graviton - so lots of people wonder how to detect that spin.
  15. .Scott

    Artemis 1 going to the Moon (mid November)

    From Fox Weather: They have the Space Force waiver. So if they return to the VAB, it'll for the tropical storm, not the FTS.
  16. .Scott

    I How can gravitons have anti particles?

    I don't believe that the spin in intrinsically positive or negative. It's relative to the measuring device - or to the particles it interacts with.
  17. .Scott

    Artemis 1 going to the Moon (mid November)

    Regarding the Tuesday, Sept 27th: https://www.nhc.noaa.gov/refresh/graphics_at4+shtml/145524.shtml?mltoa34#contents
  18. .Scott

    Artemis 1 going to the Moon (mid November)

    NASA announced that this test went well enough to go for a 9/27 launch. This topic will be discussed on NASA Live in 2 hours (12:30pm ET 9/23/2022). The press release is at: https://www.nasa.gov/press-release/nasa-to-provide-media-update-on-demonstration-test-artemis-i-mission "Based on data...
  19. .Scott

    I How can gravitons have anti particles?

    So I am thinking about particle annihilation - and I am probably not going to get this right - but here's my naïve whack at it: As I understand it, both Photons and Gravitons are massless - so they travel at light speed and can carry a range of energy. We can have relatively low-energy...
  20. .Scott

    Combinational Coding

    Let's see, sounds recursive to me. With no attempts at optimization:
  21. .Scott

    Artemis 1 going to the Moon (mid November)

    There was actually more information about how the testing was progressing than you commonly get with a SpaceX test. There was more information about that FTS battery issue. It's sounding to me like the 25-day limit is tied a lot more to guaranteeing regular FTS equipment access to the Range...
  22. .Scott

    Artemis 1 going to the Moon (mid November)

    2:07pm: Upper stage QD Boot Containment was lost. Has happened before. Doesn't sound very important. 2:11pm: Fast fill for both LOX and LH in upper stage. (meanwhile - Elon says Starship flight very likely in November) 3:15pm NASA Announcement: Upper stage LH in the "Topping" stage. The...
  23. .Scott

    Artemis 1 going to the Moon (mid November)

    1:11pm NASA Announcement: They just reached "replenish" on the LH tank - so "Fast Fill" has completed successfully. 1:19pm: NASA decided earlier not to start the upper stage fueling on schedule. They are now deciding whether to go for that part of the test or not. 1:35pm: No news on the...
  24. .Scott

    Artemis 1 going to the Moon (mid November)

    12:43am NASA Announcement: LH 67% tank. NASA has decided to increase the storage tank pressure to nominal. With the process based on the procedure up to this point, it would take about 2 hours to fill the LH tank. The 10%, 5 minute limit would stop the fill at either 10% H2 concentration or 5...
  25. .Scott

    Artemis 1 going to the Moon (mid November)

    It's the H2 concentration in the LH QD Cavity. There are two mitigating issues regarding an explosion: 1) That cavity has no ignition sources. 2) The equipment in that region is pretty rugged - a moderate H2 "explosion" could be taken in stride. But clearly, they are not being overly...
  26. .Scott

    Artemis 1 going to the Moon (mid November)

    The new concentration limit is actually "10% for 5 minutes" - with no further explanation. Not clear to me whether the 5 minutes starts at 4% or 10%. 12:07: 35% LH full, leak concentration is "under 1%" (no longer "about 0.5%"). 12:12: Engine kick start bleed has started and is nominal. Leak...
  27. .Scott

    Artemis 1 going to the Moon (mid November)

    11:35am NASA Announcement: They are in LH Fast Fill - and apparently no important leak yet. 11:45am NASA Announcement: As the pressure increased, an 0.5% leak has developed. The % measurement is the concentration of hydrogen in a cavity near the Quick Disconnect. They are going to continue to...
  28. .Scott

    Artemis 1 going to the Moon (mid November)

    11:08am: Temperature cycling complete. New plan: when refueling (LH) this time with a pressure reduction in the storage tank to only 5psi and then a very slow LH pressure build-up. They have also repeated that the leak stopped immediately after the flow stopped.
  29. .Scott

    Artemis 1 going to the Moon (mid November)

    It doesn't sound "too restrictive" to me. The LH leak limit is 4%, they are seeing "7% concentration". I have not been able to find an exact and explicit description of what the numerator and denominator are in that 4% limit. However, this LH leak is into an environment rich in O2 - because...
  30. .Scott

    Artemis 1 going to the Moon (mid November)

    NASA has never "mastered" LH fueling - in the sense that they can created results that matched the design intent on the first try. In this case, the NASA live coverage is reporting that today's fault is identical to the Quick Disconnect fault that happened on Sept 3rd.
  31. .Scott

    Artemis 1 going to the Moon (mid November)

    At 10:13: The "leak team" has just reported to the launch director that the leak profile is identical to the leaks during those previous attempts. They will attempt to cycle temperatures in an attempt to better seat the connection. Next attempt around 10:45am.
  32. .Scott

    Artemis 1 going to the Moon (mid November)

    Tanking began at 9:09am ET. Hydrogen "Fast fill" is expected at about 10:30am. Completion at about 3:30pm. So far, so good. Hydrogen "Fast Fill" will start sooner. NASA reports that the Hydrogen temperature inlet sensor was not working - and that has affected the Liquid Hydrogen (LH) "Fast...
  33. .Scott

    Artemis 1 going to the Moon (mid November)

    The fueling test is tomorrow: space.com According to another website, work starts at 7:15am tomorrow.
  34. .Scott

    Artemis 1 going to the Moon (mid November)

    Perhaps NASA's history with LH2 might steer you toward a more pessimistic launch date.
  35. .Scott

    Getting a Crying Baby to Sleep

    A study published in "Current Biology" describes a method for getting crying infant to sleep. That method: -- 1) Carry infant while walking for 5 minutes. -- 2) Continue to hold infant for another 5 to 8 minutes. In my household, this is very similar to "Daddy's method for getting the baby to...
  36. .Scott

    Artemis 1 going to the Moon (mid November)

    I don't either. And I'm wondering whether the reason that Space Force hasn't put a quick kibosh to a 45-day extension is that after the next cryo test it could become a 65-day extension. NASA's been struggling with LH2 leaks for decades.
  37. .Scott

    Artemis 1 going to the Moon (mid November)

    According to "Florida Today", the cryo test will be No Earlier Than (NET) 9/21 and the launch will be NET 9/27. In that same article: 9/27 would put the battery period at 46 days. Space Force needs to start with the assumption that there is no FTS until demonstrated otherwise. So they could...
  38. .Scott

    Microsoft Technical Interview question

    As originally described, we were looking through a dataset -not just a list of integers. So it was unclear whether he was looking for a dataset entry - or just the collation (sort key) value. My description intended to handle both cases. So the table I was compiling would have looked like...
  39. .Scott

    Microsoft Technical Interview question

    I skipped over the "even record count" issue - only because it made the description difficult. So you are simply computing the median. So your histogram will simply be an array with 1000 counts. When you're done, count through half the records. If it's odd, just pick the histogram bin number...
  40. .Scott

    MHB What is the difference between activity and event in "simulation"?

    "Making a Deposit" is not an event. The events might be "New deposit record is available", "start of deposit creation", "deposit envelope received", "new deposit record serial number ready", etc. There may be dozens of milestone events that occur in the process of "making a deposit".
  41. .Scott

    Microsoft Technical Interview question

    From the problem statement, it is unclear whether the "middle value" refers to the entire median record or just the collating key of the median record. It is likely that they are presumed to be the same. The only problem with attempting to do this purely with a histogram is that the range and...
  42. .Scott

    Artemis 1 going to the Moon (mid November)

    Up until Sept. 17, it's been on the pad because the leak is at the Rapid Disconnect seals. They have needed at the pad to see the problem and repair it. It needs to remain there until the repair is tested (now scheduled for the 17th). If they get the FTS battery extension, it raises this...
  43. .Scott

    Artemis 1 going to the Moon (mid November)

    The FTS battery limit could be a problem. The original limit was 20 days based on the device spec. It was already waived to 25 days based on actual observed battery performance. Bumping it to 40+ days could be a non-starter. A visit to the VAB may be unavoidable.
  44. .Scott

    Artemis 1 going to the Moon (mid November)

    Per the 11am call: They need to comply with test range requirements. They are asking for a waiver to extend their FTS batteries retest requirements (to avoid the VAB visit). (batteries are mostly on the core stage - one for each "command receiver/decoder") Need to deconflict with DART mission's...
  45. .Scott

    Artemis 1 going to the Moon (mid November)

    From what I have read, the purpose in doing the work at the pad is to actually work the problem with the plumbing attached. The last I read about the schedule was like this one from livesciences: The recertification relates to the flight termination system. It expires because there are...
  46. .Scott

    Artemis 1 going to the Moon (mid November)

    It looks like: Set up shop at the pad; With the cryo plumbing available at the pad, explore and perhaps fix the problem; bring SLS back to the VAB for recertification; redeploy to pad; wait for a launch window and avoid conflicts with ISS launch activity.
  47. .Scott

    Artemis 1 going to the Moon (mid November)

    It's mostly a difference in tempo. When SpaceX RUDs, they already have the next one in the works. If NASA/Boeing RUDs with the SLS launch, it would literally take an [unlikely] act of Congress to recover. At this point, a real SLS setback would be not launching before Starship. Elon has said...
  48. .Scott

    MHB Logic puzzle: students, cities, subjects and grades.

    I'll get you started: In our universe, there are 5 sets, 5 students, 5 cities, 5 grades, and 5 classes. Each of the 5 sets contains 4 elements, a student, a city, a grade, and a class. 0.1) No element is share among the five sets. 1) None of the students come from the cities with the same...
  49. .Scott

    Artemis 1 going to the Moon (mid November)

    They have a launch window on Monday and Tuesday. After that, they would need to wait for at least 2 weeks.
  50. .Scott

    Comp Sci Please give me an example of how any indexing works in big data search

    I have corrected my spelling of "optimization", flashed out my point on that, and corrected those "crazy" cut and paste errors. Thanks!!
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