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I may not be a native English speaker, but Wikipedia tells me that "In commerce and industry, 24/7 or 24-7 service (usually pronounced "twenty-four seven") is s

by jhgb 5y ago

I may not be a native English speaker, but Wikipedia tells me that "In commerce and industry, 24/7 or 24-7 service (usually pronounced "twenty-four seven") is service that is available at any time and usually, every day ... Synonyms include round-the-clock service (with/without hyphens), especially in British English, and nonstop service". I struggle to fit "at some times during every hour" into this definition. If there's a 24/7 shop, I definitely don't expect not being able to enter it at some times, or even not being able to enter it 75% of the time.

Retric 5y ago
In practice it’s common to use similar terminology for intermittent services. For example a subway train might only be running every 30 minutes but it still lists hours of operation. The hotel help desk might not have someone there every second, but theirs a difference between someone putting up a “be back in 15 minutes sign” when their on a bathroom break rather than a closed sign when they are leaving for the day. Informally, the existence of a modest wait doesn’t preclude 24/7 service.
- jhgb 5y ago
  I definitely don't picture a 24/7 service as waiting up to 45 minutes every hour. By that time you're operating six hours out of every twenty four. You might not even be able to advertise yourself as 24/7 at that point in some places. > For example a subway train might only be running every 30 minutes but it still lists hours of operation. But that's a train. It never runs every single moment, so that doesn't make the times with once-per-30-minutes trains different from the times with once-per-10-minutes trains. On the other hand, if it's for example a grocery store, you definitely do expect being able to enter at any moment and purchase something if it advertises itself as "24/7" or "nonstop".
  - ben_w 5y ago
    As a native English speaker, I agree with your assessment of “24/7”; linguistics aside, the core point of the argument is (or should be) that ISS power cycle is 90 minutes whereas a moon base would be 28 days, unless you can get power from the sun side to the dark side. I’m unclear why the blog post is saying this is difficult, as it should be fairly straightforward to make aluminium cables in-situ and just leave them exposed on the surface, the atmospheric pressure on the moon is far lower than the minimum of the graphs on the linked Paschen's law Wikipedia page. (I’m not a physicist, there is a high chance I’m overlooking something any vacuum engineer would consider obvious).
    - jhgb 5y ago
      > whereas a moon base would be 28 days Actually it would be 29.5 days. If you're mentioning the cycle lengths, the ISS actually has it worse relatively to the length of its cycle than a south pole base on the Moon would have it since ISS can spend up to around 40% of its time in Earth's shadow whereas lunar night can be as little as several days long on some places of the south pole. And if you elevate the solar array by as little as several meters, I believe I saw some papers predicting a period without power as short as 2.5-3 days or so. So rather than a ~500:1 ratio of storage difficulty, it's at least improved to ~100:1 or so. Still fairly bad but not as bad as the simple cycle length ratio would suggest. The notion of connecting several places with cables is a nice one, and also a neat optimization problem. We should be able to calculate the immediate power curves in different places. Finding a minimum cost combination could be the topic for an interesting study. Long-term, this is definitely what you'd want to do.
  - Retric 5y ago
    > you definitely do expect being able to enter at any moment and purchase something if it advertises itself as "24/7" But what’s an acceptable delay before purchase. I have definitely spent more than 45 minutes waiting in the line for events etc while their currently open. It’s all kind of moot as it’s clear what I meant is exactly the underlying reality, but I can see why you object.

by jhgb 5y ago

Retric 5y ago

In practice it’s common to use similar terminology for intermittent services. For example a subway train might only be running every 30 minutes but it still lists hours of operation. The hotel help desk might not have someone there every second, but theirs a difference between someone putting up a “be back in 15 minutes sign” when their on a bathroom break rather than a closed sign when they are leaving for the day. Informally, the existence of a modest wait doesn’t preclude 24/7 service.

jhgb 5y ago
I definitely don't picture a 24/7 service as waiting up to 45 minutes every hour. By that time you're operating six hours out of every twenty four. You might not even be able to advertise yourself as 24/7 at that point in some places. > For example a subway train might only be running every 30 minutes but it still lists hours of operation. But that's a train. It never runs every single moment, so that doesn't make the times with once-per-30-minutes trains different from the times with once-per-10-minutes trains. On the other hand, if it's for example a grocery store, you definitely do expect being able to enter at any moment and purchase something if it advertises itself as "24/7" or "nonstop".
- ben_w 5y ago
  As a native English speaker, I agree with your assessment of “24/7”; linguistics aside, the core point of the argument is (or should be) that ISS power cycle is 90 minutes whereas a moon base would be 28 days, unless you can get power from the sun side to the dark side. I’m unclear why the blog post is saying this is difficult, as it should be fairly straightforward to make aluminium cables in-situ and just leave them exposed on the surface, the atmospheric pressure on the moon is far lower than the minimum of the graphs on the linked Paschen's law Wikipedia page. (I’m not a physicist, there is a high chance I’m overlooking something any vacuum engineer would consider obvious).
  - jhgb 5y ago
    > whereas a moon base would be 28 days Actually it would be 29.5 days. If you're mentioning the cycle lengths, the ISS actually has it worse relatively to the length of its cycle than a south pole base on the Moon would have it since ISS can spend up to around 40% of its time in Earth's shadow whereas lunar night can be as little as several days long on some places of the south pole. And if you elevate the solar array by as little as several meters, I believe I saw some papers predicting a period without power as short as 2.5-3 days or so. So rather than a ~500:1 ratio of storage difficulty, it's at least improved to ~100:1 or so. Still fairly bad but not as bad as the simple cycle length ratio would suggest. The notion of connecting several places with cables is a nice one, and also a neat optimization problem. We should be able to calculate the immediate power curves in different places. Finding a minimum cost combination could be the topic for an interesting study. Long-term, this is definitely what you'd want to do.
- Retric 5y ago
  > you definitely do expect being able to enter at any moment and purchase something if it advertises itself as "24/7" But what’s an acceptable delay before purchase. I have definitely spent more than 45 minutes waiting in the line for events etc while their currently open. It’s all kind of moot as it’s clear what I meant is exactly the underlying reality, but I can see why you object.