observantTrapezium

As it should be… Navigators could determine latitudes pretty accurately by using astronomy. It was the longitude that was a big problem (maybe that’s part of the reason Japan is placed in the middle of the Pacific).

I’m pretty sure I’m in my fourth pair now.

That may be relativists (they would actually measure anything in units of mass, with everything else defined through G = c = 1). Astrophysicists commonly measure mass in solar masses, long distances in parsec (or kiloparsec, megaparsec), short distances in solar radii or AU, and time in whatever is relevant to their problem (could be seconds or gigayears)

I’m sitting on an Aeron at work, it’s good, but I can’t in good conscience pay that much for a chair. I was recently on the market for a new office chair and extensively researched it. It really looks like it’s a hit or miss with every chair in every price range, and I was very seriously considering replacing my Hyken with another Hyken. I decided to go with the IKEA Markus and have been sitting on it for about a month. I’m only moderately happy with it, may even return it before the year is up although I’d hate doing it.

That is almost certainly Staples Hyken. Comfortable chair but cheaply made, mine started disintigrating in a couple of years.

Playing 4D chess /s

EM and gravitational waves are seen as analogous because as I wrote, they are produced by acceleration of charges and masses, respectively. The physics behind them is very different (described by Maxwell’s equations for EM and Einstein field equations for GW), but all systems that have waves in them (including sound in the air, waves on the surface of water etc.) can be approximated as linear for small perturbations, which means that they satisfy the wave equation at that regime.

They are quite similar to electromagnetic waves, but also quite different. They are produced by masses accelerating (just like EM waves are produced by charges accelerating), and indeed cause orbital decay. But this orbital decay is only important in relativistic systems (so the Earth, which is orbiting the sun at 0.0001 the speed of light, is not going to fall into the sun because of gravitational waves).

See my response below to Captain Aggravated about how dilute those large stars are.

It’s an interesting question whether anybody would actually feel spaghettification 😁 I actually don’t know. You can use physics to calculate the proper time derivative of the tidal forces, but you need biology to define the start (and end…) of the process. My intuition says that it probably happens too fast, so once the tidal forces are strong enough to be perceptible, they grow strong enough to rip you apart before you realize (again, just a hunch).

Yes, but red supergiants differ from the sun in that their photospheres are extremely dilute and don’t have a sharp transition to the corona. I don’t know the details of this particular star but take Betelgeuse as an example (it’s probably not particularly large for this catrgory), it’s radius is ~640 the sun’s per Wikipedia, which gives a volume of ~260 million that of the sun. But it is only x15 times as massive as the sun, so on average ~20 million times less dense.

Yep, you got it right. The accretion disk is actually really flat. Those images are produced in simulations that take into account the curved (and very complex) paths light takes in the vicinity of a black hole. These images really depend on the angle between the line of sight and the disk.

In the case you are unlucky enough to encounter the black hole “heads on” and fall into it radially, the proper time timescale to spaghettification is the size of the event horizon divided by the speed of light. The most supermassive black holes will have a horizon of around one light day, so that’s what we’re working with, a matter of days. If you come in on the most tangential orbit possible though, I guess you’re buying some time but I’ve never heard that it’s supposed to take many years of proper time (I doubt that claim a little bit, but haven’t calculated myself).

Astrophysicist here. Yes, space is crazy, but interesting things to keep in mind:

1. The size of a star is determined by something called the photosphere. With those extremely massive stars, you can be hundreds of millions of kilometres “inside” and not yet know it.
2. Similar story with supermassive black holes, from the perspective of an astronaut falling in, they wouldn’t really be able to tell when they cross the horizon because the tidal forces there are very small (they will inevitably fall towards the centre and get spaghettified at some point)

QWERTY on a cheap Dell keyboard I’ve had for 12 years.

I’m sure some of the alternatives are objectively superior, but with all due respect to enthusiasts, I’m simply not passionate about it and have yet to be convinced that the time and pain spent on getting used to a new layout would actually be worth it in the long run.

Haha, that’s right. Immediate noticed that.

I think younger people in Canada only know °F if their thermostat is set to it and they can’t or don’t bother to change. My stupid fridge is in Fahrenheit and that can’t be changed (even though the handbook shows the display in Celsius! A variation of the model is probably sold abroad).

I think Canada properly adopted Celsius, kilometres, litres and millilitres (at least here in Toronto), but all other metric units are the underdog. Even CBC, that is probably the only media outlet that tries to stick to metric will specify people’s height in feet and inches. Shameful.

Interestingly, that is not the case. Month names can differ in different languages. I discovered the hard way that Ukrainian has completely different names for months when I had to connect to a Linux machine in Kyiv with Ukrainian locale (I can read Cyrillic, but the abbreviated month names meant nothing to me). The name for August is “serpen” by the way, and it is similar in some other Slavic languages. Also Arabic has its own month names based on Akkadian, August is “ab” but an Arabized version of the word August is also commonly used and understood. Finally, in Mandarin and presumably other Chinese languages, Gregorian months are only referred to by their number, so we are in “bayue” (lit. eight(th) month).

The start of the calendar has to be arbitrary, there’s no way around that as it’s not feasible to measure the time since the beginning of the universe with good enough accuracy.

As others commented, the Julian Day is a time measure that is actually used in astronomy, and Unix time is a time stamp standard (not really a calendar, although it could be if we got used to it) that is mostly a way to store time points, not really to consume them before converting to a more readable form.

But as a scientist who is wholly irreligious, I’m not overly bothered by using the Gregorian calendar, even though it has Christian (and a lot of pre-Christian) elements. Its annoyances (different numbers of days in each month, weeks not aligning with years, leap years etc.) are due to the fact that we decided to measure time in these arbitrary units. At least it’s universal in the modern era (often in conjunction with another calendar), and everywhere you go people understand what “August 5, 2024” means (although August might have to be translated to the target language, since the names of the months are not universal).

That’s more than you can say about non-time units of measurement (I’m looking at you, imperial and US customary units!!)

Digital only. Who even has room for physical books.

Have autoplay disabled