Nikolai

Are they running 1.4.1 in this stream? If so, the bug where the tops of the depictions in the top row of parts (as seen in the side menu in the VAB) are cropped off is still there. EDITED TO ADD: Yes, it is -- I just saw the introductory splash screen.

I meant to refer to the weight Bullock's exhausted hand was taking. Of course, if you go back to the multiple exposure or the clip, you can see that she wasn't the center of rotation, either... which lessens the weight on her hand as well as the angular displacement she has to go through. I tend to think Clooney was rotating much faster than that 5 deg/s, though, if you watch the stars in the background during the close-ups; I suspect that that's because the station was rotating some amount itself, possibly because it had some initial non-zero angular velocity after being abandoned (which seems likely; what are the odds that it was left at exactly zero?) and/or possibly because some angular velocity was imparted to it by Clooney's and Bullock's interactions with it. But these seem like trifles. From one point of view, attempts to punch holes in this scene seem like attempts to make petty complaints; from the other, attempts to defend this scene seem like attempts to imagine things that aren't there. Since space is a place where motion can be deceptive and counterintuitive to senses honed with long experience on Earth, maybe I gave it more credit than it deserves. Or maybe things that seem poorly-shot are a matter of subjective taste. Or something. I have to admit that this particular bit didn't break my mimesis, though; even seeing it in the theater, I thought they were rotating right away and that Clooney was in trouble. I also tend to see switching back-and-forth between close-ups less as sequential and more as "Here are the expressions the other person was making while the camera was looking away", for whatever little that matters, and maybe that factored into the duration of the scene bothering me less. (What did break my mimesis was the station-hopping. But then, I guess, you'd have a much less engaging story, or at least a much less lengthy one. "One day, debris hit the Shuttle in the middle of a servicing mission. Every crew member died. The End." Ninety minutes between debris encounters also seemed pretty bogus.) (P.S. Apparently, the mass of a dry MMU was 136 kg, if that helps with figuring out the force on Bullock's hand; we'd have to add that to the mass of the EMU and Clooney. So 350 kg total? )

That seems drastically small, considering that Clooney is wearing a spacesuit. The Shuttle EMU alone massed 115 kg without an occupant, and Clooney had his magic thruster pack on top of that. Add Clooney's mass to that -- let's say 250 kg total, just to be generously small. That brings us to 95 N at 5 deg/s, about two and a half gallons of milk held by one hand. It's not trivial to exert that kind of force, especially when you're drained from adrenaline and oxygen-starved and maintaining a grip in a spacesuit against vacuum -- and you've already been on EVA for several hours. (Story Musgrave will happily tell anyone who will listen how quickly EVAs can become exhausting, especially trying to maintain a grip, even with much smaller forces than this.) Honestly, she sounded kind of groggy and sluggish even while servicing the panel on EVA before the real action got started. Because he saw that the lanyard around her foot was slipping. That's pretty clear in the movie, too -- there are several shots directly on her boot with the lanyard slipping before he grimaces, decides to unhook himself, apologizes, and lets go. For me, it's the feel. They got the feel of space right -- it's not like being submerged in water or like anything we're familiar with. It's alien. And that alien nature is what will kill you if you don't watch out. That said, I think the movie gets a lot more grief than it deserves. True, there are a decent helping of things that they got obnoxiously wrong, but they clearly tried, which is a lot more than I can say for a lot of other "space" movies.

... and in that clip, you can actually see the rotation between 2:15 and 2:19 if you're watching for it. The only shots I see that show orientation with respect to the planet have Bullock in the frame, and she's much closer to the center of rotation and doesn't move a whole lot. Plus, you know, it's a long tether. And it's hard to determine how the axis of rotation lines up with views of the planet below (perspective is hard in this scene, and in space generally). I can't contest that, because a lot of people seem to miss that it's there. Still, it seems to me that the fact that the force is there should be the sort of thing that makes people look for what they might have missed if they can't find it, not flatly state that there's nothing. Are you sure? Such a rotation would be very gentle, as we've discussed. Also, it's not the only way to pick up rotation. If you speed towards the end of something much heavier than you are, and give yourself a kick in some random direction as you leave, but are restrained to the end by a tether, you'll pick up rotation. (So will the heavy thing, but much less noticeably so.)

He was rotating. If we superimpose several screen captures, you can see that clearly. (That doesn't mean that the orbital mechanics of the movie wasn't garbage, of course. It's just that this particular objection has a fairly mundane explanation.)

No, it's not the stuff generated by hype while waiting for another version of KSP to drop. Apparently, scientists have just discovered a form of matter that was only hypothetical for fifty years. From what I've been able to gather, here's the basic idea: When electrons leave valence shells, they leave "holes". The "holes" are considered to be positively charged(*). "Holes" and electrons even attract each other; they act exactly as if they're positively charged particles. Excitonium is matter made up purely of electrons and "holes", held together by their mutual charge. There are no atomic nuclei. An "exciton" is an atom without a nucleus; excitonium is made up of excitons. --- (*) Just ask an electrical engineer. "Holes" are considered to be the charge carriers in semiconductors, which are electronic components of everything from diodes to transistors to microchips. The math works out the same as it would if we tracked electrons instead (the "real" charge carriers in circuits); the only difference is a change in sign.

Well, right, and you can see that if you take the time to simplify the expression of force on the ball into a constant times the distance of the ball from the center -- which is a spring equation. Springs follow sinusoidal motion. (The "spring constant" is equal to m*g/r, where m is the mass of the ball, g is the acceleration felt by the ball at the height from which you drop it, and r is the radius at which you drop the ball.)

Not only that, but the time it takes to get to the other side is exactly the same as it would take for the ball to orbit to that point at that altitude. Either way, the time to get to the other side is pi*sqrt(r/g), where r is the radius you drop it from and g is the acceleration due to gravity at that radius. I can do the math if you like.

Yes, possibly, but not because the Sun is going to go supernova; it's not massive enough for that. Some five billion years or so hence, the Sun will turn into a red giant. Its radius may grow large enough to swallow Earth. https://www.universetoday.com/18847/life-of-the-sun/

Sorry to be a troublemaker, but as usual, it's not that simple -- especially if we're talking about selecting a species' tendency to be social. That involves both natural and artificial selection, especially if we're talking about a tendency towards altruism.

Oh, I don't contest that the distinction is useful. It often is. It's just not the case that the boundary between the two is always clear. Well, there, again, we have a gray area. The modifications themselves are not selected, but the genes of the one who received the modifications (as a result of her own will or not) are selected for reproduction over someone else's. There's still selection going on, even if it's not selection of genes that would directly give rise to certain traits deemed attractive. I don't think it's that clear. The attraction I mentioned included neither posture nor body chemistry; you read those into my description somehow. I explicitly mentioned the attraction came as a result of modification to an individual's appearance.

Yes. (In all seriousness, the boundary between natural and artificial selection is far from sharp. For example, if you find an attractive female in appearance, mate with her for that reason and produce offspring, is that natural or artificial selection? What if her appearance has been altered -- she's preened her feathers, for example, as part of a strategy to attract mates? What if that alteration is done by a third party? Does it matter whether that third party performed that alteration on purpose or not, or what the specific goal of that alteration was -- whether attractiveness was the intent or the by-product of some other process? And so on.)

If you're close enough to the center of the disk to encounter gravity normal (perpendicular) to the surface, you're bound to find a surprise as you fly away. The gravitational force of a sphere falls away as 1/r2 from the center of the sphere; the gravitational force from an infinite disk (and the disk is "close enough" to infinite to act pretty infinite before you put some appreciable distance between you and it(*)) falls off as 1/r. In other words, you'd find it harder to get away from a disc than to get away from the surface of a sphere. I can do the math if you're interested. --- (*) This is a pretty common trick in physics. Sometimes, the math is easier if you pretend a surface is infinite. The electric field of a capacitor can usually be modeled by an infinitely-large plate where the charges on it are distributed uniformly; the math is much easier, and the results you get are "close enough" to real life.

Assuming that it was a close encounter of the third kind (face-to-whatever contact), and assuming that I had the wherewithal to think clearly, I'd ask for evidence that I could take with me that he/she/it/they was an interstellar visitor. It wouldn't have to be any kind of super-technological artifact, even -- I'd be content with a rock with no evidence of meteoric heating that unambiguously dated to eight billion years old, for example. I have to admit that it would be relatively easy for me to dismiss close encounters of the first and second kinds as tricks played on me by my senses.

Every five hours, actually. But still, very cute, Mr. Clarke.

This interloper has been dubbed Oumuamua, which means "first messenger" in Hawaiian. We also think we know roughly where it came from (the Carina and Columba Associations), meaning that we have some idea of how long it's spent in interstellar space (40 million years) and can constrain the mass of the planet that flung it our way in the first place (from a "super-Earth" to a gas giant 20 or 30 times the mass of Earth). It is expected that when we finish the Large Synoptic Survey Telescope in Chile, we will discover objects like this at a rate of one per year or so. https://arxiv.org/abs/1711.01300 https://arxiv.org/abs/1711.01344

We live in the largest supervoid known to science (the KBC Void), a region about two billion light-years in diameter. The Milky Way is within a few hundred million light-years of the center. EDITED TO ADD A SOURCE, SINCE IT'S ALWAYS A GOOD IDEA TO HAVE THEM: https://www.space.com/37191-we-live-in-a-cosmic-void.html

Last week, an asteroid was discovered with the provisional designation A/2017 U1. It's about 400 meters wide. What makes this exceptional is that it's an asteroid from another star. There are plans to measure its composition as it goes by. (It's moving too fast to be bound to the Sun.) We don't know which star it came from, exactly, but its angle of approach shows it coming from the galactic plane -- where most of the stars in the area are located. It probably spent millions or even billions of years in the interstellar dark before coming close to us, and after swinging by, will be consigned to interstellar space for millions of years more. http://www.ifa.hawaii.edu/info/press-releases/interstellar/

I've already thanked you guys for making such an awesome game and for getting my kids to understand and enjoy some of the nuts and bolts of space exploration. I'd also like to thank you for the insights you've provided into software design, and for even designing your widgets and editing tools such that my foray into 3D editing and animation software has enjoyed a much shallower initial learning curve. Your little project has improved my quality of life, and it's not often that a game gets credit for doing that.

This is a bit of an unusual request: I have an online friend who says that her father (who passed decades ago) might have been one of the divers from the USS Hoist when she served in the recovery flotilla for Gemini 4 in 1965. Does anyone know of any civilian-accessible resources that might be able to confirm or deny? She'd really like to be able to come by some video footage of the event, if any exists.

Steins;Gate, followed closely by Planetes, followed closely by Cowboy Bebop.

Whippersnapper. I remember when Pluto was just a point, before it even had a moon.

Truth. A nuclear explosion detonating near an asteroid's surface doesn't "push" the asteroid with a shockwave so much as emit enough X-rays to boil off a decent amount of asteroid material, and the reaction to the mass boiling away "pushes" the asteroid in the opposite direction. Also true. Rock is surprisingly resistant to being vaporized. And nukes are powerful, but not magically powerful. You need somewhere on the order of ten gigajoules delivered to a cubic meter of rock to vaporize it. http://www.madsci.org/posts/archives/mar2002/1015040902.Es.r.html

Yup, yup. And without engineering, science is just another kind of philosophy. Like I said, ongoing debate. =shrug= I guess this is all tangential to the point anyway, which is that space exploration is done to eventually put people in space, and we kind of seem to agree on that. Where people fall on this particular point doesn't really matter with respect to that. That particular point wasn't unclear. My question is why you felt the need to point out specifically that it was circular, not what your point was. But that seems kind of academic, really -- I genuinely think we agree about much more than we disagree about.

I'd have to go with The Avengers (the Diana Rigg years, specifically), Star Trek (the original series), Leverage, and Steins;Gate. And Sledge Hammer! was indeed awesome.