Thursday Throughput: Units of Measure Edition
[ThTh1] This article is a few years old, but was brought to my attention this week. And since it concerns a subject dear to me, I thought I’d give it a go. It’s one of the more recent dispatches from the annals of Physicists telling Astronomers How We Can Do Our Jobs Better:
In a paper published April 1 in Astronomy & Geophysics, Keith Atkin, a retired associate lecturer in physics at the University of Sheffield, UK, argues that while the professional field of astronomy has moved away from the imperial units of miles, pounds, and degrees Fahrenheit, “this transition has not been complete,” according to the abstract of his paper. The use of units of measurement such as light-years (the distance light covers in a year: 5.88 trillion miles [9.5 trillion kilometers]) and astronomical units (abbreviated AU, the average Earth-Sun distance: 93 million miles [150 million km]) persists, he says, when “simpler logical units would help both within the subject and in multidisciplinary research.”
…
In the paper, Atkin first focuses on units of distance measurement, noting not only the seemingly random and often redundant nature of units of measurement unique to the astronomical field, but sometimes their completely strange construction as well. “My bête noire is the megaparsec — a clumsy and ugly fusion of an SI prefix and a non-SI unit,” he writes.
His solution? “To encourage the use of SI units of length in all astronomical work: all distances and lengths should be based on, and simply related to, the metre. The metre is defined as the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.”
Thus, he argues, all units of astronomical distance, from the AU to the parsec (equivalent to 3.26 light-years, and derived from the apparent motion of nearer stars against the background that occurs as Earth orbits the Sun), can really be expressed in meters, with the appropriate SI prefix attached.
…
Atkin expands his argument to other units of measurement — why use kilograms or solar masses (the Sun’s mass, 1.98 × 1030 kg, is equal to 1 solar mass, and the masses of other stars can be measured on this scale, such that Betelgeuse is almost 8 solar masses) when SI prefixes and grams will do? He suggests that the unofficial prefix besa (1033) be used, such that the Sun is 1.98 Bg and Betelgeuse is 15 Bg. Similarly, the electron volt (eV), which measures the energy of particles in both astronomy and physics, could instead be expressed in terms of attojoules (aJ, 10−18 joules).
He also argues that units such as arcminute and arcsecond should be done away with, though admits that “the degree is presumably here to stay.” Atkin proposes measuring all angles in terms of either decimal degrees or radians, rather than using degrees, arcminutes, and arcseconds, as astronomers do today.
My response to this can be most easily summarized by Dr. Evil:
The editors, unfortunately, insisted that merely posting a YouTube clip did not, contractually, count as a Throughput. So I’ll expand on this a bit. Because this is a question I get asked sometimes and it’s worth going over why astronomers measure things the way we do (with the caveat that sophisticated calculations actually do use SI units).
The universe exists on unimaginably vast scales; scales that dwarf human comprehension. Hell, just our solar system exists on an unimaginably vast scale. In describing the grandeur and scope of the universe, units intended for the human experience — meters, kilograms, liters — are simply not up to the challenge. And so we use units of measurement that, while not as “scientific”, make the universe comprehensible.
If I tell someone that the Andromeda Galaxy is 20 zeta-meters away, that means nothing to them. It’s just a lot of zeros. But if I tell them that it takes light nine minutes to reach from the Sun and two million years to get to Andromeda … that can give them a glimpse of just how vast the universe is. If I tell someone that Betelegeuse weighs 15 “besagrams” that means nothing. If I tell them it’s 15-20 times the mass of the Sun, that means something. “Astronomer units” are designed to make the universe at least scaleable if not comprehensible.
Are these unit arbitrary? Perhaps, but SI units are arbitrary too. The meter was originally based on the swing of a pendulum in Paris and later tied to the size of the Earth and then a platinum bar and eventually light. The kilogram is based on the mass of a liter of water but the liter is based on the centimeter. In other words, the entire metric system is based on a few French toffs farting around in the 18th century. They didn’t descend from the heavens in a golden chariot. We just set these units of measurement to what they were because they were useful — for Earthbound endeavors.
But there’s another and perhaps more important reason why we use these units. One of the defining elements of astronomy is that we can’t touch the things we study. We can’t interact with them. All of our measurements are indirect. We can’t actually get a tape measure and plumb the distance to Andromeda. We can’t get Betelgeuse on a scale.
What astronomer units do is allow us to measure the universe in a sense relative to things we can measure. The standard unit of distance is the parsec. What is the parsec? Is it the distance at which an object has a parallax angle (a shift in its position as the Earth orbits the Sun) of one arc-second. Which means it is exactly 206,265 times the distance between the Earth and the Sun. Every distance in astronomy is therefore linked to the Earth-Sun distance, something we can measure in, literally, 20 minutes. Many of the distances in astronomy are uncertain because most of the universe is too far away for us to triangulate using the Earth’s orbit as a baseline. We have to make comparisons to things we can triangulate. And that all falls back to the parsec. It is the entire basis of the astronomical distance scale. Parsecs are meaningful to astronomy in a very real and tangible sense. Meters are not.
The same goes for other measurements. We can measure the mass, radius and brightness of the Sun directly. Therefore we scale everything to that standard. Isn’t scaling things to the Sun more meaningful and sensible than scaling things to some dusty old bar in Paris and a big gulp of water?
I certainly think so.
[ThTh2] The story of how women came to be excluded from the space program is an interesting one. In the early days of the space program, 19 women volunteered to be part of the astronaut corps and 13 of them passed the qualification tests. NASA, however, went with an all-male astronaut corps. Sexism no doubt played a role but the biggest reason was that, in the 1950’s and 1960’s, the astronaut corps was seen as an extension of the military. All seven of the Mercury astronauts were military pilots. All ten of the Gemini pilots were military. Neil Armstrong was technically a civilian, but was a military veteran. The first non-military astronauts was not selected until 1965 (and four of those were veterans). Harrison Schmidt became the first true civilian in space when he flew on Apollo 17 in 1972. It would be a decade later that Sally Ride would become the first American woman in space.
Which makes this aspect of last week’s Blue Origin flight all the more satisfying. Wally Funk was part of the “Mercury 13”, the women who passed the Phase 1 testing but were excluded for the astronaut corps. At age 82, she was Jeff Bezos’ guest on the flight and finally got into space.
[ThTh3] And speaking of space flights, there’s been some sparing over where exactly the boundary is that defines “space”. The difference between the two is … not really meaningful.
[ThTh4] Nice demonstration of how we’ve gotten to now our most distant planet.
Views of Pluto through the years! pic.twitter.com/mxbrx039Cz
— Universal-Sci (@universal_sci) July 17, 2021
Yeah, I said it.
[ThTh5] Why does it seem like the vaccines create better immunity than COVID itself? This Twitter thread digs into it.
[ThTh6] An interesting look at how a grad student prank became a conspiracy theory.
[ThTh7] Ivermectin is the latest “miracle cure” being touted for COVID-19. It now looks like the study supporting its uses was a fraud
[ThTh8] A couple more fun Twitter threads for you. The first is on why the claims that the vaccines have graphene is hot nonesense. The second is something for our West Virginia peeps: the paleontology of the Appalachian mountains.
[ThTh9] The headlines scream that the moon is going to cause massive flooding. What’s the reality?
I’ve written before about the tides and how they can vary depending on the alignment of the Sun and the Moon and Earth. Well, it can be a bit more complicated than that. The moon has a long precessional cycle around the Earth of about 19 years. The changing alignment of the Moon and Sun means that the size of the tides varies by about 3 or 4 inches over the course of that cycle, with low tides being lower and high tides being higher. Right now, we are at a low point. But in a decade that will be a highpoint. When you combined this with the inch-per-decade sea level rise due to global warming, that might result in unprecedented flooding in low-lying coastal areas. It’s hard to know exactly how bad it’s going to be. But it will be a peek at the world might look like by mid-century if we don’t get a handle on global warming.
[ThTh10] And speaking of global warming, shutting down nuclear power plants doesn’t get us closer to zero carbon. Just the opposite.
[ThTh11] Jane Coaston’s podcast had a debate on the wisdom or folly of attempting to contact alien civilizations. My view?
I find Dr. Kaku’s argument that broadcasting our existence to the universe risks annihilation to be extremely shaky. He falls back on history and sci-fi tropes a lot. But history tells us little about what such an unprecedented encounter would look like and sci-fi is usually just a way of retelling history in a different setting. If there are aliens out there, they are so far away, the resources they would have to expend just to reach Earth vastly outstrip whatever they would hope to gain by conquering us. His contention that Darwinian notions apply to interstellar contact crosses me as specious. A civilization that can travel between planets is definitionally a post-scarcity society, with energy and resources that are effectively unlimited.
This taps into one of those sci-fi tropes I despise: where the aliens invade us for our resources. Why on Earth would they do that? Earth is tiny; the universe vast. Even if they came here, why would they want, for example, our water? Jupiter’s moon Ganymede alone has more water than the entirety of Earth’s surface! Energy? The energy output of the entire globe would pale in comparison to an interstellar ship would use.
The only reason any alien would want to come to Earth is because of us. That would mean they are either so xenophobic, they’ll burn vast resources to just wipe out another species; or they are benign enough to just pop in and say hi. Either way, we have little choice in the matter. Dr. Vakoch may be overly optimistic about the potential benefits of contacting aliens. Again, the vast distances makes it unlikely to be worth their while. But he does make a good point: if they’re looking for us, they’ll find us no matter what we do. Even if we shut off our radio signals … they’ll know what to look for. We know what to look for and we aren’t super-advanced aliens. So actively trying to contact them poses no downside, even if the upside is also minimal.
Of course, having typed that, I’ll probably wake up tomorrow to find the aliens have arrived and blown up Congress. Of course … that may not necessarily indicate hostility …
I very badly want there to be extraterrestrial life, and very badly want human space exploration to happen.
But I’ve grown more and more resigned to the idea that space travel for humans just is like Fetch, just not going to happen.
I’m partial to the arguments that the environment of space is so incredibly hostile, and the commercial value of other planets is so paltry that it will never be commercially viable to have for example, mining colonies on Mars or whatnot because the costs and energy required just to sustain life there would always outweigh whatever value is mined.
In addition, the advances of AI and robotics seem like it would be far more efficient to have robotic probes and machines operating which don’t have the complex needs that humans do.
As for alien life, I think it is much the same- Its hard to imagine a form of life that is conducive to space, and as Michael points out, the species that has enough recourses to travel between stars probably doesn’t need to do so.Report
It really comes down to, how do we get out of the gravity well? As long as the cost/kg of climbing out of the gravity well is high, you are right.
If that cost becomes reasonable, however…Report
Isn’t the bigger problem exposure to cosmic radiation?Report
If I can lift mass at a reasonable cost, then no.
There is very little radiation out there that I can not shield against, given sufficient mass budget. I was actually just reading about a very interesting fungus here on earth that just loves itself some cosmic radiation, and a 20cm layer of it could effectively shield a station from all the radiation it would normally suffer. Water is another handy radiation shield.
But man, lifting that much mass right now, that would be pricey.
Honestly, the lack of gravity on our bodies is really the largest hurdle. Our bones start to lose mass almost immediately once gravity is not acting on them.Report
Wow, that fungus thing is interesting. I know in Kim Stanley Robinson’s Mars trilogy the colony ship used water, but, like you say, water is really heavy.Report
Cordwainer Smith used oysters.Report
Holy smokes, I’m stealing that fungus idea for a story. What a great discovery!Report
I think this is it:
https://www.technologynetworks.com/applied-sciences/videos/chernobyl-fungus-eats-nuclear-radiation-via-radiosynthesis-338464Report
20 cm? Golly jeepers. That’s… (holds both hands out in front of him, touching)
That’s a lot of cms.Report
In space, not so much.Report
I was thinking about between the (space thing) and the vacuum.
Say what you will about the space shuttle shielding, but it was 1-5 inches.Report
Right, and that was a lot, because you had to account for those dimensions and mass on a thing that had to lifted, and glide back to earth.
If I’ve got a permanent space station and the ability to lift mass at a reasonable price, my perspective on what counts as ‘thick’ shifts considerably towards (or beyond) “20cms ain’t nothing!”
ETA: I mean, if you can provide shielding using a thinner space between hull plates, great! But filling the empty space between hull plates is largely free when the thing doesn’t have to fly through atmosphere.Report
Wait, can take it out there and seed it and it can grow out there?Report
Possibly, depends on how fast it grows and what kind of growing medium (food, structure) it needs. If it’ll take 20 years to fill the walls, we’ll need to haul it up. If it take 2 years, we’ll probably still be building out the interior by the then.Report
Okay. That turns it from “that’s a lot” to “maybe it’s not?”
I suppose I’d need to know how dense the fungus would be. If a liter of food results in 12 liters of fungus… that’s a pretty good tradeoff.Report
Also depends on the definition of “food”. If the fungus is happy to use cosmic radiation to turn human waste into radiation shielding, well, then you are already lifting all the fungus food, just needs about 12 hours of biological processing before feeding it to the fungus.
And if it doesn’t… we are getting awful good at tweaking the genomes of single cell life.Report
Yeah, some gain-of-function research on some fungus that eats radiation and poop.
What could possibly go wrong?Report
Pessimists…Report
Honestly, the lack of gravity on our bodies is really the largest hurdle. Our bones start to lose mass almost immediately once gravity is not acting on them.
And as the time in micro gravity increases, assorted problems with fluid distribution show up, affecting vision, cardiovascular health, and neurology. I’ve seen at least one report from someone who summarized the last as “it’s beginning to look like sustained micro gravity makes humans stupider.”
If I can lift mass at a reasonable cost, then no.
Whatever else we might want to say about Elon Musk, he’s doing rocketry design to reduce the cost to LEO or lunar orbit. On the other hand we have the United Launch Alliance whose large effort is to build a single-launch, minimal mass to the moon and return, $2B per launch boondoggle. If I had the authority, I’d be looking for whoever approved letting ULA reproduce Apollo with better materials and fire all their butts.Report
Yep, we evolved in a gravity well, thus we must exist in one, or something that mimics one.
Musk is a hot mess, but SpaceX is doing good work.Report
Yep, we evolved in a gravity well, thus we must exist in one, or something that mimics one.
If I were pinning my hopes for the human race on space colonization of some sort, my first two questions — which are, I think, completely unanswered currently — would be: (1) how many humans does it take to support a society at our current level of tech or somewhat higher; and (2) what’s the minimum continuous acceleration necessary to grow a human from zygote to adult?
My entirely unscientific guess for the first is between three and thirty million, depending on how good the automation is. Most people seem to think a lot smaller than that. I think that’s because they think about a small number of people at the top, but not how big the pyramid is that supports those people.
If the answer to the second one is 5.0 m/sec², then most of the plans are screwed. No matter where you go, you have to build centrifuges capable of supporting a sizeable fraction of the population (and see the previous paragraph) on a continuous basis.
And to borrow an idea from one of Chip’s comments, the worst case scenarios for climate change (or ecosystem collapse from other causes) mean colonists have a very limited time frame to get to where they’re not dependent on Earth being a functional high-tech world.
Yeah, I’m a pessimist these days.Report
” On the other hand we have the United Launch Alliance whose large effort is to build a single-launch, minimal mass to the moon and return, $2B per launch boondoggle.”
Again, in defense of NASA, Congress keeps shutting down their plans every 4 years and giving them new ones.
It’s amazing they can do ANYTHING as, by my count, the shuttle replacement has been authorized, fully cancelled, and everyone laid off at least three times. Possibly four.
All work lost, employees gone to other jobs, etc.
And not because NASA hated the idea of a shuttle replacement, but because Congress uses it as a political football.
If Ford was tasked with designing a car, then that was cancelled and told an airplane, then that was cancelled in back to a car but a truck this time, then that was cancelled and then it was an EV 18-wheeler (with at least a year to three years between new ideas), and someone asked “Why has it cost billions and ten years and you don’t have your EV 18 wheeler” I’m pretty sure Ford would snap.
NASA would absolutely like to make a cheap cargo rocket. They keep trying. And then all their money is taken away, their engineers fired, their work scrapped — and then two years later they’re given a new task, a new rocket, just different enough that 99% of their previous work is wasted — not that anyone who worked on it is STILL THERE.Report
This is why I never had a desire to work for NASA doing rocket design. Some of their aero labs are interesting, but that’s it.Report
This is exactly something I am wrestling with in my new novel. And I think I had a breakthrough last night. Hopefully will be able to share it with you in the next five years or so.Report
I wrote this some years ago.
https://ordinary-times.com/2014/03/05/space-the-final-frontier-why-do-we-care/Report
ThTh7: Why peer review is so important.Report
The alien threat scenario that seems most plausible to me is that it may be possible to build interstellar kinetic impactors — ships powered by fusion or antimatter or whatever that can accelerate to a significant fraction of the speed of light, coast across the space between the stars, and slam into planets hard enough to kill them.
Even now, we have vague ideas about how such weapons might be built. And if we can do it, aliens can do it. And the aliens will know we can do it to them. Unless they do it to us first. It wouldn’t be a war of conquest but of total annihilation. And it only takes one really paranoid civilization.
And high-velocity interstellar spacecraft, which are probably kind of difficult to build. Still, I wonder if the first sign of extraterrestrial life will be a bright flash on the horizon and a fireball erupting into the sky…Report
If the only interaction possible between planets is to attack one another, because travel would be impossible, it seems like there would be no reason to bother attacking, I guess that is where the paranoia comes in though. The other civ might be crazy enough to do it, just because they think you are crazy enough.
The Remembrance of Earth’s past series (which I think I was introduced to by a post here) deals with this very issue.Report
Yeah, it’s the logic of the Cold War. If either the United States or the Soviet Union had become confident that they could launch a first strike that would destroy all of the other side’s missiles in their silos, I’m not so sure one of them wouldn’t have done it.Report
Targeting would be pretty difficult. After all, we have to do various course corrections for our interplanetary probes, but the margin of error there is way less than for something interstellar. Moreover, at near-luminal velocities, it would take a lot of energy to retarget as the payload got near to its destination.Report
Will our nearest intelligent neighbors have picked up original broadcasts of The Honeymooners by now and concluded that we could send women to the moon?Report
“It appears to come from a primitive planet where sitcoms are still in black and white.”Report
Aliens could reasonably want our planet for the same reason we’d want other planets. The Earth is in the goldilocks zone (not too warm or too cold), it has decent minerals for a civilization, etc. If the Earth didn’t already have life it wouldn’t be hard to terraform it into working for us.
One of the best ways for us to expand is to send robot ships to other planets, terraform them, and then grow people there so they can create a civilization. This defeats the distance problem and the time problem.
As things stand now we’re on course to take over the Galaxy in a few million years. If someone else has already started that, we might have a robot ship show up here and then we’ll see what it’s owners think of ethics.Report
I suppose so, but wouldn’t an alien civilization capable of “reaching out and touching us” already have the tech to build habitats in space (with the near limitless resources of space already out there to use to do so). So of what use would our alien world with its gummy mess of complex microbial life really offer to them?Report
Depends on how much population pressure there is an how many liquid water planets there are at about 1G? Given enough pressure, and enough scarcity, scrubbing a prime bit of real estate clean of the locals might be a reasonable thing.
I mean, we did it.
ETA: The thing to keep in mind is aliens are, well, alien. We have no hard evidence that life must evolve on liquid water planets that have a gravity of 1G. Maybe we get too much sun, or have way too much atmospheric pressure, or too little, etc. We can’t assume we have prime real estate for other species.Report
Increase the gravity much past where we are and they don’t get off the planet or chemical reactions seriously change. Decrease the gravity much and the air leaves the planet.
Now throw in different chemistries or ice planets and it might get very weird… but we’re not sure if different chemistries are possible and it’s also not clear an ice planet can reasonably get technology (it’s implied there’s no opposable thumb and no fire).
The big problem with this reasoning is we lack information and we might be the weird ones for liking this temp gravity, etc. There might be an easier way to get life so we’re the likely odd ones out.
We won’t know until we do a ton of exploring and find out what experiments mother nature has run.Report
Yup!
Thus, I try not to worry about aliens. Humans and space rocks are already enough of a threat to humanity.Report
I guess? But sterilizing the Earth enough to get rid of the entire microscopic biosphere strikes me as very cost prohibitive and I am imagining that aliens would probably not want to be swimming in Terran microscopic lifeforms for heath reasons.Report
Maybe, or maybe they just want to get rid of the local life intelligent enough to object vigorously to their taking over.
Too many assumptions, not enough data.Report
My non-scientific WAG is we’ll get the tech to build robots which can visit other planets long before we’ll get habitats in space. Space is seriously not friendly.
That’s over and above the ton of reasons we have to flee this system.
1) Aliens may come in and kill us.
2) The sun may/will blow up (turning into a Red Sun counts).
3) We may kill ourselves.
4) Something else may kill us (large rock, whatever).
There are serious people right now who think we need to branch off of the planet just to take our own extinction off the table.Report
I agree with all your points, but can’t help but see the bleak absurdity in the last sentence.
We can’t cooperate sufficiently to sustain human life on the one planet that is so insanely suited to human life that it takes a tremendous amount of effort to overcome its natural fecundity and vibrant life.
So therefore, as an insurance policy you know, we will venture out to environments which would demand a thousand times more close cooperation and skill just to sustain the bleakest form of human habitation.
Yeah, that’s a plan.Report
Cooperation won’t be the issue for the Earth if some rock lands on us.
In theory we have robots do the heavy lifting before anyone is even alive.
That’s over and above getting a fresh new start will get rid of a ton of stuff that only exists because it exists.Report
Again, it all comes down to getting out of the gravity well. If we can make that cost reasonable, then ‘bleak’ starts to be less so.
Right now, living in space is like living aboard an old wooden frigate back when those were the pinnacle of Naval Technology. Trust me, it wasn’t pleasant by any stretch of the imagination. If you told a sailor back then that in a couple of hundred years, people would be cruising the ocean on floating resorts for relatively reasonable fares, they’d have a hard time believing you.
Once that cost starts coming down, the necessities that make things bleak can be easily engineered away.Report
That lack of gravity though. Dissolving into a floating bag of meat due to lack of gravity would be awful even in luxurious settings. Can we spin a ship/habitat enough to simulate earth gravity or does that come with its own problems?Report
I feel as if it’s more complicated than that. Certainly engineering problems can be solved, and humans are quite clever, but we are pushing against pretty hard limits of physics perhaps in a way different from ship building.
An analogy: over time engineers got past the sound barrier. Nowadays supersonic flight is easily achievable. By contrast, the light speed barrier — well it’s a different beast. Even getting close to light speed involves exponentially growing energy requirements, which requires fuel, which requires mass, and even antimatter (if that’s even a plausible technology) hits the E=MC^2 barrier.
I don’t want to dismiss our ingenuity. For example, the uncertainty principle puts hard limits on the resolution of telescopes. In turn, we developed interferometers. That’s pretty neat.
The point is, I don’t want to be the modern equivalent of the person who said, “We’ll never break the sound barrier” — however, these are different kinds of problems than those were. Some things will require new physics, and no one can predict what will happen.Report
The speed of light never stops depressing me. The universe is so vast and it is so slow and yet seems immutable. Depression.Report
I go back and forth of this.
Without the speed of light, everything in our Galaxy is next door, which means anything that is older than us is next door. We get to Lovecraft real easy this way.Report
I get it. The vastness insulates us from the horrors but it insulates us from the wonders as well. The vastness is a horror of a sort, an unyielding implacable empty horror.
And if the speed of light is insurmountable, as it certainly appears to be, then so much is utterly beyond our reach.Report
I’m thinking much more pedestrian, like a toilet that doesn’t make you feel like you are getting a vacuum enema.
That new physics kinda stuff is a bit further out than just tossing some habitats between here and the moon / Lagrange points.
Now, if we can manage to crack that fusion nut….Report
Exactly this.
We can build robots, have them go to other planets and build humans with our current Physics and reasonably expected increases in technology.Report
I was commenting more on the idea that Spaceship Earth, the most perfectly designed spaceship for human habitation ever conceived, will become unsuitable for human life due entirely to our own stupidity so therefore Spaceship X will somehow produce a different outcome.
I’m imagining that on Spaceship X there will be some percentage of people who piss into the drinking water because, well, its easier than walking down the hall and you’re not the bossa me.
And other groups of people will tear down the hydroponic towers because damned if those assholes in Pod Bay Ceta are gonna get their hands on it, another group will try to shut down the oxygen generators because the Colander prophesy of the FSM said they were unnatural and yet another group will infect themselves with a virus and go around licking doorknobs because Freedom.Report
Ha! Yeah, OK, that’s a fair concern.Report
This type of world would be amazingly technological and the profoundly ignorant wouldn’t have a spot.Report
You already live in a world of space stations and robot surgeons and genetic engineering, and human behavior hasn’t changed one iota since Juno confronted Jupiter over his dalliance with those nubile nymphs.Report
Everyone is hardly a robot surgeon, and the really stupid stuff underperforms in that kind of person and overperforms in the opposite.
Also part of the whole “robots raise children” is I don’t see how they get brainwashed into believing in [whatever] God. Now maybe some other type of magic thinking rises to take it’s place.Report
Your #2 is objectively true. At some point the Sun will destroy the earth. Our entire Terran biosphere is depending on humanity to save it Human kind are the secular “chosen ones”.Report
IIRC, yes, spinning enough of the ship/habitat to simulate gravity prevents bone & muscle loss, provided you spend enough time there &/or do a prescribed workout regimen while there.
At least, we think so. We haven’t built such a habitat yet to prove that out.
ETA: Misthreaded, sorry North.Report
No big. So if we built a huge ring world in orbit of the sub we could spin it to simulate earth gravity?Report
If we built a ring world that orbits the sun, it would have enough mass (possibly) we would not need to simulate gravity.
But Dyson structures start getting into the whole “new physics” kinda territory.
A simple spindle and wheel station is more than sufficient.Report
Oh yes, I was thinking a ring as in a floating ring the size of earth max. Obviously is we could build a Stellaris style ring world megastructure we’re not worried about gravity anymore.Report
Oh great, you all got me Googling “how much mass would a ring world have”.
Anyway, if this article is accurate, then a ring world probably wouldn’t work:
https://www.popularmechanics.com/space/deep-space/a11183/could-we-build-a-ringworld-17166651/
The basic issues:
* Dynamically unstable
* Mechanical stress far beyond the scale of molecular bonds
* A vast “failure surface” that would doom everyone if things went awry.Report
Like I said, “new physics” territory.Report
Today on Veronica crushes My Sci-fi Fantasy Megastructure Dreams *mascara tears*.Report
If it helps, you have problems with continuous rings, but discontinuous ones…
The math is a bit more forgiving.
The materials science is still out there, but the orbital mechanics are less so.Report
Pfff.. discontinuous ones are just boring ol’ space stations orbiting in formation. Ain’t nobody impressed by that! /sarcReport
Man, just no pleasing some people…Report
We gotta maintain standards when it comes to hypothetical space megastructures darling. Or else the commie aliens win.Report
LMAO!Report
So we give it attitude jets and invent scrith. We have to have a can-do attitude if we’re going to get some rishathra.Report
Captain Kirk was a neophyte compared to the likes of Niven.Report
1) In theory, lots of local spin deals with gravity.
2a) Radiation requires either more mass than we can make economic
2b) or re-engineering humanity so we’re not vulnerable to cancer/radiation.
3) The level of infrastructure to keep things warm/wet/aired over a large area for lots of people over a long period of time is non-trivially large.
4) Worrying about getting hit by very small very fast objects is a thing.
“Spin” suggests one scale of things while some of these others suggest a much larger scale.Report
1) Yes, just need to build something to prove that out.
2) See my comments about radiation hungry fungus and needing to drop the cost of lifting mass*.
3) Not really. Again, make the cost to lift mass reasonable, and you can deal with those issues. And to be honest, air & humidity are a concern (making things air and water tight is always an issue, even our best will probably still leak a noticeable amount of air and water over time), but warmth, not so much. Heat transfer in space is only by radiation, which is slow. Probably have more trouble getting rid of waste heat than you would keeping things warm.
4) Yes, and to date, we don’t have armor that can handle that without hitting bulkhead thicknesses that really make the eyes go up. Best choice is to be in places where there aren’t a lot of small things moving fast. Absent that, it comes back to naval engineering – redundancies and sealable bulkheads. You get hit by a MM, that section either deploys an auto-seal, or it gets closed up until repair crews can respond.
*One thing to keep in mind is that the cost to lift has something of a break over point (no, I don’t know where that is), where we can lift enough mass to establish industrial infrastructure, and then go fetch rocks for raw materials. We aren’t there yet, not even close, AFAIK, but there is a point where lifting raw materials out of the gravity well, even when it’s cheap, begins to be more hassle than it’s worth, once you can process the raw materials in space itself.Report
ThTh5: I’ve been confused on this point, since I figured that infection or a whole virus vaccine would give you antibodies to many parts of the virus, making your immune system robust against variants. This clears up a lot of that. Thanks!Report
It tells me that I was fortunate to get the mRNA vaccine but I wonder if it means that the J&J people are bad off?
Would I benefit from getting the mRNA *AND* the J&J?Report
Being a J&J recipient and reading that it’s less effective against Delta, I was also wondering if getting an mRNA in addition would be smart.Report
Personally, I’d just go for it. Even if it’s not medically necessary, it’ll give you better 5g reception.Report
But it would be annoying if every time I left a store I set off the theft detectors.Report
Apparently the only data available are based on lab studies rather than real-world breakthrough infections, so it’s not clear what can be inferred from this, but…maybe?
https://www.nytimes.com/2021/07/20/health/coronavirus-johnson-vaccine-delta.htmlReport
[ThTh10] And as usual environmentalists blast themselves in the groin with their vendetta against nuclear power. Quelle surprise.Report
I’m all for left-wing activists hurting themselves, but not thrilled with the collateral damage.Report