swansont

Collimation is a problem but the real issue is how do you not melt the sails or ship with the intensity you need for a light sail to work with any realistic payload. You need a really big sail. For light F=Power/c; to get 1N of force (1g of acceleration for ~0.1 kg) you need ~150 MW - you get a factor of 2 from perfect reflection, but it’s not going to be perfect, so whatever absorption you have will heat the target. You probably don’t want your laser to have to slice through the atmosphere, but if it’s on a craft in space it’s recoiling with that same photon momentum effect you’re using for the solar sail.

And this issue with those is that to be longer-lived they need to be bigger because longer half-lives mean lower activity for a given number of atoms.

An order of magnitude estimate would be what’s available at night during the new moon (but without the atmospheric losses if you use a measurement on earth) 200 microlux, according to https://en.wikipedia.org/wiki/Orders_of_magnitude_(illuminance) That’s of order 10 microwatts/m^2, so it will be a bit higher in space.

Yes. My objection was to the “simply” as it glosses over the details, which is my main objection in these discussions.

Moderator NoteI think it’s pretty clear that what the OP means by numerology is not the accepted description/definition of numerology. There’s no way to have a conversation in good faith when we don’t have a common language, and this is exacerbated when there is no effort made to correct the misuse of the terminology.

They “shipped” 92 antiprotons, and it wasn’t exactly simple https://www.smithsonianmag.com/smart-news/in-a-first-the-worlds-most-expensive-and-volatile-substance-antimatter-traveled-by-truck-180988431/ It was a trip around the site, too. Nothing was shipped to another lab. The current apparatus – which includes a superconducting magnet, liquid helium cryogenic cooling, power reserves and a vacuum chamber that traps the antiparticles using magnetic and electric fields – weighs 1000 kilograms: much more compact than BASE or any other existing system used to study antimatter. “To reach our first destination – our dedicated precision laboratory at HHU in Germany – would take us at least 8 hours,” says Christian Smorra. “This means we’d have to keep the trap’s superconducting magnet at a temperature below 8.2 K for that long. So, in addition to the liquid helium , we’d need to have a generator to power a cryocooler on the truck. We are currently investigating this possibility.” https://home.cern/base-experiment-cern-succeeds-transporting-antimatter/

Assuming you have a bunch of antimatter, because getting and keeping a bunch of antimatter is simple. Because we don’t notice the alleged aliens sticking around. The analysis doesn’t address this type of scenario. You’re free to start a thread that discusses scenarios that differ from the described one

The analysis was a response to the release of UFO/UAP reports by the US government, so the visits have to be something that would be reported as such. I think arrive, with the ability to maneuver and leave is implied. Something that would look like a regular meteor strike would not qualify, regardless of whether the occupant was sentient.

OK. You still have to get the rock up to whatever speed is necessary, but we know lower speeds are possible. If the rock is too big, the impact at the destination is going to be catastrophic, but that’s also going to depend on the gravity and atmosphere. Plus you’re describing an unguided payload, so this is not responsible for any of the sightings that prompted the analysis.

There’s nothing in the discussion of the analysis that covers this. It’s about how much fuel you need to get to the cruising speed and slow down again, and how the problem is that as you add fuel, you require even more fuel to accelerate it. Any maneuvering of the craft suffers from this problem. Ignoring it doesn’t make it go away. Even for short-range rockets, going relatively slowly, the vast majority of the rocket’s mass is fuel, the container, and the engines The analysis stands regardless of which scenario you apply it to, though a live human going to another system would likely require an even higher speed Doesn’t change the analysis that was given. It means you could re-evaluate based on a lower speed, but the underlying problems still have to be addressed. Photons have a spectacularly small momentum relative to their energy, and 1/r^2 is a big problem. Near earth it’s about 4.5 micronewtons per square meter

How do these spores or seeds reach cruising speed, and slow down when they reach their destination? Surviving the vacuum and cold and radiation in space, and then not burning up in the atmosphere when you hit it at high speed. Robotic craft does not solve the propulsion issues raised in the article. This is the issue of the physics of visiting planets I mentioned. You have to slow down and speed up again to land on a planet or asteroid and then leave, so all you’ve done is amplify the problem that hasn’t been solved. Right. One needs to distinguish between engineering solutions and hard physics limits. The speed of light is a hard limit, as is the requirement for expelling mass for propulsion (unless you use photons, but that carries its own severe limitations) Having to accelerate all of the fuel you take with you is a hard physics limit; you can do analysis without worrying about the specific way you engineer the product.

We have the occasional thread on alleged aliens but nobody ever seems willing to tackle the physics and engineering discussion of how they got here This discusses various methods of propulsion, assuming a cruising speed of 0.1c https://theconversation.com/could-aliens-ever-visit-earth-an-aerospace-scientist-unpacks-the-challenges-of-interstellar-spaceflight-280657 “Consequently, using chemical propulsion on a spacecraft with a cruise velocity of 19,000 miles per second (30,000 km/s) would require more fuel than all the mass in the observable universe” Of course you could go slower but that amplifies some other issues raised, like how equipment breaks down over time. It’d be interesting to see an analysis of what the maximum cruising speed is with chemical rockets, for a reasonable fuel load. It doesn’t investigate other problems you’d encounter that relate to biology, nor does it investigate the problems of visiting planets if you somehow got to a destination.

It does seem a tad laggy for me, too, but by that I mean it took 30 seconds to load instead of 10. And the page is https, so whatever the problem might be, it’s not universal. I’m not an admin, so I don’t know if anything is going on; we’re usually warned when there’s scheduled maintenance/upgrades, and I’ve seen no such announcement.

No, not really. TheVat (not me; you messed up the attribution) said apophenia. Faces don’t have a pattern? I think one big problem here is that you’re imagining definitions for words that aren’t the actual definitions. Makes it hard to communicate properly There are patterns in sewing, too. Having a keyword show up in two descriptions doesn’t mean there’s any kind of equivalence.

And citing them as support is likely confirmation bias https://en.wikipedia.org/wiki/Confirmation_bias

I think there’s disagreement that there’s a “pattern part” of numerology. Numerology doesn’t assign numbers based on some observed pattern or objective metric. So don’t jump past this as if it’s been accepted as given. If you start with the physically impossible, just about any conclusion is possible, but the motivation has no bearing on the validity of the practice. It objectively is not. You don’t get to just make up your own definitions for words

In Pythagorean. Using Chaldean, it’s 9

If the goal is heating, why add the inefficiency of creating steam to make electricity?

One of the more obvious arguments against numerology is there are multiple systems, Chaldean and Pythagorean, which assign the values to letters in a different way. It’s very Industrial Disease (Two men say they’re Jesus; one of them must be wrong) If names were destiny, you’d expect certain numerological trends in e.g. the math standouts in school. And people would be touting this success to sell everyone on their idea.

I think “free” is being used in the thermodynamic sense, rather than the economic sense.

Sci-fi authors and scammers have already monetized the concept. Casimir Energy just cashed in, bilking some venture capitalists out of several million dollars. But there’s no actual product to monetize

District heating using a sand battery as storage for peak demand https://interestingengineering.com/energy/sand-battery-polar-night-energy “The net result: Pornainen fulfilled all of its municipal climate targets with a single installation. Oil use dropped 100 percent, emissions fell 70 percent, and woodchip combustion was cut by 60 percent. According to the Mayor of the Municipality of Pornainen, Antti Kuusela, the municipality now heats all its public buildings, including a new sports arena opening in September 2026, entirely through this district heating network.”

You proceed from a false premise. Numerology is not pattens - that’s not an accurate summary of the practice. So the observation that patterns exist has no relevance. Science observes patterns and discovers a physical reason for them, but numerology does basically the opposite. A Boy Named Sue is a song by Shel Silverstein and made famous by Johnny Cash. It’s fiction. Numerology is less thought-out (AFAICT) than the sociology of how you might be treated because of your name, and how you might react to it. People with the same name don’t necessarily turn out the same.

No. Why would you think that? How does a criticism of a lack of substantiation connect with agreement/disagreement?

You emphasized the wrong bit; that’s an example of what I meant by the lousy track record. The nobody behind the curtain part means that AI is not sentient, and IMO it’s not a good practice to treat it as such.