swansont

! Moderator Note Someone reported the thread; it was closed so the mods could evaluate the report. No, it’s not a problem.

If a photon is re-emitted when the atom drops back to its original state, what is inelastic about the process?

Elastic scattering just means there’s no change in the energy level of the atom or molecule. If the photon is absorbed and re-emitted in a different direction, there is momentum transferred to the atom. It’s the basis of laser cooling. How much “coldness” is contained in an object at 0K?

No concrete evidence means just that - there is no concrete evidence, and you can’t draw the conclusion that it’s aliens. You seem to have admitted that there isn’t any conclusive evidence. Since not everyone is familiar with that, they might arrive at a different explanation. Nothing anthropocentric about the limitations of relativity, and the vast distances of interstellar space.

What does the pea have to contain? All the electronics and the energy source? Really small circuits are certainly possible. Commercially-available ones a little larger than your parameters can be found, and could be made smaller. One limiting factor would be if you have a power requirement

“real” being nonzero but still exceedingly small. How big of a balloon would be required to lift the payload to that height, and would you risk doing that knowing that it might or might not get close to any target of interest, and could be shot down well before that happened? I would imagine the risk is greater from a ground-based bomb in a van, that could be placed in sufficient proximity to a target. A balloon bomb is a threat from a movie writer.

In a word, yes. The same standard, at least, as any scientific endeavor. Possibly higher, since extraordinary claims require extraordinary evidence, but certainly not a lower standard of evidence. Is there a scientific field where “something unusual” is sufficient to draw a definite conclusion? How do you determine the competence? The recent balloon adventures uncovered a story related to this “When the USS New York was sailing towards Iwo Jima in 1945, the crew spotted a silver sphere flying high overhead that seemed to follow the battleship for hours. Concerned that the shiny orb might be a Japanese balloon weapon, the captain ordered it shot down. After the guns failed to score a hit, a navigator realized that they were attacking Venus.” https://www.washingtonpost.com/history/2023/02/03/japanese-balloon-bombs-world-war/ Flawed analogy. You and others keep doing the equivalent of insisting that bigfoot exists, and additionally, is anybody saying not to investigate?

Elastic scattering does this, too. There’s a net outward radiation pressure from any source.

$400k for a missile, but $200k for the training version, so cost without explosive payload somewhere in between. https://en.m.wikipedia.org/wiki/AIM-9_Sidewinder That’s cheap in comparison to US military budgets. The Air Force alone has bought more than 10,000 of them. Raytheon has hundreds-of-million-dollar contracts to supply them. https://www.airforce-technology.com/news/usaf-receives-10000th-aim-9x-sidewinder-missile/ This is peanuts, relatively speaking. And might tick off something on the training requirements for a pilot or two, so these might be in lieu of other missiles that would be fired.

Since a mole of an ideal gas at STP has a volume of 22.4 L, the lift is about 1g per liter under those conditions.

! Moderator Note Rule 2.12 We expect arguments to be made in good faith. Honest discussions, backed up by evidence when necessary. Example of tactics that are not in good faith include misrepresentation, arguments based on distraction, attempts to omit or ignore information, advancing an ideology or agenda at the expense of the science being discussed, general appeals to science being flawed or dogmatic, conspiracies, and trolling. Nebulous claims such as this do not make for a good-faith discussion

And the connection to cold is? This is your proposal. You need to share the details. You can have a high-temperature sample of gas with a large mean free path or a small one. Same for low temperature. Can you clarify this? Radiation can be heat flow, and radiation can cause changes in translational KE. Photons have momentum.

Can you explain what you mean by this? This is something new you’ve introduced, with no foundation.

Can you add coldness to something that has its maximum amount of coldness? Why not?

I recall someone at a science communication conference describing geeks as people who value knowledge more than politeness. That we (I am a geek) don’t mind being corrected because it means we have added to our knowledge. There are some with flipped priorities - they consider being corrected to be rude, with no regard to the veracity of the original claim. Correction just isn’t done, or requires a lot of tact. Scientists and those interested in science discussion, tend to be more in the geek camp than not. There’s no malice assumed when incorrect information is upgraded with better information. For the non-geek, there may also be a matter of projection. One might assume malice if one is prone to being malicious in showing up other people. There are, after all, people who are smart and like nothing more than lording that over other people. I think they tend to belittle others in doing so. A difference between “that’s wrong” and “that’s wrong, you know-nothing imbecile” (aka pushing yourself up by putting others down). I was fortunate in my career in working with lots of smart people who understood there were things they didn’t know, so they didn’t fall into this camp. Most were comfortable in their geekdom.

Also: Why would people who think money is speech come up with convoluted ways to donate more money to the people they support?

PAC donations are separate; they don’t go to the candidate’s campaign. And above I incorrectly said election cycle, but the limits are per election - the limit applies separately to the primary and general elections

Yes, you can contribute directly to a campaign. But that’s limited to $2900 per election cycle for federal office (the amount can be adjusted each election cycle; originally it was $2000 in the 2002 legislation that “reformed” the system) https://www.fec.gov/updates/fec-announces-2021-2022-campaign-cycle-contribution-limits/

It’s perfectly fine to use idealized processes in one’s analysis. And the point is that even if a process is not perfectly isothermal, it is possible to have work done by a change in pressure and volume, meaning such work is not derived from a change in temperature. Are we still in agreement?

It’s called UTC

Yes. It has already been pointed out that one does not generally refer to textbooks of 100 years ago but uses current ones as much as possible, because mainstream science is the science of today, not the science of history. It’s not static. We learn things. Language evolves. A work dated 1904, for example, cannot reflect fully modern notions of energy, since it predates relativity.

Not if it’s an isothermal expansion.

Then let’s look at the Stirling cycle https://en.m.wikipedia.org/wiki/Stirling_cycle Diagram from link 1→2 Isothermal heat addition (expansion). 2→3 Isochoric heat removal (constant volume). 3→4 Isothermal heat removal (compression). 4→1 Isochoric heat addition (constant volume). https://en.m.wikipedia.org/wiki/Stirling_cycle#/media/File%3AStirling_cycle_pV.svg Heat in, heat out

As you’ve noted, we are discussing a heat engine. There can be work without heat flow, but they are not heat engines. Because: no heat flow.

Jupiter is ~5.2 astronomical units from the sun, so it gets (1/5.2)^2 as much energy per unit area, or ~1/27, which is about 3.7%