Everything posted by Genady
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Projected Timeframe for Human-Crewed Deep Space Exploration
In this paper, the authors use the trends of NASA budget and of research activities, and the prior history of the crewed space exploration to predict how far we will go during the next 100 years: [2205.08061] Impact of Economic Constraints on the Projected Timeframe for Human-Crewed Deep Space Exploration (arxiv.org) And here are the results:
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item puzzles
They don't look signifying anything related to math or physics, IMO. Maybe, chemistry? C4BP, for example: C4b-binding protein - Wikipedia
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The Futility of Exoplanet Biosignatures
I think, if we could detect something like DNA or a ribosome, that would be sufficient.
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Do somebody study negative energy particle ?
A 'none-photon' would have mass 0, and thus its energy would be proportional to its frequency, like ordinary photons. For this energy to be negative, the frequency has to be negative. What is negative frequency?
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Do somebody study negative energy particle ?
Exactly. We start with the neg-mass-electron at rest, with kinetic energy 0. It emits a photon and starts moving, in the same reference frame, getting the negative kinetic energy, and the total energy is conserved.
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Do somebody study negative energy particle ?
Energy is conserved if a negative-mass-electron emits a photon. The photon gets energy E and the negative-mass-electron gets kinetic energy -E. This is unlike the ordinary electron which cannot get a negative kinetic energy.
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Do somebody study negative energy particle ?
An 'ordinary' electron at rest would not emit a photon because of the energy conservation.
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Do somebody study negative energy particle ?
Yes, negative kinetic energy and negative momentum.
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Do somebody study negative energy particle ?
Because this would bring them to a lower energy level.
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Do somebody study negative energy particle ?
If they are charged, for example, by emitting photons.
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Do somebody study negative energy particle ?
What would stop the 'regular' particles with negative mass from continuously losing energy while moving to lower and lower energy levels to negative infinity and at the same time infinitely heating the environment?
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The Futility of Exoplanet Biosignatures
I've just stumbled upon this new paper draft, [2205.07921] The Futility of Exoplanet Biosignatures (arxiv.org) and immediately thought of @beecee because of this statement in the abstract: Technical constraints and our limited access to other worlds suggest we are more likely to detect an out-of-equilibrium suite of gasses than a writhing octopus. Yet, anything short of a writhing octopus will raise skepticism among astrobiologists about what has been detected.
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The Physicist and the Philsopher:
I also thing that that "final bit" is incorrect.
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item puzzles
In what sense the other item is "item 1" and this is "item 2"?
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Market Analysis - Is it science?
Perhaps you refer to the dot-com bubble. That was later. When I was involved, the systems operated on client-server architecture with Excel-based clients, relational databases on servers, and SQL "magic" between them. It was fun. The crash of 1998 IIRC was related to Russia, Brasil, Mexico, other financial markets.
- Image from Mars...
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Market Analysis - Is it science?
Here is a true story, from my memory of about 25 years ago. I worked then in Risk Dept of a big international securities company with NY headquarters in WFC, next to the Wall Street. The risk calculations kept showing that a risk of some investment that the management wanted to make, was unacceptably high. But the management wanted it really hard. So we, the financial and the system analysts of the Risk Dept, have spent hours adjusting parameters until the risk came down just below the threshold for the management to justify the deal. The deal went through. A few weeks later, the crash of 1998 happened. The company lost a lot of money. The management was fired. The analysts got big bonuses anyway.
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Do somebody study negative energy particle ?
Dirac did, 90 years ago: Dirac sea - Wikipedia
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Lunar eclipse NOW
Where I live, right now the sky is clear and the Moon is a beautiful dark orange ball! About the max of the total eclipse.
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They report their independent image reconstruction of the M87 from the public data of the EHTC. Their result is different from the image published by the EHTC.
Wait for peer reviews?
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What is the weakest detectable light?
One principle that forbids detection, I think, is the uncertainty principle. The detection time needs to be longer than the wave period (or half, to the order of magnitude). I wonder if there are other fundamental limits.
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What is the weakest detectable light?
In other words, what is the longest possible wavelength which is physically detectable, in principle? Or, the slowest frequency?
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How do oceans affect the Earth's crust?
This is correct. It reminded me of a question from the astronomy class. Sorry, completely unrelated to the OP: During a Solar eclipse, the Moon casts a shadow onto the Earth. Which way is this shadow moving during the eclipse, East to West or West to East?
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First use of 'soil' from the Moon to grow plants.
So, up until about day six the plants used nutrients and organic matter stored in the seeds, and used the soil just to hold to something. After that, the plants needed more from the substrate and then "discovered" that something is missing. I'd guess that botanists know what is missing. I read this news and couldn't understand what was so astonishing, what did they expect, what new knowledge have they obtained...
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How do oceans affect the Earth's crust?
A direct effect of oceans on the underwater landscape is making rocks lighter and thus the underwater mountains taller, canyons deeper, and walls steeper then those above water.