231–240 of 253 posts
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Yes, both Argentina and Brazil could produce nuclear weapons, given enough time and effort, but neither one of them has ever had them. Neither does either country currently have plans to produce or acquire nuclear weapons, as far as is publicly known. So they are not examples of countries that gave up nuclear weapons. A nuclear submarine is also not what is meant by "nuclear weapon", although it is arguably a weapon…
> Brazil already has many nuclear reactors that are in some sense "totally based on Brazilian technology" and has for decades. I only knew of the three commercial reactors, the third of them under construction for something like four decades and still far from done (and they are also mostly foreign technology AFAIK). So I went looking, and it does seem there are a couple of decades-old research reactors I didn't know…
I went to a state university in the US that had its own research reactor, and I thought their university hospital had another one, but it turns out they don't now if they ever did.
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> It seems to me most scientists in the field are terrified of microplastics Got anything you can point to? I haven't looked for a while but last time I did the evidence of harm appeared quite minimal. I recall that it was quite toxic in aquatic environments that had already been contaminated with (previously mostly harmless) low levels of heavy metals. PTFE is similar in that it too hangs around in the environment f…
Sure, here’s one that’s particularly disturbing and I can’t imagine long term is classified as benign. https://www.npr.org/sections/health-shots/2024/05/22/1252831...
That article cites (https://pmc.ncbi.nlm.nih.gov/articles/PMC9134445).
> Animal studies have shown exposure to microplastics can impact sperm quality and male fertility,
That paper covers numerous aspects. Regarding specifically reproductive harm in mammals, it in turn cites numerous other studies at which point it becomes rather time consuming for me to get up to speed in the nuances of a field that I'm not intimately familiar with.
Having checked at least a few of the relevant citations, it looks like (most of?) the research in animal models involves short term acute rather than long term low level exposure. Not being an expert in this specific area I can't readily assess the quality or applicability of such studies. At least from what I looked through just now I'm not at all convinced that what the current animal studies are showing is (necessarily) directly relevant to low level environmental exposure.
https://pubmed.ncbi.nlm.nih.gov/30176444/
> exposed to 5 μm polystyrene MP at the concentrations of 100 (approximately 1.456 × 106 particles/L) and 1000 μg/L (approximately 1.456 × 107 particles/L) for the toxicological experiment.
https://pubmed.ncbi.nlm.nih.gov/32659591/
> the 0.5 μm, 4 μm, 10 μm polystyrene microplastics (PS-MPs) treatment groups were given 100 μL PS-MPs (10 mg/mL) by oral gavage once a day.
From my perspective there are a couple huge red flags here, and they seem to be present in all the studies I checked just now. I didn't immediately see comparisons of these protocols to the environmental conditions in the world at large (either current or predicted). Neither did I immediately see quantification of the degree and nature of the observed tissue accumulation in comparison to that observed in tissue samples collected in the wild. The latter is of particular concern because these accumulations in the laboratory happened very rapidly (over the course of a few weeks) in the face of acute exposure and impacts were then immediately measured. That doesn't really resemble what's going on in the world at large.
It is of course entirely possible that I missed something when quickly looking over studies that are outside my area of expertise. Apologies if so.
Lest it seem to you that I'm being overly pedantic here consider the difference in outcome for chlorine exposure between long term low level (ie tap water) and short term acute (ie poisoning).
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I'm really curious to know the details here. What is the minimal set of dependencies for the simplest autotroph? Clearly there was an original self-replicating cell and it was successful, so assuming we constructed the necessary proteins, why do you think it would be difficult the second time?
This is the big question about abiogenesis. If it was easy then life in the universe could be very common. If it is exceedingly difficult, we might be alone. What is the smallest set of molecules needed to self-replicate, and how common are the ingredients (& nutrients)? I believe all of this is completely unknown, but I havent looked into the research for years now.
And surely this shouldn't be a difficult question to answer, right? Put an autotroph (the simplest that we know of) in a test tube and give it a ever-stricter diet and observe how far you can go without it dying off.
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Unfortunately, seems the only way to figure this out is by testing. But on the flip, nobody can really trust that it won't accidentally or purposefully escape from labs.
Thus we can conclude military will make them. And they will escape.
Remember, no one has built a regular cell from scratch, much less come close to building a mirror cell.
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That is a completely different thing.
Prove it. Prove that there's not some corner case where a mirrored molecule stops behaving chemically the same towards other mirrored molecules.
Chemistry is about electromagnetism, and electromagnetism has parity symmetry. Also gravity is somewhat important, but gravity also has parity symmetry. And even the strong force has parity symmetry. So for all practical purpuses, chemistry has parity symmetry and when you mirror a bunch of molecules, the mirrored versions will behave exacly as the normal ones.
But ... if you were looking carefuly I didn't mention the weak force, because it breaks the parity symmetry. It's very difficult to prove it https://en.wikipedia.org/wiki/Wu_experiment You have to get a bunch of radioactive cobalts, put them in a strong magnetic field, keep them super cold, and you will get 60% of the decays in one direction and 40% in the other, breaking the 50% and 50% expectation if it didn't break the parity symmetry.
Can this experiment be reproduced in a chemistry molecule?????
I need more questions marks ????????
I think no one has done it and it looks very difficult to try. Can I use my imagination and make will guess?
Let's say you get something like the hemo part of hemoglobin https://en.wikipedia.org/wiki/Heme It has four nice nitrogens that probably can bind to cobalt instead, or perhaps you need a variant. Now make some substitutions to break the symmetry so it it's like a recycle symbol that has a clear direction. Add some bridge under the plane, perhaps connect the small part that is bellow the graphic that I'm not sure why iis useful.
And make the mirrored version too.
Now, if the design was super smart, most of the cobalts in a version will have the north pole pointing to the bridge, and the mirrored version will have the south pole. I'm not sure it's possible, but I can handwave some explanation that say it's possible, but perhaps this idea makes no sense.
Now, did I mention you need radioactive cobalt? When it desintegrates it send an electron that will sometimes colide with the bridge and destroy it, or go in the other direction and keep the molecule without changes.
So after some time the you can see that the time to self destruction is different in the original and the mirrored version.
In conclussion, I think it's possible but no one has done it, no sane person would try it, and if someone get it working then they will get a Nobel price.
It will be very expensive, and completely unuseful, so I completely not expect to see something like this is a living cell.
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This is the big question about abiogenesis. If it was easy then life in the universe could be very common. If it is exceedingly difficult, we might be alone. What is the smallest set of molecules needed to self-replicate, and how common are the ingredients (& nutrients)? I believe all of this is completely unknown, but I havent looked into the research for years now.
I think for the purpose of this topic, we only care about the nutrition (to use your word) question. We can assume humans can intelligently bootstrap past the other abiogenesis problems. And surely this shouldn't be a difficult question to answer, right? Put an autotroph (the simplest that we know of) in a test tube and give it a ever-stricter diet and observe how far you can go without it dying off.
if its fully autotrophic you dont need to add glucose. i think some forms of nocardia can live on m9 minus glucose.
of course anything that can live on m9 has way more genes in it just to biosynthesize the necessary amino acids and nucleic acids. That's why syn1 is a mycobacterium -- fewer genes because it has almost no metabolism. if you look at the biochemical pathways for mycobacterium its laughable how much is greyed out
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Are you suggesting a massive collapse is likely in ~10 years?
Why? You know how averages work?