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You are correct at an extremely high level that the differences in fracture stress and strain between materials (and indeed even between samples of materials) are related to the strength of the atomic bonds within the materials and the crystalline structure and microstructure.

However, that is not an accurate description of what happens to a metal under strain. First, it entirely ignores the possibility (and actual behavior) of elastic strain. Second, even confining ourselves to plastic strain, it's a fundamentally incorrect description of what happens.

It is true that the most common mechanism by which plastic strain occurs is through the movement of dislocations, defects in the crystal structure of the material. But it's not generally true that the strain is taken up by the destruction of dislocations. In fact, it's the exact opposite. When just enough shear stress is applied to begin shifting atoms relative to each other within the crystal structure, existing dislocation patterns within the material begin producing additional dislocations under the applied shear stress. These dislocations entail, by definition, the local shifting of one plane of the crystal relative to another. So when dislocations are generated under shear stress, they accommodate that shear stress by allowing the material to shift in a local way. It is the fact that dislocation generation allows local relief of stress which explains why dislocations are preferentially generated. In order for the crystal to deform along an entire slip plane, all of the atoms must move at once. A dislocation entails the movement of a much smaller number of atoms, on the order of hundreds to thousands.

But the dislocations themselves impose a stress field around them which impedes the movement of other dislocations. So in order for these dislocation sources to produce additional dislocations, they must be subjected to higher stresses. This explains the phenomenon of work hardening, which is present in every metal. If you stress a metal adequately to deform it plastically, additional plastic deformation requires you to exceed that stress in the future, absent any intervening processes which allow the dislocations to heal.

If it were the destruction of dislocations that was responsible for plastic information, metals would actually get softer as they were worked. This is because dislocations disappearing reduces the amount of stress required for those Frank Read sources to generate new ones. And there will always be dislocations present in a crystal at a temperature greater than 0K because it is entropically favored.

If we ignore this effect, and just concentrate on what happens once you have a single crystal without dislocations, under your theory, materials would get far stronger than we can make them at a macro scale today. If there really are no dislocations in a crystal, the amount of stress required to plastically deform the crystal is the amount of stress required to move an entire layer of atoms at once. The amount of stress required to do this is only about an order of magnitude less than the actual stiffness of the material. For a generic steel, this would imply that the fracture stress would be about 20 GPa. But we can't make steels that are stronger than about 1/10 of that, no matter how much we work them.

As stated, no. The object has heat as you ask if it would cool. Total heat would remain the same as energy cannot be lost. It would shed temperature until its thermal energy is in equilibrium with the universe. If it were the only object in the universe, universal temperature would be very close to absolute zero, but just above it by the amount starting thermal energy in the universe, divided by...the universe.

Aren't they all just called Bob?

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All domestic animals are typically considered species but can still reproduce with their wild ancestors, so it's more than one species you would add. Also, dingo are also sometime considered species or subspecies.

No, the concept of an absolute 0 in the first place is purely mathematical/theoretical. It would be impossible to force a particle to have zero thermal, and therefore zero kinetic, energy in a quantum universe. Quantum randomness seems to be a fundamental facet of physics.

The only way to really do this would be to annihilate the universe in its entirety, so that there was no energy or matter at all. But then the concept of temperature would have no meaning.

Lots of people are doing something close when making bent wood rings. This one for example uses crushed turquoise, but grinding it finer and then laying out a gradient likely wouldn't be that tough.

No. Billions of workers don't get you anywhere. You'll need numbers of workers you'll have to look up the names for.

Will "intestinal flushing" events like a prep for colonoscopy impact the gut biome long term? I've heard it's best to eat probiotic rich diet for a few days after drinking that vile concoction and living on the toilet for 18 hours...

If I instead ate a "regular American diet" after a colonoscopy, would my beneficial bacterial composition return slowly, or incompletely?

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Yes, and a compact shape like a cube makes that harder. But the main point is that any conceivable size is still much smaller than galaxy-sized. The death star for example, if it has a level of crew per volume that's comparable to a current ship, would hold several tens of trillions in personnel. And it's tiny, like a quarter the diameter of Ceres. But it could be built without requiring magic materials. Moving it would be a different issue.

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Well, that's a questions I can answer! I have been working for more than ten years in the field of ML and omics data.

First, definitions (aka nit picking):

• Machine Learning is a part of Artificial Intelligence.
• Genomics means to study the DNA and all genes (the genome) of an organism. There are other "omics" like Transcriptomics and Metabolomics.

One straightforward example is the detection of changes in the DNA (mutations) that cause a certain disease or lead to a phenotype of interest. Possible research questions are: Which mutations allow modern humans to digest milk as adults? Or: What is the ideal combination of gene variations to choose to breed a drought resistant corn variety?

A popluar approach to finde those mutations is called Genome-wide association study (GWAS). Basically, you collect a big table of every mutation you can detect in thousands of individuals. Additionally, you record the disease state (digest milk yes/no) or observed phenotype (corn yield under moderate drought):

One option is to run a statistical test for separately for each mutation and see if there is any significant relation to the phenotype. This has been done in the past with success. However, this approach misses cases where two or more mutations are necessary to produce a phenotype. Say, humans have two copies of a gene and a for an observable disease to occur both need to be damaged by a mutation (e.g. introduction of a stop codon). To catch such cases, we can use (simple) Machine Learning models. Again, there are many options. One is a constrained linear model called Ridge regression. We encode the mutations using numbers and train a model to predict the phenotype based on those numbers. During the training, the model finds patterns of mutations that are best suited to predict the phenotype as accurately as possible. There are many caveats I skip over here. Afterwards, we can inspect the model to extract these patterns and thereby find the responsible mutations (and the genes they affect). However, these may or may not be the causal mutations. They are "just" predictive - or correlating with the phenotype if you like. Nevertheless, these genes could be a starting point to develop a new drug or serve as biomarkers for a diagnostic test.

That's very briefly ML in genomics.

Throwing in an example paper for good measure: Genome-wide association study and genomic selection for yield and related traits in soybean - this is basically the corn example from above.

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In linear algebra and other types of mathematics, the notion of perpendicular is generalized to "orthogonal" in different coordinate systems, with the idea that a certain type of "product" between two vectors (i.e. the "dot product" in our familiar cartesian coordinates, and more generally the "inner product") equals 0.

At a small enough scale we can treat the earth's surface as a flat plane and still get reasonable results, though on bigger scales we have to use a roughly spherical geometry. On a sphere you can still have two orthogonal axes for your coordinate system, just the path you travel affects what direction you end up facing differently from a plane. Triangles add up their angles differently from a flat plane, etc., but that only matters if you are traveling very far.

So there is one broader mathematical definition of perpendicular of which our coordinates on Earth are a special case. But why have we chosen perpendicular axes? Historically, perhaps because it's a simple and intuitive way of describing the geometry we can see and interact with. Sort of an emergent property of human thinking, when people in antiquity were working mathematics as it related to everyday experience. Humans seem to like symmetry and simplicity, so a four-fold symmetry of right angles is a "nice" coordinate system to us.

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I’ve seen a (presumably not faked, but 🤷‍♂️) natural gemstone posted somewhere on here that was a different type on either side of the stone. I forget what they actually were (I think they were purple and orange though, so maybe amethyst and…something orange?), but is there a natural process for producing this sort of thing? I’m assuming it would be very dependent on the exact stones, and wouldn’t just work with any combo, if it’s possible at all. Maybe it was the same type of crystal with different impurities?

I took some geology classes in college, but it was back when I still believed in the young earth indoctrination of my childhood. After leaving all that about a decade ago, I began studying on my own and was really frustrated with my younger self. My favorite thing I recently found was that my state, Florida, was on two separate tectonic plates.

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