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1. ## joigus

Senior Members

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2. ## iNow

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21644

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4. ## studiot

Senior Members

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## Popular Content

Showing content with the highest reputation since 06/10/20 in Posts

1. 5 points

## Does Zoro produce enough aerodynamic lift here according to the Bernouilli's principle?

At which point, I have to post this: https://what-if.xkcd.com/1/ Spoiler: it doesn't end well
2. 4 points

## Climate Change

My little bother just ate all the Scrabble tiles and his poop made more sense than you do.
3. 3 points

## Gravity

The 'bowling ball on a rubber sheet' is a two dimensional reduction of a 4 dimensional configuration. It has multiple problems, one of which is that you can observe it from an embedding third dimension. Space-time has no embedding dimension; both the bowling ball and you, the observer, would need to be intrinsic to the rubber sheet ( i.e. also two dimensional ). A three dimensional representation would already get rid of some problems, but not all. Picture a three dimensional grid, where x, y, and z axis divide up the space into cubic elements. A mass placed in this space would curve the x, y, and z lines such that the elements are moreskewed, and smaller, as you get closer to the mass. That is 'space' curvature, and one aspect of gravity, but already much harder to visualize than the two dimensional example of the bowling ball/rubber sheet. Actual gravity is four dimensional 'curvature' of space-time, and I can't help you visualize that as it is impossible. Some problems are just not suited to visualization, but understanding even just the basics of the math goes a long way to clarifying things.
4. 3 points

## Experiment verification of General relativity

Just to add to what has already been said by other contributors here: 1. First and foremost, the notion of "gravitational potential" can only be defined in spacetimes that are stationary (more precisely: those which admit a time-like Killing vector field) and asymptotically flat. It cannot be generalised to more general spacetimes, which makes it useless so far as a general model for gravity is concerned 2. Gravitational potential itself is not an observable, only differences in potential can be observed and measured. This is because the potential has a gauge freedom, in that one can freely choose where the zero point is, without affecting the physics. The same is not true for the speed of light, hence the relation above is trivially and obviously wrong, since it equates two quantities that cannot physically and numerically be equal, on fundamental grounds. 3. A varying speed of light would constitute a violation of Lorentz invariance. This symmetry has been experimentally and extensively tested with modern equipment to extremely high precision, both here on Earth and in the vacuum of space - needless to say, no such violations have ever been found. Given the degree of precision of these tests, any variability in the speed of light can effectively be ruled out far beyond the usual 5 sigma threshold. 4. A variable speed of light would also break CPT symmetry, which underlies the Standard Model of Particle Physics. Since we continue to successfully use and test this model in particle accelerators on pretty much a daily basis, any variability in c can also effectively be ruled out on that ground. 5. Neither classical Maxwellian electrodynamics nor quantum electrodynamics allow for varying values of permittivity and permeability (in the same medium of course). Hence the notion of a varying speed of light is actually in direct contradiction to what we know about electrodynamics. 6. As has been pointed out on another recent thread, a scalar field theory such as this one is fundamentally incapable of capturing all required degrees of freedom of gravity; there is more to gravity than just time dilation! I could probably go on, but these are the points that immediately come to mind without thinking about the issue too much. I'll leave it at this.
5. 3 points

## There's a black hole lurking within 1,000 light years of Earth – and you can see stars circling it with the naked eye

Disclaimer: Black hole not visible, southern hemisphere required. https://www.theregister.com/2020/05/06/nearest_black_hole_earth/
6. 3 points

## Discussing racism/bigotry (split from The Killing of George Floyd: The Last Straw?)

You mean calling him a "racist"? That is no more "name calling" than referring to someone a "physicist" or a "plumber". Name calling implies an insult. "Racist" is a title he earned all by himself. I don't see what is to be gained by dancing around words to spare people's feelings. This place is not a quilting circle. So there is the "status quo" and there is "your way". Some people feel there are other means to change the status quo, and they don't involve allowing others a platform to share hatred and bigotry. I allow no room in my heart for showing understanding for racism. Hatred of others based on the color of their skin is never acceptable to me. I will not stand by while others spew hate without calling them out. There is a reason people lose sponsors, advertisers, and even jobs after making racist comments. It is not acceptable. I don't see why we should be an exception.
7. 3 points

## hijack from The Killing of George Floyd: The Last Straw?

! Moderator Note No, you're racist because you espouse racist beliefs, the expression of which on this forum (besides being wrong) is also against the rules. Consider yourself banned.
8. 3 points

## Confused About the Earth's Early Atmosphere...

Just to add info. The oxygen in photosynthesis comes from the breaking up of water molecules. The possibility that it came from CO2 has been ruled out experimentally by using isotopic tracers. https://www.amazon.com/Life-Science-William-K-Purves/dp/0716798565 (chapter 8: Identifying Photosynthetic Reactants and Products) Water was very abundant in the atmosphere after the late heavy bombardment.
9. 2 points

## United States Will Withdraw From The World Health Organization

He launched yet another weapon of mass distraction
10. 2 points

## Teaching Science and Asperger's Syndrome

With the exceptions of occasional crackpots, the selfish, the unkind, and the uncouth; and on rare occasions, the sheer lunatics that come and go, most of the members of this community are giving me an enormously valuable environment to exchange ideas. Teaching has been a great pleasure for me for many years. Now, for the first time, I'm tutoring a boy that suffers from Asperger's syndrome. After a month now, I must say that it's been one of the most gratifying teaching experiences I've had so far. Things are going pretty well, good results keep coming, and everyone involved seems to be happy. We've started with maths. Every time he shouts “now I understand it!” is priceless. But he's emotionally vulnerable, and also gets quite anxious when he misunderstands something and gets embroiled in the wrong calculation. The verbal feedback is somewhat wanting, because he stumbles over words and speaks too quickly for me. So sometimes it takes me a while to realise what he really means. Any experience that any of you may have to share with me, any tips and directions, will be greatly appreciated. Especially heads-up when it comes to physics, which I'm kind of dreading.
11. 2 points

## What is the correct definition of zero error?

I agree that the OP definition is not quite right, but both your A and B examples have two errors. Yes a zero error is a systematic error but it is not due to a wrongly marked or non uniform graduation and yes it can result in an increased or decreased actual measurement. A simple example of a zero error would be dirt on the pan of an otherwise accurate weighing scale.
12. 2 points

## Scientist saving the world from destruction.

Well, I'll be damned. One wave of the hand, and 5+ billion of us, who just happened to be born into non-Christian cultures, sentenced to burn in hell for all eternity. Makes me wonder just which of those two guys to blame, really.
13. 2 points

## Responding to 5G Conspiracy Fears

Aren't you all glad that you found science as an interest/vocation? We could all easily be victims to this kind of BS if we didn't know the science basics.
14. 2 points

## How can we apply accoustics to tell the difference in power between these two characters?

Sound we regularly experience carries very little energy. 80 dB is ~ 1 milliwatt, so assuming 100% efficiency: “to heat up a quarter liter of coffee 50 C it would take: 1 year, 7 months, 26 days, 20 hours, 26 minutes and 40 seconds” https://www.physicscentral.com/explore/poster-coffee.cfm 130 dB is just 10 watts, though it is logarithmic https://en.wikipedia.org/wiki/Sound_power
15. 2 points

## need help understanding data and information abstractly

My very short answer: A value of a random variable. Let's say you receive a symbol "1". If this is the only possible symbol the fact that you received it does not give you information. But if this symbol is one of two possible, "0" and "1", then the reception of symbol "1" may contain information. So having more that one symbol is a requirement, but not sufficient. Lets say you receive the pattern "111111...". The probability of the symbol "1" is 1. Again there is no information. But if random sequences are allowed, for example "00", "01", "10", "11" then we may use these sequences to represent information. So conceptually information can be seen as a value form of a random variable. The above is an attempt at an extremely short introduction to information theory, which is tied to discrete probability theory. Most important early contributor was Claude E. Shannon and his paper “A Mathematical Theory of Communication”, dealing quantitatively with the concept of “information”. Shannons concepts and the mathematics he used to describe information and to measure information content is a remarkable contribution. I believe it's tricky to find any areas of IT where his work does not contribute. Wikipedia* has links to some concepts related to your question. Feel free to ask additional questions. *) https://en.wikipedia.org/wiki/A_Mathematical_Theory_of_Communication For an early predecessor of Shannon, working on sinus signals and frequencies, see Hartley: https://en.wikipedia.org/wiki/Ralph_Hartley
16. 2 points

## Does Gödel's Incompleteness Theorems means 2+2=5?

No. They are purely about the "completeness" of formal systems. In other words, can a formal system (e.g. mathematics) prove that anything that can be written down using that formal system is either true of false. And the answer to that is no. You can write something using mathematics that you cannot use the same mathematics to prove or disprove. You can extend your formal system to make it more complete and allow you to prove that statement. But then there will be other statements that this extended system cannot prove. And so ad infinitum. Physics uses mathematics but it is not limited by that mathematics in the same way. (And some mathematicians complain that physicists are a bit "ad hoc" and don't really stick to absolutely formal derivations.)
17. 2 points

## Wash away of \$1Trillion worth of marshes

That is out of my knowledge. The only thing I can say is that trying to change the elements (river, sea, land) in a specific way most of the times drive to unexpected results. I have the experience where a hotel constructed a small dock in the sea for his single inflated boat sportcraft had the result to erase completely its sandy beach.
18. 2 points

## Does Zoro produce enough aerodynamic lift here according to the Bernouilli's principle?

Since this is the lounge I'll do some less rigorous analysis showing why science is of no use. Observations in the movie clip. 1: Zoro does not seem to follow the trajectory of a massive object; heigh above ground seems maintained. 2: Zoro does not seem affected by air resistance; speed is not reduced during the flight 3: There is atmosphere on the world where the fight takes place. 1: means that (a) Zoro is either massless* and hence unaffected by gravity or (b) neutrally buoyant in the atmosphere, like as a hot air balloon. 2&3: means Zoro could be (c) extremely dense, having extreme momentum. But (c) can't be compatible with 1, massive object fall down. And (b) is not compatible with 2, balloons stop quickly when thrown in air. (a) is pointless, a massless Zoro, swords included, would have zero effect on a stone golem; there is no kinetic energy or momentum that can affect the golem. That means Zoro travels through air by magic because the described airstrip is physically impossible. I do not know how magic affects drag and Bernouilli's principle, so again: Side note: That fact the manga story is failing to describe physically probable action does not mean I can't see it as entertaining. I enjoy entertaining stories, if the canon of the universe where the events take place allow magic, faster than light travel etc I don't care how impossible that might be according to mainstream science. I just chose to not mix my interest in science and engineering into the events of fiction and fantasy in the story. *) I know that would mean a photon speed of c in vacuum and massless bodies of macroscopic size does not exist AFAIK; creating one would require magic. But this is the lounge after all, and we will get to the point anyway.
19. 2 points

## Black holes and evaporation

Just to add to that, it's not like in SR where each observer also has a different notion of simultaneity, but each of those is physically meaningful. Eg. in flat spacetime, any two events that can be considered simultaneous by someone will have intersecting future light cones, where different future observers can agree or disagree on whether the events were simultaneous. In GR you must make a choice of how to define the surfaces of a foliation, that's not just based on a physically meaningful connection between its events. You'd choose it to make a useful tool, not a 'real' representation of simultaneity throughout the universe for a given observer.
20. 2 points

## Do they belong in this thread or psychology?

If you have scientific evidence for a non-mainstream topic, and you think you can defend it reasonably, put it in Speculations. If it pertains to a field of personality studies you can defend using science, post in Psychiatry/Psychology. If it's something you feel might pertain to a specific philosophy or ethical approach, post in Philosophy. If it's just New Age mysticism that works because you say so and wave your hands a LOT, please don't post anything at all.
21. 2 points

## Questioning the Basis of Christianity

There are things the Bible doesn't say and almost everybody believes it does. There was no apple. It could have been a quince, or maybe a fig, as there were no apples back then in the Middle East. The Bible doesn't say it was an apple, actually. The Bible doesn't say Jonah was eaten by a whale either. The Bible doesn't say there was an angel at the Garden of Eden, but a cherub, which was a mythical animal represented very frequently in the gardens of palaces throughout the Middle East. The Hebrew Bible doesn't say that Mary was a virgin, but a "young woman." ------------------------------------------------ There are things the Bible says and few people know it does. The Bible talks about a pantheon of gods that are subservient to Yahweh. And names God both as Yahweh and El. Is it the same god? I'm not sure. Asherah, the wife of Yahweh, is also mentioned, but the interpretation was presumably changed, as it's mentioned as a synonym for "a stick" in very obscure passages, when she is known to have been a goddess, as archaeology has shown. The stick was one of the symbols of the goddess. Back to Adam and Eve: There's at least one thing the Bible says twice in different (incompatible) ways: Ezechiel 28. Two prophecies, one of them against the king of Tyre. There you can see that the king of Tyre is expelled from the Garden of Eden, on account of his sins. The cherub also appears. Very similar legend; two different narrative uses. Who was expelled from the Garden of Eden, Adam and Eve or the king of Tyre? I'm not so sure. The authors of the Bible seem not to be either. Some scholars believe the Oracles against the king in Ezechiel 28 predate the Adam and Eve story in Genesis. ------------------------------------------------ There are things the Bible says that are taken from somewhere else: The Bible takes the story of Noah from The Epic of Gilgamesh, Utnapishtim , and adapts it to its own narrative needs. ------------------------------------------------ There are blatantly obvious things the Bible is silent about: Omri, big king of Samaria, was a very relevant character of the Assyrian domination period, but the Bible only mentions him in passing, as a baddie. The Bible also plays down the role of many other kings, like Manasseh, although he made Israel into an important olive oil factory and brought a period of peace, contrary to what Hezekiah, his father, did. ------------------------------------------------ And lastly, there are many things the Bible says that cannot be true. Josuah didn't conquer Jericho, as Kathleen Kenyon has proved. Jericho was uninhabited at the time. Plus the Egyptians were in control of Canaan and had the country strongly policed from Beit She'an. I don't believe God gave the law of gravity a suspension for some hours for the benefit of his people to the detriment of the Canaanites either. Plus the Canaanites and the Israelites were the same people: No difference in material culture or belief system, as Israel Finkelstein has shown. Abraham could not have possibly used camels. Camels were domesticated about 1000 years later.
22. 2 points

## Does Gödel's Incompleteness Theorems means 2+2=5?

Hello Francis and welcome. The short answer is no Godel is not about statements we can prove, like yours, but statements we will miss out because we cannot derive them from our axioms. There is a really good introductory book by Raymond Smullyan about this called Forever Undecided Which is fun to read. I think a pdf may be available. Meanwhile here, what do you know about axiomatic structures in Mathematics?
23. 2 points

## "Belief", "Beliefs," and "Issues of Belief"

One of the best little pieces of comic theatre of all time was based on this. Here is wikipedia, you may be able to find a ytube of it. https://en.wikipedia.org/wiki/Class_sketch Yes indeed it is quite long, so I do not find it suprising there are some contentious points. The author is rather dismissive of the use of auxiliary verbs in general and the verb to be in particular. He claims that the verb to be is unneccessary and has almost withered away. Not so. Consider the travels of Marco Polo to China, a jourrney that took several years. Had he been English, Marco might have said, "I'm going to go to China next week." As he left Italy he might have said "I'm going to China". Two years later he was still "going to China", he had not by then arrived. One thing he would not have said would be "I go to China". The action was "imperfect" as it occupied an extended length of time and was still in progress during other events that might be spoken about. Imperfect here means that it is not complete at the time of utterance. A perfect action is complete from start to finish. An imperfect one may never be completed for some reason. Two other gripes with the article. Firstly no mention is made of the difference between spoken and written language when comparing English to other languages. It is my belief that this difference is one of the key factors as most languages are largely phonetic, English being the glaring exception. So it is emminently possible to learn and know many words and the associated grammar in English but not to be able to say or recognise them when spoken. Even English speakers sometimes have this trouble. Take the letter a as in car or cat. The big difference in the pronunciation of the 'a' leads to two difference pronunciations of the word castle, which confuses many. Secondly the thesis that it was the influence of the Vikings who did away with the manyfold word endings. One wonders why they did also do this with old French. Or why the endings were still there in middle English a couple of centuries after the end of the Viking era.
24. 2 points

## Experiment verification of General relativity

We can already invalidate Yanchilans theory as we have already tested different gravitational potentials for time dilation at different elevations. With precision atomic clocks. Even testing it a distance of one foot. The results agree with GRT. https://www.nist.gov/news-events/news/2010/09/nist-clock-experiment-demonstrates-your-head-older-your-feet This isn't the only experiment done at different elevations. I assisted at a University that also conducted similar experiments as part of the course curriculum. Though we used the coastal mountains of BC coast. It was pointless publishing the results. Nothing newsworthy or unexpected.
25. 2 points

## "Belief", "Beliefs," and "Issues of Belief"

When people say "Well, the dictionary says..." they obviously don't realize that a modern dictionary is a contemporary record of usage and not an authority. The people at large determine the usage in any given period.
26. 2 points

## Black holes and evaporation

That is a really good question, because I still don't know what your position actually is. You seem to be saying that the concept of an evaporating Schwarzschild black hole is self-contradictory - which is trivially true, because Schwarzschild black holes are of course stationary by definition. But evaporating black holes aren't of the Schwarzschild kind, so where exactly is the issue? Then so you also seem to be saying that even ordinary Schwarzschild black holes are self-contradictory, because somehow event horizons can't exist? But I don't understand why you think this, because the reasons you give don't make any sense.
27. 2 points

## vedas and twist

I think it makes no sense to say that the vedas were twisted or not. They have grown organically. There are so many reasons for a text to change, especially when it originally was an oral tradition. Without having the 'original' how would you see that the texts changed? There are methods to find out which of the present versions we have are probably the oldest, but of course we can have no idea what the first written down version of the vedas were. And then there are many reasons why texts change over time, just to name a few: errors when copying the texts corrections of (language) errors authors putting in their ideas into the texts, in good or ill faith I only know a little about the history of Christian texts, which are of course not so old as the vedas, and also here already the problem exists that we do not know exactly what the original texts were. But we know copyists made errors, corrected errors, put in sentences or even complete stories, often because these copyists had a theological agenda to promote their version of Christianity. From some texts we know that there must have been more original texts, but they did not survive. With the vedas this will be worse, because they were orally passed to others for a much longer time. In Christianity, especially the new testament, there are at most only about 100 years between the oral tradition and the first written down versions we have (often less: the gospels were written till about 100 years, the earliest one probably only 30 years, after Jesus' death). With the vedas it is several millennia before they were written down.
28. 2 points

## Black holes and evaporation

This is what I got from your posts: 1) A black hole and all the events in its interior can be described in the coordinates of an observer at infinity. 2) A Penrose diagram of an evaporating black hole shows that the formation and disappearance of a black hole have the same time coordinate. 3) If an event A has a coordinate time that is less than the coordinate time of an event B, then A happened before B (maybe even in B's past?). Problems with this: (1) The interior events do not have meaningful time coordinates for this observer. (2) If that's what the diagram really shows, then the coordinates used in that diagram can't be the same as for the observer in (1). (3) You're comparing coordinate times of events that have no causal connections, and their ordering is irrelevant, but you see "logic problems" by treating it as something physical.
29. 2 points

## Black holes and evaporation

Really ? Cosmic rays enter the atmosphere billions of times, yet not a single micro BH has ever been detected. Maybe you can produce a citation of a detected micro BH. I can certainly post numerous citations of cosmic ray detections.
30. 2 points

## vedas and twist

Stu the cockatoo is new at the zoo...
31. 2 points

## The Killing of George Floyd: The Last Straw?

The issue that I see with this thread is that I'm proposing actual implementable changes. To the Police Unions and Hiring/training practices, for example. Then we start to work on the DAs who bring up unfair charges on minorities. Saying the problem is systemic ( your meaning CY ) means the whole justice system ( and more ) needs to change, from cops, all the way to the Supreme Court. And we both know that's not going to happen; so nothing will change. The higher up you go in the justice system, the more political it is. And with your polarized two party system, who would even propose such a change, and hope to get re-elected ? Myself, I don't see the point of self-flagellation, and saying "It's all whitey's or the system's fault, and not trying to do something about it. People are dying needlessly, and all I'm hearing is blaming, but no solutions.
32. 2 points

## The Killing of George Floyd: The Last Straw?

Where did this red herring come from? We’re not talking about all criminal activity, we’re talking about police, who are supposed to protect and serve the public, and who should be held to a higher standard. We’re also talking about violent behavior. That’s not an instance of excessive force. I was short of straw before but now I have a lifetime supply. Sure. But you had only proposed screening for white supremacy Yes. If they had not tolerated such behavior, you might say...
33. 2 points

## Space Time

I suspect it relates to the alleged instances of people time travelling without the benefit of physical mechanism. The example that comes to mind is of the two visitors to Versailles early in the 20th century who seemed to be transported back to an earlier period where the people they saw and the layout of the gardens matched (allegedly) the late 18th century. Wikipedia article. There is also a silent movie era newsreel (?) in which a member of the crowd appears to be using a mobile phone. All of the instances have simpler, more convincing, mundane explanations, but its a useful plot device for stories.
34. 2 points

## Is Nature playing fair with Krauss Object?

They are NOT the exact same things. You are confusing the word "special" with the word "preferred". We don't laugh at the the idea of the Earth being in a special place, we laugh at the idea that the Earth might be in a preferred place. When you were but a wee child and your mother said you were "her special boy", she simply meant you held some significance for her. You were 'neat', or 'cool'. She wasn't implying that the universe was centered on you. Similarly, we live in a special time and place. We witnessed the first time humans detected gravity waves and the invention of the autostereogram. If we weren't at this location (on Earth) at this time, we could not have seen that with our own eyes. Unfortunately we did not exist at that special time when the four fundamental forces were combined, but we are lucky to live at the special time when all these superclusters can be detected. And that is really neat.
35. 2 points

## Sleep and time

Dreaming is a process of organizing thoughts in new ways. Memories get consolidated, and it happens while our normal connection between our brain and our body is “severed” ... much like our normal connection to time while we dream can be discarded. I don’t believe we see the future in our dreams. I believe instead that our conscious mind struggles to make sense of these more unconscious processes and so applies narratives which DO make sense to us. These narratives are not tied to specific events and so are not anchored to chronology in the normal way our daily experiences are. These narratives and insights and feelings are essentially intuitions that we selectively remember at a later time (“hey... this pattern I’m seeing right now IRL is incredibly similar to that pattern I experienced all those weeks ago in my dream!”). We then call this feeling deja vu or mistakenly describe it as precognition. Its a pattern, and humans are incredibly good at finding patterns even where none exist. Note: This is my own conjecture, not necessarily a representation of the most current research. Apologies for inserting a speculation into a non-speculative thread. Could be both. Hit the quote button.
36. 2 points

## Trigonometry (Law of Cosines)

Yes it helped and I got my answer.
37. 2 points

## Discussing racism/bigotry (split from The Killing of George Floyd: The Last Straw?)

There are two somewhat different issues here: one is discussing racism in general, and another is discussing it on this site. As for the latter, as iNow and Phi (and possibly others) have pointed out, we want arguments to be in good faith. Disagreement must maintain a certain amount of civility. So if someone shows up dropping N-bombs, or disparaging religions, they will be shown the door. We are not obligated to make people suffer written abuse in an effort to change a bigot's mind. If that's the price of participation, for us it's too high.
38. 2 points

## Discussing racism/bigotry (split from The Killing of George Floyd: The Last Straw?)

Racism isn't about labels, it's about hate. Hate is an issue of emotion not intellect. As emotion, the afflicted may only be solved or remedied by therapy rather than by reasoned discussion as we may find in open forums like this. In this forum, we can intellectualize the causes and cures for hate but we can no more treat that condition via our online debates with racist than we can remotely remove a tumor. There's a reason why this science forum discourages visitors seeking medical advice. Similarly, there are reasons why hate filled sufferers are equally discouraged in this forum. They need help we can't render here.
39. 2 points

## Banned/Suspended Users

essereio has been permanently banned for repeated violations of rule 2.1.
40. 2 points

## Microservices or Client-server Model

I assume you aren't making the final decision so don't take that responsibility. You should create a PowerPoint presentation referencing the various options that are available and present that to the other members of your team so an informed decision can be made. If you are uncomfortable doing so yourself I'm sure you can recruit a consultant on a temporary basis to do so.
41. 2 points

## Microservices or Client-server Model

With the limited information available my answer will be very general. I would be cautious if someone provides detailed answers based on limited information. 10s of thousands can be a tiny or huge depending on the amount of data, how the traffic is clustered, response time requirements, processing required to create an answer, what standard services that are already available as services, API, micro services etc.
42. 2 points

## Does outer space have drag?

Not sure what you mean by time being reactive. And I don't understand why that would mean it travels. I don't even understand what it would mean for time to "travel". 🤷‍♂️ No. Photons are massless. It has nothing to do with terminal velocity. Light always travels at the same speed. No. Photons do not have mass. And even if they did, it would not imply that space has drag. Nothing with mass can travel at the speed of light. No. Photons always travel at the speed of light. Which is why it takes them 8 minutes to get to Earth from the Sun. No.
43. 2 points

## Removing Civil War Monuments

People really need to ask themselves why communities erected statues of slave holders and not of abolitionists. h/t AOC
44. 2 points

## Does it make sense to say that something is almost infinite? If yes, then why?

In mathematics the problem is the 'almost'. So no it makes no sense. In Physical Science then yes phrase may have value, for instance an 'almost infinite thermal reservoir' in Thermodynamics or 'almost infinite dilution' in Chemistry. In each physical case the phrase measn that the quantity concerned is so large compared to the change considered that the quantity is constant or unaffected by the change. This is just making use of one mathematical property of infinity that infinity plus or minus x is still infinity.
45. 2 points

## Teaching Science and Asperger's Syndrome

Well, I'm not too sure what 'mild' in this context really means, but I'm certainly high functioning, and require no intervention or assistance to live a normal life. This is mostly because I have learned since childhood to mask my autistic traits to such a degree that most people won't be able to tell at first glance that I'm neurodivergent. In my case, I find it easy to express myself in written form; however, if we were in the same room, and I was asked to explain some GR concept verbally, then that would be much harder for me, especially if I didn't have time to prepare beforehand. And the subtleties and complexities of casual social situations will forever remain a mystery to me, even though I can outwardly play certain roles if necessary. This is a difficult subject, because the spectrum is so wide. Personally, I never thought of myself as having a disorder of any kind - I think of myself as neurodivergent. As being differently abled, rather than disabled. I consider it a gift, and if I was being reincarnated, and somehow given the choice, I would without a shadow of a doubt choose to be on the spectrum again, since for me the positives greatly outweigh the (nonetheless very real) challenges. I do recognise though that many others on the spectrum would disagree, since their autistic traits are more challenging for them, and they suffer from various comorbidities, such as ADHD and SPDs.
46. 2 points

## Think of a body which is at rest but not in equilibrium. Give explanation as well as figure/diagram.

At maximum height $\boldsymbol{v}=0$ but $\boldsymbol{a}\neq0$ Is that what's confusing you?
47. 2 points

## Teaching Science and Asperger's Syndrome

Nice post +1, I'll just add, in my work with differently abled humans, a good way to think of the differences; if a bus runs into a group of people, one extreme is, OMG how many people were hurt, while the other is, what colour is the bus. The OMG's will never really understand the what colour's, and vice versa; all we can really hope is, we understand that there's a difference in all of us...
48. 2 points

## Teaching Science and Asperger's Syndrome

If you get really good at setting expectations, you'll find it helps with everybody on the spectrum (which I suspect is broader than we think and may include a lot more of us). It may simply work on everyone. It's the equivalent of someone like Elizabeth Warren always having a plan. It allows people to make their own plans based on yours, and it's very comforting and satisfying, and makes folks feel great about following your lead. I recommend watching Hannah Gadsby's new Netflix comedy special Douglas if you can. She's been diagnosed with high-functioning autism, and she has this brilliant convention where she tells you EXACTLY how her standup show is going to unfold before she starts, in order to set your expectations as an audience member (I hope she continues this format in future shows). Then she does the show, and it's amazing how much funnier it is because you know what's coming. She also touches on several spectrum-related behaviors you should be aware of (beware the Puffer Fish). Thank you for taking the extra time, and also for recognizing that the way these beautiful minds work is just different, not abnormal. Your student appreciates it more than they're probably telling you.
49. 2 points

## Fermi paradox solutions

You're both welcome. A couple of things more. First, I just wanted to add that Fermi was no idiot, of course. But the assumptions he made date back to 1950. We know much more about planets now. Something we know now, for example, is that the Earth-Moon system is far from typical. The Moon is an unusually large satellite and has a rather bigger than normal stabilizing effect on the Earth's tilt. To the point that astronomers are starting to look upon the Earth-Moon system as a binary planetary system, rather than a standard planet and its small satellite or group of satellites. The huge tidal effect that the Moon has on the Earth is believed to have played a major part in the origin of life at least during the first billion years, stirring the chemicals dissolved in water and thus triggering volume reactions (much quicker and efficient) rather than surface effects. https://www.space.com/12464-earth-moon-unique-solar-system-universe.html Another factor is the presence of outer giants like Jupiter and Saturn, for billions of years playing the role of shuttles for asteroids from the Kuiper belt, etc. Water and amino acids in the asteroids are also thought to have been very important. In case any of these factors were found to be essential to the appearance of life, it could be a basis to estimate the number of solar systems in the Milky Way that satisfy similar conditions. Would other different sets of conditions be just as good, or maybe even better? I don't know. I don't know if anybody knows. Drake's equation came later than Fermi's argument (in 1961). Actually, I think Drake's equation is a more promising ground for estimating the chance of there being intelligent life forms, among other things, precisely because, although ambitious, it's a much less assuming parametrization of the probability, rather than an equation or a "closed" calculation. There is room for re-estimating the factors as we learn more about the phenomenology of galactic (or extra-galactic) solar systems. Plus the last factor is, if I'm not mistaken, the probability that a civilization will be able to send signals, rather than travel to Earth, which significantly increases the odds. Fermi was concerned with interstellar travel, AFAIK. The detection of signals with a message in them will probably be the first evidence, if there ever is one, of some form of intelligent life besides us in the universe, rather than the flight of UFOs. But here's the bad news, IMO: Take a look at this table with time gaps separating the appearance of new levels of organization: First prokaryotes (from Earth's formation): 1 billion years First eukaryotes (from prokaryotes): 800 million years First multicellular eukaryotic organisms (from single-celled eukaryotes): 2 billion years First intelligent life (from multicellular eukaryotes): 700 million years Average for the appearance of a new level of organization: 1.125 billion years Now suppose there's a planet out there with something like eukaryotes (cells with a nucleus). You're going to have to sit there waiting for 1.1 billion years for you to see anything interesting to happen if the above table is anything to go by. That's the problem.
50. 2 points

## Malaria 'completely stopped' by microbe - BBC News

You beat me to it. I was going to post this under the title "Good things can come in small packages". The annual death toll from malaria runs just under half a million. Great to see a potential solution. Some more information on malaria in general here. (It's from the WHO, so Trump supporters should look away now.)
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