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Showing content with the highest reputation since 09/21/20 in Posts

  1. 4 points
    Perhaps you’re right. I do find it interesting how through the years though, almost no matter the issue, you seem to find ways of placing all ownership and the entirety of responsibility for outcomes solely at the feet of Democrats.
  2. 3 points
    A lot of the topics in computer science is about getting help with programming or specific languages and implementations. Should we have a section for "programming help" or similar? Fictive examples to illustrate: Computer science existing section: Focus on the science and research aspects - Here is an interesting paper on the mathematics behind a new set of algorithms. - According to this paper cloud computing requires a paradigm shift for XYZ, what are your experiences of this? - Why does machine learning algorithm X outperform algorithm Y under these circumstances? - I have question regarding complexity theory and computability: ... Computer help section: general help with equipment and software, not so much about programming or systems design. - Have you used "specific Research/engineering software"? Do you have an opinion on suitable hardware? - I have an issue with installing this version of Linux Programming and software engineering help: (just and example name) - Why does this program fail? - In this language, any opinions on library X vs library Y? - How would I implement X in programming language y? - Why is it a good practice in to... In my opinion the general quality of content in the computer section not as high as in for instance physics. The above suggestion is an attempt at addressing that; maybe more science-related content will be contributed if discussions are not too diluted by basic programming issues?
  3. 3 points
    Reminds me of a fix we did a long time ago at my parents' place. We dug down to a broken pipe at both ends and guided a slightly smaller hose through the pipe. That worked since the pipe had a larger than required dimension and the pipe wasn't too long.
  4. 3 points
    Since michel123456 just asks the same questions over and over I think I will look through his threads to copy and paste the answers to his questions to one post. I can then number the answers so that when he asks one of his group of repeating questions you can just write down the number. It will take some time up front but in the long run it will save time for everybody.
  5. 3 points
    This reminds me of a quote by Robert Heinlein: “Expertise in one field does not carry over into other fields. But experts often think so. The narrower their field of knowledge the more likely they are to think so.” van Flandern got his degree in Astronomy, specializing in celestial mechanics. Yet he thought this expertise carried over to understanding the nature of gravity itself.
  6. 3 points
    Evolution of a Physics problem through the ages... WHY DID THE CHICKEN CROSS THE ROAD ? Aristotle: It is the nature of chickens to cross roads. Isaac Newton: Chickens at rest tend to stay at rest, chickens in motion tend to cross roads. Albert Einstein: Whether the chicken crossed the road or the road moved beneath the chicken depends on your frame of reference. Werner Heisenberg: We are not sure which side of the road the chicken was on, but it was moving very fast. Wolfgang Pauli: There already was a chicken on this side of the road.
  7. 3 points
    Fate is a strange dice that we do not control. We jump and try our best. I was born very poor. A family of survivors from the Second World War purge, not a Jew, nor a Kossac, not a Gipsy but part of them, só, no sides to shelter my grand parents. I was borm very poor and remeber starving. Brasil is not for amateurs! On the other side, the college is for free and you can get food and some clothes, só, I could attend the university amongst very rich kids. Do not know how but my grades very high enough to be there. It was a game, like jumping a circle of fire. Maybe I was able to jump but, after some jumps, there was nothing but stress, poverity and decepcion. I am not telling a personal history as if it were a glorious fight. I saw fights in my place. Native fight against miners, againt diseases. I saw poor girls fighting against misery and winning all the odds in an “male world”. I like Carlos Castañeda books. Once I was told he is totally fake but I like Don juan most of all and Don Juan says that a warrior must grab the 1mm³ of chances he/she got. I am very pragmatic. I do not mind my role in that teather. I am going to do my best and extract the fully joy of that act. I believe we are very talented and able to do the best face to the rules of the game we have to play I know people that cannot be that clever. I know people that complain the husband they choose (there is no arranged matrimonies im my place for 200 years!), they complain the age, no matter how old are they, the lack of courage or the lack opportunities, spite you spare them the best piece of that play. You are a warrior and I sense that. Just wanted to say that I know you did the best and grabbed all the chances. Best /\/ /\/
  8. 3 points
    That's a very big positive. The way I see it, academia advances in small steps. It is of course necessary, and immensely valuable. But perhaps the most significant big leaps are taken by people who are carefree, driven by an honest need to understand. They connect many more dots. They have time on their side. That's what I believe.
  9. 2 points
    https://www.nytimes.com/interactive/2020/09/27/us/donald-trump-taxes.html
  10. 2 points
    I suggest some research, even Wiki, of the Greece-Turkey tensions and conflicts, especially the Cyprus situation. It has briefly turned 'hot' a few times, but it is exactly because both are members of NATO ( Turkey is NOT EU ) that pressure could be brought to bear and hostilities stopped ( but tensions remain ). Similarly if Canada were attacked, the UK is duty bound ( NATO treaty ) to come to our aid, along with the US, France, Germany, Italy, Spain, and the rest of the 30 odd member states, including Poland, Hungry, Greece, Turkey and all of the former Yugoslav states. And no, Hungary was not part of NATO in 56, but of the Warsaw Pact. Australia and New Zealand, on the other hand, belong to SEATO, to which the US and UK were also signatories, but it hasn't been as successful' as NATO; it doesn't have its own headquarters/command and member states like French Indochina and Pakistan have dissolved or left. I would stress that NATO ( and to a much lesser extent SEATO ) is the military alliance since shortly after WW2, while the EU grew out of economic ( strictly ) European alliances that were formed during the 50s, and which C DeGaulle tried desperately to keep the UK out of ( until the 70s IIR ). It is NATO that has contributed to the peace; an attack on any member state is an attack on all of them. You don't think it was the EU that stopped Russian expansion of the Warsaw Pact ( more accurately Warsaw Occupied Possessions ) westward, do you ? The UK, as an independent state, will continue its downward spiral to irrelevance ( along with the other former European Great Powers ) in the face of competition from other resource rich states, like Russia, China, India, Brazil, and the North America block. A United Europe, though, has clout, power, and can't be pushed around by anyone. The UK could have remained a part of SOMETHING, instead you guys voted to become irrelevant, and go begging to others for trade deals. I can't wait until Prometheus has an opportunity to vote on re-joining the EU; hopefully the rest of you come to your senses in sooner than 20 years.
  11. 2 points
    Isn't that just tricky word play to get around the rule of "no guesses"? 🤪
  12. 2 points
    Except that Britain along with Vietnam, France, Japan, China and later the US were all involved in the Vietnam war. It's interesting how Brexit talks are influencing the Irish-American vote. All thanks to our 'special relationship'. As for chlorinated chicken, the House of Lords have recently blocked the move to import food that yields lower (than our current) animal welfare standards... https://www.independent.co.uk/news/uk/politics/brexit-food-standards-house-lords-government-deal-b537450.html
  13. 2 points
    If the handedness of the glucose molecule they use/produce was different to that on Earth, that would confirm a different origin.
  14. 2 points
    You could pump some gas like butane into the pipe and then walk around where you believe the pipe to be with a gas detector.
  15. 2 points
    Strange: Yes, and they're all impeckable.
  16. 2 points
    No, this is a common misunderstanding. Spacetime in a uniformly accelerated reference frame in otherwise empty space is perfectly flat - acceleration is not a source of spacetime curvature. Only distributions of energy-momentum (like planets, stars,...) are. Physically speaking, the defining characteristic of a curved spacetime is the presence of tidal gravity - however, if the reference frame in question is small enough, these tidal effects become negligibly small, which is why in a small local area only uniform acceleration looks like a uniform gravitational field. This is just the equivalence principle, and this is somewhat akin to the surface of Earth looking flat so long as you only look at a small enough section of it. Anyway, the upshot is that a uniformly accelerated frame in otherwise empty space has no spacetime curvature (the Riemann tensor vanishes).
  17. 2 points
    Well, this is just blatantly wrong. As a whole the European standards have raised the norms in the UK. Despite all the shortfalls, the EU norms as a whole are some (if not the) most developed in the world (and incidentally, the UK was heavily involved in developing these standards). The overall fear is that after Brexit the UK may result in less safe food. The issue is that as I mentioned, there are no fixed regulatory measures to create safe food pipelines. Rather they have been developed following EU directives in what is considered safe food. If now other pipelines are admitted, it may create a mix of procedures that as a whole become less safe. Another issue is that now UK has to develop new internal regulatory structures, for which it used to rely on EU systems. Likely it will stabilize at some point. But there is likely to be a state of uncertainty for some length of time at which issues such as food safety will remain unresolved. With regard to chlorination, I should add that I think I saw a paper somewhere indicating that chlorination is actually not a great measure as it does not sufficiently reduce the pathogen load, rather it seems that it just makes it harder to detect them. I feel that you are quite misinformed when it comes to UK EU relations. First, the Galileo signal services are free for everyone to use (outside the specialized defence applications). However, what has been said is that UK-based companies will not be able to tender for the production of new satellite components (and also are not allowed to participate in the development of the secure services). This is because the project is and remains an EU initiative. Also when it comes to the budget, the UK has invested about 12% of the budget but won about 17-19% of the budget back for industrial and research contracts. I.e. the UK was a net beneficiary of the project (https://www.nature.com/articles/d41586-018-07734-x). I mean, we could go through each of these claims, but I think at some point it is time to step back and revisit some basic assumption regarding the benefit-cost situation between EU and UK.
  18. 2 points
    I'm voting for appallingly cynical. Just because you feel that way doesn't mean the rest of us do.
  19. 2 points
    I don't see what the problem is. D Trump was right. Large portions of the American population HAVE developed 'herd mentality'.
  20. 2 points
    Boiling point of compound is not constant and depends also on pressure. So you can try lowering pressure to boil excess of water. It is widely used method: https://en.wikipedia.org/wiki/Vacuum_drying ..with ready to use equipment: https://www.google.com/search?q=Vacuum+dryer (anyone serious about chemistry should have a vacuum pump anyway)
  21. 2 points
    I have to advise caution in the interpretation of food-borne disease illnesses. Countries have different ways to identify and quantify outbreaks and one cannot easily just look at the raw data. There is also a difference between severity which makes it even trickier. One way to normalize the data is to calculate disability adjusted life years (DALY), which basically is an estimate of years lost to ill-health or death. From there and using WHO data there is not a vast difference between the North American region (USA, Canada, Cuba, 35 DALY per 100,000 ) vs Western Europe (40-50 DALY per 100,000; I do not have finer grained data on hand). While there are significant differences in the type of diseases. there is not a huge difference when it comes to Salmonella infections. In fact, it is slightly lower in the NA region (9 vs 12), though it is difficult to disentangle the effects of animal handling, food production, impact of chlorination and the health care system. However, the point is that it the calculated health burden are the totality of all these measures. I.e. it is possible that without chlorination the DALY might increase in the US, which would indicate that Europe is doing something better without the need for it. Or it may not make a difference, indicating that the practice is useless. But the tricky bit is really finding which elements in the whole chain are really protective, especially as certain elements may rely on other part of the whole thing. So as a whole it is not trivial to state whether the whole food chain is safer in Europe vs North America (or even US specifically). Each regulations seem to keep the burden of food-borne diseases somewhat similarly in check, but there are also other benefits when it comes to different approaches in regulating the food chain. But again, I think direct comparisons are difficult, not least because rules and regulations in each region are not necessarily based on best science, but rather a quagmire of heavily politicized historic rules, regulation and practices. With increasing globalization the food supply chain has become even more complex and I have severe doubt that regulations are keeping up.
  22. 2 points
    The EU is big enough to tell the US to stick their chlorinated chicken where the Sun doesn't shine. Post Brexit, the UK will be over a barrel and will have to accept pretty much any offer that the US makes. Anyway; Biden wants the Irish American vote (or, at least, doesn't want to upset them) so it's perfectly sensible US politics for presidential candidates to have a clear view on ensuring the future of the GFA. Since Borris' plan to break international law puts that agreement at risk, it's sensible for any other country to have a view on it. Most countries would prefer to maintain the GFA. If you are Mr Putin- or one of his supporters- you might want to sow discord at the boundary of Europe in order to make Russia look good by comparison. In that case you would want Boris' plan to go ahead. The same would be true for other rogue states with an interest in undermining international law and cooperation.
  23. 2 points
    One of the few things you've said I wholeheartedly agree with.
  24. 2 points
    I think there is no clear answer to that. Studies basically are looking it from two perspectives. One mechanistically, which looks at virus survival in droplets and ejection and the other is epidemiological where folks look at likelihood at being infected outside. From the latter viewpoint, it appears that casual outdoor infections are very rare and mostly connected with folks being close to each other. Mechanistically, evidence suggests that e.g. in saliva it would take minutes for sun-inactivation of SARS-CoV-2 (~6 minutes for 90% inactivation), so at least theoretically if someone sneezes in the air and you run straight through it, you might get exposed to active particles (sneezing on the ground would arguably be safer). But again, most evidence suggests that overall infection chances are low under these conditions.
  25. 1 point
    Do you mean the observer who is at the same place as the blinking light? Yes indeed, for him the interval is simply whatever he reads on his clock. It would seem to me that Y will be spatially removed, i.e. up in orbit above the tower...? Perhaps I misunderstood. I can't give you a straight answer to this without having done the numbers, since this scenario mixes relative motion with a curved space-time background, so calculating the geometric lengths of their respective world lines isn't trivial. Z isn't a geodesic, because he is launched up, so he undergoes acceleration. Yes, indeed. The maths here aren't overly complicated, but they are definitely tedious. I am not sure I follow you. Are you essentially saying that, if you somehow introduce a gravitational source into a scenario that was hitherto flat spacetime, then the spacetime interval will be affected by this? If so, then you are correct. Both is correct The interval is usually written as a line element, which is an infinitesimally small section of a world line: \[ds^2=g_{\mu \nu}dx^{\mu}dx^{\nu}\] This is a local measure, and it is covariant under appropriate changes in coordinate system. The obtain the geometric length of some extended world line C in spacetime, you integrate this: \[\tau =\int _{C} ds=\int _{C}\sqrt{g_{\mu \nu } dx^{\mu } dx^{\nu }}\] This is a standard line integral, and it can be shown that it is also a covariant measure. Hence, all observers agree both on the line element, as well as on the total length of some given world line. There are always infinitely many possible world lines between any two given events, in any spacetime. Generally speaking though, only one of them will be a geodesic (unless the spacetime in question has a non-trivial topology). Yes, it is a function of the metric, see expression above. I think I lost you here, I am not sure what you are meaning to ask...? In SR, there will be one unique geodesic connecting two given events (that's an inertial observer travelling between the events), and then there are infinitely many world lines that are not geodesics (corresponding to observers who perform some form of accelerated motion between the events). Yes. When performing coordinate transformations, the components of a tensor can change, but the relationships between the components do not, meaning the overall tensor remains the same. I see what you are saying, and whether or not this is a mathematically rigorous deduction is a good question. This is probably better posed to a mathematician. I am hesitant to commit myself here, because I can think of other quantities where this is not true - for example, energy-momentum (in curved spacetime) is conserved everywhere locally, but not globally across larger regions. The geometry of spacetime near a binary system is not stationary, and the overall spacetime isn't asymptotically flat either, because of the presence of gravitational radiation. The geometry will be slightly different each time the binary stars complete a revolution. There really isn't any way to define a consistent (!) notion of 'gravitational potential' that all possible observers could agree on.
  26. 1 point
    Here are some examples from my experience. If it's maximum money you want. I have a friend who started his business from my front room and became a millionaire. He said to me "If I work as an engineer (as part of a team) I can only make the wages of one engineer." "But if I supply engineers to many clients at a %, I am not limited by the wages of an engineer, just the number of engineers I can supply" On the other had in the late 1960s, an aircraft design company (Rotax) want to test the idea of teamwork with either a mix of specialists or groups of specialists of the same discipline. So they gave these groups the task of designing and producing a safe control for two wing pumps, A and B. The point was that the aircraft power supply was inadequate to start both pumps at the same time, although it could run both together once started. Most machinery is like this it takes more power to start them than to run them. The mechanical engineering group came up with a complicatd mechanical interlock between switch A and switch B. The electronic engineering group came up with a fancy digital circuit board electronic version. Both were tested by simultaneously jabbing both switches by hand. Both failed. The lone genius came up with a simple single two position switch labelled switch on A , switch on B. In the offshore oil industry it takes teamwork to move a laybarge or an oil rig. One is moved by a team of tender tugs shifting anchors and onboard winches, The other by towing with a team of tender tugs. However it takes a talented individual to set one of these tugs alongside an oilrig, laybarge or service jetty.
  27. 1 point
    The correct word is "different". In the US, it's the custom for people shopping for clothes to take them from the rack into a dressing room to try them on. We don't have to ask first because in the US, "the customer is always right". In France, it's considered polite to ask the shop keeper first, because it's their store and they're the expert. Different societies (with different languages) have different conventions for behavior. Some languages can sound harsh to foreign ears. People speaking German often sound angry to me, while people speaking Arabic or Cantonese often sound excited. I think that's just me trying to make someone else's speech patterns fit my American English sensibilities. How we deal with accents is cultural as well. I grew up watching movies where the villains spoke English with German or Russian accents, so folks who speak like that can be intimidating. The posh British accent is almost branded in the US as "intellectual".
  28. 1 point
    Have you noticed the red dots by your right hand? They seem to be in a similar position relative that side's headlight ie at about 1 o'clock.
  29. 1 point
    It seems to be pretty awesome looking camouflage... https://www.sciencedaily.com/releases/2011/04/110425120344.htm#:~:text=A team of researchers at,hindwings that are folded underneath.
  30. 1 point
    The funny thing is, he's already accepted that a Doppler effect is acceptable in his definition of reality, and it's an easy modification of a twin paradox setup to make neither twin inertial and make it truly symmetric. Then just say "that's what they both see." It's also funny because for me, seeing the asymmetry in the Doppler analysis of the twin paradox is probably what fully sold me on the predictions of SR, and I never doubted the resolution of the paradox after that, even though I still would have struggled with "the Earth's clock jumps forward with the traveler's change in inertial frame." Then if you cherry pick some predictions of SR, you can get something that fits Michel's reality and doesn't add up (which is not a problem for Michel). For example, if you let the traveling twin have a lightyear-long ruler attached behind it, and you make it so the entire ruler stops simultaneously in Earth's frame, then you can see something like this: Say v=.6c, from Earth the receding ruler appears compressed by the Doppler factor of 1/2. Then when the 1 LY mark on the ruler reaches Earth, that part of the ruler stops, but the traveler appears to keep moving until it reaches 1 LY rest distance. All along the ruler, a "wave" of successive lengths of the ruler being seen coming to stop and returning to normal length spreads down the ruler, the wave moving at an "apparent rate" of c, so that it takes 1 year to see the traveler and the end of the ruler coming to a stop 1 LY away. That's something SR predicts and sounds similar to what Michel has described the traveler seeing (instead of SR's prediction of the traveler seeing Earth's entire ruler appearing normal instantly, when the traveler---not Earth's ruler---stops and comes to rest in Earth's frame). I'm not positive I got the details right. Course, you'd have to sell your soul to argue that the predictions of SR describe reality and show that SR is wrong.
  31. 1 point
    What is wrong with you? Seriously, what is wrong with you?? You ask the same questions and get the same answers. Wierd, isn't it? Why do you think the answers to your questions are consistent? Your not satisfied with the answers, but for some reason nobody will change their answers to satisfy you! I guess you will just have to keep asking the same questions; the answers are bound to change eventually and satisfy you, right?
  32. 1 point
    Dandelions and Homo are genetically similar enough to be connected, but that doesn't mean that either is descended from the other. It just means we share a common ancestor at some point. The more recent that common ancestor, the closer we are related to a thing.
  33. 1 point
    It is a bit sad that "never again" was just a pretty lie. I understand what you are saying and just focusing on the major member states is a rather narrow view. However, I think it is quite clear that the overall point was that the EU was instrumental in avoiding a continuous conflict between these member states, resulting in the longest peace period between those nations.
  34. 1 point
  35. 1 point
    Maybe we should add some unsourced ones and have a guess who? "Here is a helpful animation displaying the relativistic effects when a chicken crosses the road, as seen from a stationary observer." "The chicken crossed the road in 18.3400000000021 seconds, measured in the chickens frame of reference." "No model. No math. You have no theory. Your idea how the chicken crossed the road have been debunked over and over. Thread closed!" "A charged chicken crosses the road at an angle of 90 degrees, in what direction will there be a magnetic field?"
  36. 1 point
    Adding to that: A ruler doesn't measure "accumulated" distance, but an odometer does. While a twin makes a round-trip at constant speed, if its clock records half the time Earth's does, it will measure that it traveled half the distance Earth measured it traveling. Its odometer retains the accumulated effects of length contraction. (The trip's clock and odometer dicrepancy ratios would generally differ is the speed wasn't constant.)
  37. 1 point
    ! Moderator Note After some staff discussion, we have decided that this thread is now the only place where michel123456 may discuss topics related to time and relativity. As such it has been split from the parent thread and placed in speculations.
  38. 1 point
    Well, yes, I am aware of the Anchor butter brand. It is made in Wiltshire. https://www.dailymail.co.uk/news/article-2569867/Anchor-New-Zealand-butter-Wiltshire-Brand-owner-breaks-tradition-120-years-moving-production-UK.html The rest of your post seeme equally devoid of evidence or rationality. Plainly, no. I was involved as a UK representative, ensuring that the science was good. You understand what a veto is, BTW? Fuses are meant to fail- that's their job. And "a fuse must have gone" ia a staple of detective stories far older than the EU standard. No, but thanks for clarifying how much attention you are paying to the facts. So, it's the "availability "cognitive bias that's at work here. Always good to know. No. If it was then this wouldn't be 15 pages. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/869232/marketing-standard-apples.pdf You do realise that, if the UK farmers want to sell apples in the rest of the EU, they will still have to meet the EU's criteria? But they will no longer have any influence over them. As I said, I don't see that as taking back control. I see it as recklessly abandoning a right to veto bad EU decisions that might harm the UK's interests. One side only had lies, but they had better funding. And you are still rehashing those lies; in the face of reasoning. And the wheels have come off the lies. The majority now recognise that it was a mistake. https://en.wikipedia.org/wiki/Opinion_polling_on_the_United_Kingdom's_membership_of_the_European_Union_(2016–2020) But Boris won the election on the back of it and isn't he doing a grand job (worst death toll in Europe in spite of being an island. It's almost as if he forgot that we "took back control of the borders"). You do realise that discussion forar are social media, don't you? They don't need to be common; they could be as rare as this one.
  39. 1 point
    Steve Bannon is one of the many folks who started to weaponize social media in order to influence politics throughout the world. One of the interesting bits is that he himself is not a state actor (such as Russia, who also interfered in various political campaigns in an effort to destabilize European countries). It can also be said that after initial success following the refugee crisis, many of the other campaigns kind of faltered (not least due to the ineptitude of many of the far-right political groups). Nonetheless, Europe has seen a stronger polarization and an overall move to the right over the last couple of years. You could say that. After all, xenophobia is a powerful tool that is associated with the rise of numerous populist movements. It is easier to paint a picture of roses by changing things. Remainers, especially if being honest realistically could only offer business as usual and indicate the economic harm of leaving. So on the hand you have folks stating that if you leave you get all the benefits, none of disadvantages, somehow have simultaneous access to all markets but not following any of the requirements and you get to get to keep the pesky Polish plumbers (who are the only ones offering to show up in the first place) away. The only potentially real benefits in the long term depend quite a bit on rather difficult to assess (such as driving policies that are separate from the EU market), but most I have seen so far are very speculative, whereas most studies do show a clear net negative. It can be said that some of the losses are lower than projected initially. However, the UK did not actually properly leave yet, either.
  40. 1 point
    When you pass a unit time-like future oriented vector to both slots of the Einstein tensor, you get a scalar that is just precisely the average (!) Gaussian curvature in the spatial directions within a small neighbourhood. So the Einstein tensor is a measure of average curvature around an event. In vacuum, geodesics will diverge in some directions and converge in others, in such a way that the average balances to exactly zero - hence the vanishing of the Einstein tensor in vacuum. Indeed - it’s average Gaussian curvature, and thus it captures only a particular subset of overall Riemann curvature.
  41. 1 point
    ! Moderator Note You were told to give this a rest
  42. 1 point
    I would think your parents left you something much more valuable than an inheritance Area54. They left you valuable life lessons, like caring and getting along with your siblings, and anyone else you care about. Dig deep Charles, your cynicism may have buried those same lessons your parents taught you.
  43. 1 point
    No, it's not. Length and time contraction are some kind of foreshortening. But the angle analogue is v/c, and it's based on the geometry of a hyperbola, not of a sphere (or circle). But never mind that now. And it is an observer-dependent effect. If for some reason you are thinking that the object you're looking at doesn't have the length you seem to perceive, you may choose to change the angle and you'll see something different. But exactly the same as the foreshortened arm has a proper length (invariant), moving objects have a proper time (their co-moving time). About 'twins' trips: Exactly the same as you can go from one corner of a square 9 m² room (of 3 m-wide walls) to the contiguous one along the wall, measuring a distance of 3 meters, you may decide go to the contiguous corner the long way, by sequentially covering the other two corners, and cover 9 m (3+3+3) around the other direction. That's exactly the same that happens to the non-inertial twin that went around to the same place on a non-inertial trip. The first twin has gone along a flat wall and has noticed nothing significant. The non-inertial twin has had to cross two corners and has noticed curvature. I'm not sure I'm helping with this alternative explanation. If not, feel free to ignore me. I'm amazed by the patience displayed here by almost everybody else here, TBH. They don't give up on you. They just don't. I confess my inability as of today of concocting such careful and detailed Alice-Bob analyses as have been offered to you. I have a tendency to search for shortcuts. Edit: Rather than shortcuts, to concentrate on the formalism and learn to relax about puzzling un-intuitive notions. I do mistrust my intuitive notions.
  44. 1 point
    You are correct. You could modify it to have a final state somewhere that transitions on some other letter like c? A DFA must end on a final state e.g. the 2 circles. Starting from q3 you can accept aa as it will transition to q0 then q1. Starting from q1 you can accept bb as it will transition to q0 them q3. You can read more than one letter at a time and make all final states lead to an exit state if it reads them. You can use anything that fits in combinatorial logic including don't care terms to read a regex e.g. BxBxxxB. ***** Challenge Question ***** A DFA is a part of a Turing machine. Show that a 3 head Turing Machine can accept the regex B*B*B without changing state by creating a table of moves. Hint. You may stop moving a read head if you read a letter.
  45. 1 point
    So the concern is getting salmonella from food, and yet you don't want the food to be treated to reduce the risk from salmonella... In any event, not all US chickens are treated this way, and surely individual transactions can be arranged so that the imported chickens are untreated. AFAIK trade agreements simply define the parameters and regulations of commerce, they aren't the actual commercial transaction. The agreement might allow for chlorine treatment, but does it mandate it? If <UK food conglomerate> wants to import chicken from <US chicken packager>, they can agree to any details not forbidden by the applicable laws. You don't want chlorine treatment? Put it in the contract. To use an example, it seems to me you could import kosher or halal products, which would demand the products were prepared in accordance with the appropriate procedures, above and beyond any basic trade agreement. I suspect that would make food poisoning worse, not better...
  46. 1 point
    Not attempted because we can't get stuff that massive to move that fast. But we've done the equivalent in particle accelerators, as Halc has said. if you get a proton up to 1 TeV, it should be moving about 45x the speed of light according to Newtonian physics. The easiest effect to measure is on time, and we have done multiple tests that confirm relativity, the most obvious of which is GPS. That you are ignorant of the experiments and technologies that confirm it carries no weight in any discussion. This is criminally naive. ! Moderator Note Split from original thread, which was asking about Newtonian physics. Hijacking, and also an argument not made in good faith. Please stop doing that.
  47. 1 point
    It is not as simple as less trees equals less fire risk; mostly it is the grass and undergrowth and leaf litter that burns most readily in forest fires, not usually trees. Fires are extreme when forest canopy (trees) burns - and that is more likely when the intensity of lower level fires is enough to carry the fire to tree tops. Eliminating "ladders" of fuel from ground to canopies is often a priority for fire hazard reduction. Taking out trees usually results in an increase in fuel, from the treetops - the branches and leaves that are not usually harvested - as well as increased growth of ground vegetation. Dense forest canopies can result in less ground level fuel and fire risk, depending on forest type. Local conditions vary greatly. Hypothetically the tree tops could be harvested too, but boilers made to burn wood may not be suitable for burning leafy material, which may be better done through gasification (heating without burning, to produce flammable gases). They present harvesting problems compared to logs; little or no existing equipment or infrastructure compared to burning sawn or split wood or chips. And if there is insufficient demand for that kind of fuel - or the costs are too high - then subsidy and regulation would be needed to make it happen. Relying on forced labor may not be the best way to do things that are hard - it usually isn't efficient. As a fuel that can replace large amounts of coal burning? I'm not sure it cannot be done at large enough scale to be a large part of our energy supply; there are better (competing) options as well as competing uses for wood - and the question as posed represents a transition, from dense forest to thinned, that stops when the intended outcome is reached. Permanently displacing fossil fuel use requires trees to regrow.
  48. 1 point
    That simply isn't true. Some kids have parents that don't give a damn, they drink or have problems with drugs or money. Some schools have outdated textbooks, broken laptops and no or limited access to the internet. https://www.nytimes.com/2018/04/16/reader-center/us-public-schools-conditions.html Some students don't have the internet at home or have very bad internet and only reference books. Some families need help at home and take kids out of school to help out on the family farm or are forced to help out on the farm after school. https://www.dailymail.co.uk/news/article-6728209/Children-skipping-education-help-family-farm-drought.html Some kids don't have access to extra curricular activities like sports or music. https://www.theatlantic.com/education/archive/2015/01/the-activity-gap/384961/ Some kids don't have access to tools and equipment required to study certain activities. One example could be a student in my school built a wooden boat as a school project from wood and tools his family had just lying around and got an A1 in the woodworking class. I had little to no tools at home and barely got a C. But it gets worse. Some kids have access to tools like Unreal Engine because their parents can easily afford computers capable of running. For a long time I didn't have a computer that could run unreal engine at all. Then there is the university places gimmick. Access to university is controlled by a points system. The number of places puts people in their boxes. Poor people do the low paid courses and rich people do the better courses. There is some allowed movement between rich and poor but really the government doesn't want too much change. If poor people start to do better then the points increase. https://www.theguardian.com/education/2020/aug/13/almost-40-of-english-students-have-a-level-results-downgraded
  49. 1 point
    Apologies if it came across like that, that was not my intention. I do of course realise that not everyone has religious or spiritual aspirations, or feels any need for those; also, for any given person these inclinations can change over time as life happens. All of this is perfectly fine; religion is not necessarily required to gain an understanding of the human condition. I think what I was attempting to say was that for many people religion/spirituality can be a very helpful tool. But of course (just like anything else) it can also become a trap and a source of enormous suffering, if it is related to wrongly. I personally think this is too simplistic a way to look at it. Of course, most people will relate to their religion in just this way - they attach themselves to their respective outer forms, teachings, rites and rituals, and leave it at this. That’s indeed a “lazy” way of engagement, and requires little else but blind faith. The problem with this is of course that it is not actually transformative, in the sense that rarely does it provide any answers and insights that go deeper than surface level. This is the archetype of your Sunday church goer who shows up for mass, and then goes back to his normal life unchanged and with their same vices, habits, and sufferings. If one seeks real answers to real existential questions, then a far deeper commitment is required; this is why Christian mystics went into the deserts to seek insight, why Buddhist hermits spend decades meditating alone in the forests etc etc. You get the idea. Religion is like a vehicle that can potentially get you to a place of deeper understanding...but that requires deep commitment and lots of effort. You get out exactly what you put in, and that is really not unlike what happens with science. It’s just that the questions that are being asked are different ones.
  50. 1 point
    The Society for Neuroscience, along with The Kavli Foundation and the Gatsby Charitable Foundation, maintain a site that has information accessible to the layperson and is probably a good place to start for an answer to general questions about the brain. An excellent go-to source if you are generally curious about anything brain-related. One thing I do like in particular is the way it address certain "brain myths" that people hear and wonder if it is true (there is a hyperlink at the top of the page that says "neuromyths" as of the date I made this post): http://www.brainfacts.org/
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