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No, it's not the accelerations at the start and finish of the journey that's responsible, but the acceleration in the middle corresponding to the travelling twin's turnaround. An interesting approach to the twin paradox is to consider not time dilation but Doppler shifts. While each twin is seen to be moving farther from the other, they appear redshifted, but while each twin is seen to be moving closer to the other, they appear blueshifted. However, the two twins do not see each other symmetrically. For the stay-at-home twin observing the travelling twin, the change from redshift to blueshift occurs after the light from the travelling twin's turnaround has reached the stay-at-home twin. But for the travelling twin observing the stay-at-home twin, the change from redshift to blueshift occurs immediately at the travelling twin's turnaround. Thus, the travelling twin sees the redshift and blueshift of the stay-at-home twin for equal times, whereas the stay-at-home twin sees the redshift of the travelling twin for a longer time than the blueshift.

Observed on my recent trip to Scotland:

If your intent is not merely to stir the pot as so many thousands of good little Chinese and Russian trolls are doing right now across the internet in a directed attempt to sow division and discord during a US presidential election, then you should clarify what discussion you wish to have here around this.

It’s not all that broad of a brush. White Christian Nationalists (White+Christian+Nationalist) is the intersection of three groups. It does not imply that all whites, or all Christians, are nationalists.

Sounds like the replies we hear like “all lives matter” in response to reminders that “black lives matter.” It ignores the underlying baseline and status quo where equality is very much not already present. Is mental health important for all? Of course! Are there reasons mental health might be harder for women? Of course! When’s the last time you had to accept 80 cents on the dollar for the same work? When’s the last time you got accused of being a DEI hire or slut shamed and accused of sleeping your way to the top even though you were twice as smart and worked twice as hard as everyone else? When’s the last time you had to question whether it was safe to be alone at a gathering where everyone else was a different gender from you? Yes, mental health for all is important, but not everyone is working from the same starting position. See also: Hatred and violence shown toward LGBTQ communities. There’s good reason we tend to focus more on mental health for them than middle aged entitled white men with a fluffy 401K. https://morganemichael.com/for-educators/middle-school-resources-grades-6-8/privilege-and-empathy-lesson-how-your-socio-economic-position-impacts-how-well-you-do/

It’s illegal to laugh out loud in Hawaii. You have to keep it to a low ha.

You're doing horribly. You're intellectually dishonest and you have no inclination towards learning anything of substance. You seem entrenched in your confirmation bias, and can't reason your way through the scientific replies you're getting. You somehow think this is a competition rather than an opportunity to educate yourself. We're used to people coming to a science discussion forum to learn. It's not as common to have people join and then insist that their opinions and wild ass guesswork are equivalent to the knowledge accumulated by scientists over the centuries. You act as though education was a punishment your were able to avoid, rather than a goal you missed. I'm sure you're a lovely person IRL, but here you come off as willfully ignorant, which is shameful and wastes everyone's time. People here have studied intensively, and love sharing the knowledge they've gained, so your posts are often insulting in their lack of understanding and civility. You're more curious about what our "red line" is than about science, and that means anything you say from here on out will be in bad faith. Let's just part ways now. There are plenty of wild ass guesswork forums out there for you. This site requires more rigor than you're willing to give, but I guess that's our fault? Goodbye.

There was a geek T-shirt joke about this topic 151.194.25.39 —> is a Public IPv4 address quad. 127.0.0.1 —> is the special ‘Loopback’ address for your own computer on a LAN. 19:08:AF:51:11:08 —> is the MAC or ‘Ethernet’ hardware address of your device in hexadecimal.

As I was leaving the art museum, I got arrested for stealing a painting. I don't understand. Earlier when I asked the guide if I could take a picture, he said yes.

Not all men do, and as Charon noted there’s a larger global trend occurring whereby divisions are getting more pronounced between men and women. It’s sometimes more a predictor than income level and education. In my small universe, they tend to be tech bros. The types who think Joe Rogan and Elon Musk represent the ideal (or who join sites like ours to defend incels, for example). It’s not local to Trump, but is absolutely being reinforced on social media and information bubbles. And with our insanely tight county-by-county voting within the long outdated slavery-protecting electoral college system, those tiny changes in turnout and choice at the margins matter quite a lot.

Metabasite is a broad term for a metamorphosed basic (ie. low silica) rock. If that low silica rock was originally a basalt (as in this particular case) we can be more specific and call it a metabasalt. The terms aren't exactly synonymous, but ... A lot of these newer terms have appeared due to the modernisation of rock type systematics that the BGS has been implementing over the last couple of decades. More at BGS Rock Classification Scheme My crib sheet for metamorphics attached. Most of the outcrops in this area have been subjected to a 'greenschist' grade of metamorphism which is typically characterised by the green mineral chlorite. I'm not 100% sure that @exchemist's blue is the glaucophane blue of 'blueschist' grade, but it's possible. Classification of Metamorphic Rocks.pdf

It is concerning the way household pets are being eaten in our cities. Springfield was essentially destroyed by immigrants eating kittens. Also raises the spectre of pets who may be legally obtaining post birth abortions. They just leave the kittens in the basket while they decide what to do with them. Clearly Harris is okay with aborting the kittens after they're born and then eating them. When has she spoken out against this? NEVER. What did she do in 3 1/2 years? NOTHING. Puppies, kittens, hamsters, gerbils, aquarium fish...in one Ohio city they're all gone. All eaten by the immigrants, basically people released from insane asylums and prisons, the prisoners either there for political crimes or drugs or....eating pets, presumably. When you come to our big beautiful country, you know that our pets are bigger and healthier and mostly plump, just easy pickings for these human vermin.

You might be able to glean a little more from Geology of the Greenock district Memoir for 1:50 000 geological sheet 30W and part of sheet 29E (Scotland). From what I can make out, the beach walk north starting at the Highland Boundary Fault near Kilcreggan will cross: 500m of Bullrock Greywacke until junction with School Road 2000m of Dunoon Phyllite until just after beach crossing of Dowall Burn in Cove 300m of Beinn Bheula Schist to just before Knockderry House Hotel 100m of 'metabasalt' before continuation of Beinn Bheula Schist This last looks to be associated with the Loch Katrine Volcaniclastic Formation situated directly across Loch Long from the hotel, which is dated to Ediacaran Age. Since the hotel is built on this formation I'm guessing it's a good candidate for the photograph.

LQG (loop quantum gravity) predicts the minutest dependence of the speed of light on frequency, which would be best detectable on large populations of high-energy photons with very long astrophysical paths. A good candidate to test this would be a very far away (=> very early) gamma ray burst. GRB 221009A stepped forward some years ago. From: Stringent Tests of Lorentz Invariance Violation from LHAASO Observations of GRB 221009A Although this doesn't totally do away with LQG, it seems to rule out a vast landscape of the LQG parameter space. The somewhat less hyped version of these news is that we are a tad surer that LIV does not occur in Nature.

Just random. Given infinite time a program that randomly prints out one letter at a time will do the same. Note that it'll be a Library of Babel situation. There's likely, though not guaranteed, to be lot of nonsense and partial texts produced as well.

No it is the lack of any understanding of Einstein's work and life that does the damage, to my mind. It's full of of nonsense such as "exciting" matter to the speed of light (impossible and irrelevant), the notion that E=mc² is some sort of key to making an atom bomb (which it isn't) and so on. Einstein never worked on nuclear fission and his contributions to physics didn't enable anyone to build one. He had nothing to do with Germany's failure to produce an atom bomb. You may possibly be confusing him with Heisenberg, who did work on the German bomb project. Einstein's sole intervention regarding the atom bomb was to sign the letter to President Roosevelt warning of Germany's capacity to build a bomb. The letter was not drafted by Einstein but by Hungarian physicists: Leo Szilard, in conjunction with Edward Teller and Eugene Wigner. In fact they had to explain to Einstein that it was possible to make a fission bomb, as it had never occurred to him. They then persuaded Einstein to sign the letter, as they rightly believed that would ensure the President would read it, their previous attempts to warn the US government having been ignored. So what your story needs, first of all, is a bit of basic research into what Einstein did and the actual history of it. And, if you don't understand the science, don't make up preposterous stuff about phasing effects and atoms lining up. Steer clear of technical details: they add nothing to the storyline in any case and just make the story look silly.

Using AI technology for the power of good, a former Google employee made all of the 900 some odd pages of Project 2025 searchable and filterable by topic area. Not all heroes wear capes. https://www.25and.me/?topics=

Four years ago, I saw clearly that this trend in jokes was coming. It was 2020. You really can't compare Canadians and Americans. In two centuries, it's only been possible to draw one parallel between them. Canadians have more freedoms than Americans do. It's because we gave them more latitude. Things were simpler 1923 years ago. That's why we start with History 101.

A brain can build purpose. A neuron can't. Purpose = "intention", "aim", "meaning", etc. What you're doing here is stretching the meaning of the ordinary word to take it outside of the specific sense in which scientists and philosophers of science use it. For you it's just a synonym of "function". In that sense, of course neurons have purpose, because you use it to mean "function". No. It's not just a question of power. It'a question of different patterns, laws, and correlations arising, which a bunch of tens of neurons cannot even begin to accomplish. You tell me. I sense a big teleological explanation coming up. Random is not just anything. It has to be consistent with patterns of quantum noise. The die analogy was just that; an analogy. Here I don't understand what you say. Maybe that's why I don't get your point. What does this have to do with purpose in ants? The constants are representations of a material universe? I cannot make sense of that. Dimensionless constants are what they are 1/137 is not a representation of anything. Had it had a very different value, there would be no mind in the sense of a part of the universe trying to make sense of the whole universe. I did: You are a dualist. Your question only makes sense if there are two different realities. Namely: matter and mind. What we call mind comes from patterns of behaviour in matter. I'll answer that when you answer this: When the Earth turns around the Sun, who is doing the computing? How does the Earth know where to go next?

Avoiding threads with exchanges such as these

On the contrary, there is increasing recognition that too much research on health matters, and consequently too much health provision, has failed to take into account sufficiently the differences between the sexes. Like many people, I detest identity politics, but health provision is an area in which there are obviously big differences between the sexes, so recognition of this is not playing politics.

This is not helpful. In many areas of health, but especially in public health there is increasing recognition that we need more fine-grained approaches to address pervasive equity challenges. To do so, one needs data with more resolution, not less. Aggregating information removes the ability to develop targeted counter-strategies. You might as well say that everything is biological so we should address all issues, mental, infectious diseases, aging, and so on just under the banner of biology. Especially, when it comes to mental health, men and women have different types of challenges and barriers and there is a cultural overlay that needs to recognized while trying to deliver care. Ignoring all that really doesn't do anything helpful and can be harmful. One prominent example in a different health area, is the high mortality of black mothers in the USA, something that would not have been noticeably if one collected data while ignoring racial backgrounds. On thing that has to be mentioned is that in the past (and to a lesser degree currently), folks have divided information along lines that were not well established and/or were colored by stereotypes. Certain types of mental health issues were disproportionately attributed to some groups, but without sufficient data to establish that this is actually the case, for example. In other words, we need more data to figure figure out where the lines really are. Which is additional work, for sure. But the benefit for figuring that out is the ability to develop new approaches to deal with challenges rather than trying (and failing) with one-size-fits all attempts.

That does not make a lot of sense. Folks would rather say that aspects of science are useful within a given realm and provide the evidence for it. "Good" is a value judgement that only makes sense by adding premises. For instance, you can say that saving lives via medicine is "good". From there you could infer that medical sciences therefore serves a "good" purpose. But there is not reason to simply accept a statement without any evidence.

I think, especially in the way that @Night FM formulates it, it is even worse: obviously only the most terrible threat, burn eternally in hell, works to keep religious people on the right moral path. Just contrast this with Zen-Buddhist ethics: there morality is a consequence of real insight in who we are. It leads to friendliness and compassion with other living beings. To say it very simple: we are all living in the same boat. @Night FM: would you, personally, misbehave, when heaven and hell would not exist? If not, why? If yes, then I consider you as a morally bad person, because you only behave morally under the biggest threat possible. Do you really need that, just to be kind to others?

Got a couple of test results back. I got a 75 on COVID, what the hell does that mean?! Also, my IQ came back positive.

Like astronomers' perversion of the term "metals", you mean? 😁

But the numbers were unrealistic, and you never used them anyway, except to attempt an invalid force relation. Using real numbers gives some plausibility to the scenario. Using exact numbers is probably not useful. To illustrate: Theia was (supposedly) 10 times the lunar mass, not 1.5 times. The extra mass either escaped (high speed object, mild glancing hit), in which case where did it go? or it hit more directly and was completely absorbed except for the ejecta that managed to coalesce in orbit. Anything not already in orbit has to be moving at a minimum of around 40000 km/hr relative to Earth, so that's a lower bound to any impact from an external object. Mass and speed do not determine force, and force is not directly relevant to the scenario. Force is different everywhere, and is not one value. Fluid dynamics must be invoked. Yes, it was an off-center hit. A straight on shot would have resulted in ejecta with minimum net angular momentum, and thus no moon that requires it. The offset hit would have significantly altered the spin of both bodies, resulting in an Earth will say a 10 hour (or less) day. How long did it take for the moon to get tide locked? Does the simulation answer that sort of thing? Certainly not until any second moon merged into just the one. You don't seem to contribute after this. All your recent posts seem focused on personal attacks against those trying to help. I suppose I will also be the eventual target of that.

Unfortunately, we keep running into the problem of new members not understanding how we like discussions to be civil. We see the negative point as shushing someone being too loud at the library, but too often they respond by yelling "Don't shush me!", which gets them more negative points, which leads them to start a thread about how petty it is to insist that people be quiet at the library.

Mamod steam engine. Early 70s. Ran on Meths and had a steering rod through the chimney.

These are all excellent points. Unfortunately I’m up to my eyeballs in the real life at the moment, so I’ll need to come back to this at a later point. Consider the following though. Suppose you have an alien scientist whose species lives down in the ocean of a water-world (no solid land). One day he notices some sand on the bottom of the ocean, and begins to wonder: what would happen if you had a very large amount of grains of sand, without water, just under the influence of wind and gravity? He knows Newtonian physics, and he knows the Navier-Stokes equations. Based on these, he figures that each grain is blown about by the wind, pulled down by gravity, bounces about a bit in pretty much chaotic patterns, and might come to rest somewhere. Over large areas and long times, each point on the sand plain is equally likely to become the resting spot of a sand grain - so it’s reasonable to expect that all inhomogeneities smooth out over time, and you end up with a more or less flat expanse of sand eventually. So now he jumps into his (water-filled) UFO and visits Earth. He lands in a desert, and imagine his surprise when he sees this: A naive application of Newtonian gravity and Navier-Stokes fluid dynamics would give no indication that a large number of essentially isolated sand grains undergoing essentially chaotic dynamics would give rise to large scale ordered structures such as these. So our alien scientist would be forgiven in concluding that there must be some other influence that leads to the formation of dunes. The situation in GR is similar. Each star or galaxy taken in isolation is locally near-Newtonian, and would thus be expected to behave that way on all scales. However, an n-body system with very large n undergoing chaotic dynamics under the laws of GR might form global spacetime geometries that are not immediately predictable, just like sand grains and the formation of dunes (which is meant just an analogy, btw). This holds for stars in a galaxy, or for the interaction between galaxies, or for galaxies in the universe. The point is we don’t know if that’s the case or not, because we don’t have the computing power necessary to model a GR n-body problem with very large n. So this is just a hypothesis, based on the fact that metrics don’t add linearly; the overall metric of an n-body system is not the sum of n metrics for the n constituent bodies. So it’s possible at least in principle that the actual global spacetime might look like it contains more mass than we can observe, even though in actual fact it doesn’t. That’s not really what I’m saying. We can use GR quite accurately so long as it is permissible to make enough simplifying assumptions to render the maths manageable. For example, a single body that can be considered isolated (asymptotic flatness) and is symmetric enough can be easily modelled, and the result matches observation very closely. I think the problems arise only if we are dealing with n-body systems, because the non-linearities inherent in GR may not smooth out and become negligible; they might in fact compound in large enough systems. And the trouble is we don’t have enough computing power to actually run such simulations, for large n.

https://www.telegraph.co.uk/obituaries/2024/04/19/daniel-dennett-philosopher-atheist-darwinist/ Daniel Dennett, the American philosopher, who has died aged 82, was, with Richard Dawkins, a leading proponent of Darwinism and one of the most virulent controversialists on the academic circuit. Dennett argued that everything has to be understood in terms of natural processes, and that terms such as “intelligence”, “free will”, “consciousness” “justice”, the “soul” or the “self” describe phenomena which can be explained in terms of physical processes and not the exercise of some disembodied or metaphysical power. How such processes operate he regarded as an empirical question, to be answered by looking at neuroanatomy – the engineering involved in brains. Darwinism, to Dennett, was the grand unifying principle that explains how the simplest of organisms developed into human beings who can theorise about the sorts of creatures we are. In Consciousness Explained (1991), he argued that the term “consciousness” merely describes “dispositions to behave” and the idea of the “self” was nothing more than a “narrative centre of gravity”. In Darwin’s Dangerous Idea (1995) he went further than any other philosopher or biologist in arguing that the whole of nature, including all individual human and social behaviour, is underpinned by a Darwinian “algorithm” – a single arithmetical, computational procedure. Borrowing Richard Dawkins’s notion of “memes” (“bytes” of transferable cultural ideas encompassing anything from a belief in God to an individual’s fashion tastes), Dennett argued that the Darwinian algorithm also explained, for example, the musical genius of JS Bach, whose brain “was exquisitely designed as a programme for composing music”. Dennett’s philosophy undercut any idea of teleology or “purposive” creation....

You forgot a -i in the exponent, Mordred. You are under arrest for violating unitarity. 🤣

The keyboard is laid out as a matrix of intersecting lines. Hitting the 'R' key closes a contact between the row and column lines and a value is sent , in hexadecimal format, to an 8 bit processor in the keyboard, which then serializes the ASCII code for 'R' and sends it, through a USB channel to the computer's USB decoder which converts it back to parallel binary data again, so it can be read by the CPU. No processing is to be done on this data, so it is placed in the common area of main memory ( RAM ) where it can also be accessed by the display processor. The display processor changes the binary data into a bit map and places it in the display buffer, adding any attributes that may be required for the specific windows display environment ( color/intensity ), and the display buffer is then serialized again to be output to a monitor, along an HDMI channel, to be 'drawn' on the LED/transistors of the screen matrix, one row at a time, until the whole screen is 'painted' at a refresh rate of 120 Hz, and the letter 'R' is displayed in that window. The Operating system, Win10 in this case, is responsible for setting aside the part of main memory that corresponds to the display buffer, and the particular subset that is the contents of that window. Do you really think you understand it better now ? Unless you learn the basics, you don't have a chance of understanding.

You only get to develop some intuition after you've done a bunch of examples. Do you mean, \[ \sum_{n=1}^{\infty}\frac{n^{2}}{2^{n}} \]? If that's the series you're referring to, the quotient is a good way to go. You generally use comparison when your general term is easily related to a well-known convergent of divergent series, like the geometric series, the harmonic, etc. The root criterion I would try when I have a function of n raised to a function of n. But it's not an easy subject in which you can give a fixed recipe. Code: \[ \sum_{n=1}^{\infty}\frac{n^{2}}{2^{n}} \]

I understand a computer must have so much hardware and software to make it "do something productive". Is the dictionary definition of computer concise and accurate enough for laymen to understand?

The promise is a small device, which can be connected to a smart phone, and register, identify, display graphically (spectrum and in intensity in time; also on Google Street Maps or Open Street Maps), radioactive substances, better (and cheaper!) than traditional Geiger-Müller counters. Here is their website. Here is a report of a physicist playing around with it. Some excerpts: I always like to measure things around me: where am I and how high (GPS), what is the temperature, moisture of the air, water temperature of the lake near my house, and on and on. Maybe I am a bit nerdy...

Escaping death from Nazis Germany. Making ground breaking discoveries and enjoying life seems like a blessed life. But back to Einstein as a Christian could living in the U.S. introduce him to Christian values. He wrote many essays that were more than just philosophies where he looked to improve society and his adopted American life. So the ingredients are there. I’m saying old Einstein is a different man than young Einstein. He lived through WWII. He also wrote a lot about the Jewish people. Maybe he writing the stuff and doesn’t know it shares many Christian values. And maybe while he is in the hospital a chaplain gets him saved. Easier to understand than relativity. Why all this speculation? There are enough articles from Einstein himself and several of his (serious) biographers to find out yourself. So either do that, or take my word for it (below), but stop speculating. Einstein used 'God' either as a playful metaphor ("God doesn't play dice" (well, he calls it 'The Old One'), or as the impersonal, Spinozian God. The latter has nothing to do with the Judean-Christian God. He explicitly has said that he does not believe in some personal God, who interferes with the universe, or even stronger cares about peoples (Jewish or Christian) or even stronger, about individuals.

Being offensive is no substitue for understanding physics. Your attitude is so obnoxious that I don’t see any point in pursuing this bullshit. I’m out.

Simple. There isn’t, I stated that, and I never claimed there was. I said there is shift in mass, which there is - the slugs move and the platform will also. You can only do this once, since your slugs do not return to their original position. (It’s not a cycle, or ”loop”) If they did, the position would revert to the original.

Chrysler is not Anglo-Saxon, you twit. I want the three minutes of my life back I spent reading this inane thread.

Zero. The platform will have moved up slightly, owing to the shift in the mass.

Thanks for the example, I get it now.

Thanks. I think that first paragraph of mine fell a bit short of the ABC I was after - accuracy, brevity and clarity - but I hope the meaning came through. Missed the time limit to edit or I'd have tried for more of the B and C. I do struggle with the B. I think stability is the optimum for the species including humans, that are around and doing well at the time. Not changing too much too quickly is much more "optimum" than any specific global average temperature especially if major and rapid climate changes are involved in getting there - but I note that (confirmed by the graphs provided) we were not in some cold part of natural cycles when we started burning fossil fuels in a big way, but were already at and just past peak of a natural warm period - so added warming doesn't take us back to a warmer "optimum" it takes us into territory not seen before, not unless looking at very long times ago, when conditions were too different to make any "better" or "worse" global climate comparisons. I'd call the argument a not actually relevant kind of wrong. The Holocence, the last 10,000 years or so, since the last Glacial Maximum had been unusually stable and there are good grounds to think that stability made it possible to get reliable food supplies from agriculture, enough for civilisations to arise and persist. Even the relatively small changes during that time saw rises and falls of civilisations. The warming isn't happening during a cold period, it is happening just after one of those peaks, one already different to what was happening before - warmer than prior peaks and persisting long after - (the red circling came with this graph, not mine, but finding one with the period before the Holocene wasn't so easy - not without log scaling that compresses the earlier times) - Whilst climate change will alter weather patterns many regions are that way because of geography that isn't going to change - changed intensities of what they already get appears more likely in most places rather than the wetter places turning dry or dry climates turning wet. eg Deserts with mountain ranges between them and oceans will mostly stay deserts, but the coastal sides can get wetter. Big atmospheric and ocean circulations get affected but not entirely overturned; lots of prevailing winds will still go the same directions, cross oceans and gather moisture - more water vapor than before. Where conditions suit that means more rain. For arid climates warmer air needs to have more water vapor content to reach saturation, in order to rain; they can get more rain from occasional extreme rain events that do reach further inland but outside those times get less. The impacts on people is kinda critical in this; for all that Environmentalists are concerned for natural ecosytems it is concern for the impacts on people, agriculture and infrastructure that drives most climate policy. All well and good if there is less desert and vegetation on average but the local impacts can still be overwhelming. I've heard it said that civilisation is just one famine away from collapse; some of the worst potential consequences aren't from the weather and climate and sea level, but from human mismanagement and responses to crisis, including corruption, blame shifting and conflict. If you live in a part of the world least affected by climate and weather impacts it could become the favored destination for a hundred million refugees; I don't see how any nation in a world that has become so interconnected and interdependent can isolate themselves from the impacts elsewhere.

The end might produce a few grams of actual matter in a brief burst of radiation. "Explode" makes it sound bigger than a wink. The vast majority of the original mass radiates away as massless particles, mostly photons and gravitons, neither of which is a building material for stars.

I did. If a person's gender is dependent upon their belief then the basis for my own gender identity may not be the same as theirs, so your attempt to suss out a "simple and scientific" basis for my own identity is a waste of time as it would not necessarily concede a rejection of a more complicated basis for anyone else's identity if the basis truly is arbitrary. See how confusing things become when we let people define words however they'd like?