Leaderboard

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.

Strange: Yes, and they're all impeckable.

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).

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.

Title says it. Let's keep things sweet and brief enough unless you really think someone (me?) needs to get more learnt verbosely. Suffice to say in a word. New model to achieve some specific use/goals. Former form and some modifications at some level.

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.

michel123456: I don't know, and since the chicken doesn't know either, it doesn't have to account for the signal delay.

It is, see image (b). Image (c) is what the dice look like when you receive (at the same time) light that left the dice at different times and traveled different distances. Image (b) is what you see if you remove the differences due to delay of light. In fact, if you put points of light all over the dice and sync'd them to flash at a single moment in the observer's frame, what you see would look exactly like (b). This assumes persistence of vision or exposure time somewhat proportional to d2, since the light wouldn't all arrive at the same time. You could figure out so many mysteries if you learned SR. Do you mean the lengths between the dice? Those lengths are contracted, see (b). Here's a thought experiment to show that the spaces between objects are contracted the same as objects themselves: Consider the dice in their rest frame. Put an enclosure around each die, and connect them with sticks. In the moving frame, everything contracts, and the dice never leave the enclosures. The distance between the dice must contract the same as an object of the same length. Edit: After catching up to the rest of the conversation I see my explanation isn't necessary. I think that if you showed the dice say 1s apart (big dice) in a Newtonian frame I guess??? in (a), and showed them "at the same events" 1/gamma s apart in (b), it would look the same as it does now. If (b) showed them 1s apart in the new frame, they'd be spaced farther.

As usual, Ed Witten drew far-reaching conclusions, but missed the chicken completely.

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.

! Moderator Note You were told to give this a rest

Ed Witten: To get to the dimensions compactified on a Calabi-Yau manifold on the other side.

Weren't the Americans important in brokering the Good Friday agreement? If so it seems they can reasonably claim to have a stake in the matter.

OK. Ken Wilson : When you subtract the infinite virtual chickens that went everywhere, you're left with the renormalized chicken across the road. and Why does a hamburger have less energy than a steak ? Because it's in its ground state.

Feynman: The chicken tried everything it could. It only looks like one chicken doing one thing because he fell down a stationary-phase path.

Erwin Schrödinger: My chicken is dead and alive; it sneaked across the busy road while I was looking the other way.

Why did the chicken cross the basketball court? He heard the referee was blowing fouls.

Gifts of silver and gold will vir- ginity tend to put an end to. The tortithe and rabbit rathed theee timeth thith month. The rabbit won twithe and the torithe onthe. Started choking, turning purple, A hardy slap and one good burp'll put you to rights. Quoted from memory. Credit: James Hogan. There was one with orange as well, but it was really reaching, and I don't remember it.

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.

I'm voting for appallingly cynical. Just because you feel that way doesn't mean the rest of us do.

I don't see what the problem is. D Trump was right. Large portions of the American population HAVE developed 'herd mentality'.

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.

Lol, I do that every day That’s one of the big positives about being just an amateur - there’s no obligation, pressure or expectation on us to deliver anything, so we are free to pursue what we like and find beautiful. I know for myself that I would not have performed very well in the pressurised environment of professional academia. I used to have a lot of regrets about not choosing that as a career path, but now I’m almost glad I didn’t.

Einstein didn't 'guess' In fact he was one of the founders of the quantum theory. (1905) This was of course long before a probabilistic explanation was suggested. In any event the probabilistic wave theory has since been found inadequate/incomplete, though still able to provide calculation and prediction for some phenomena. I have underlined the appropriate words. So he was actually correct. https://blogs.scientificamerican.com/observations/einstein-and-the-quantum/

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

I do have a picture of Hell for scientists. It consists of spending all eternity proving every silliest craziest hallucinatory idea wrong. And it's here. I don't know about Heaven, but Hell is nothing like what I expected it to be.

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/

Everyone feels that way really. It's just that most people don't like to display it. That's understandable. And not at all a bad thing. What would happen to families, and society, and civilisation, if we all displayed the truth to each other all the time. We'd be mere inconsiderate animals. The uniqueness of humans is precisely our capacity to lie about our true feelings, in order not to hurt others.

I don't remember that when I was a child, I got taught any lessons at all from my parents about caring and getting along with siblings, and other people. I was horrid to my younger sister. I had to figure out the correct operating principles for myself, in later life. This was accomplished by reading loads of books. Mostly science fiction books. Especially Asimov's "Foundation" series, which reveal invaluable lessons about human behaviour. I could go on to explain further. But who cares? This forum is about hard Science, not fiction! I never go into bars, as they tend to be full of drunks who start fights.

Is it - a Liberal?