Leaderboard

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.

It was a proposed theory by Hoagland that was rejected by the scientific community. However the term hyperdimensional computing theory is widely used. https://en.m.wikipedia.org/wiki/Richard_C._Hoagland#Hyperdimensional_physics However I have seen the occasional string theory textbook use the term. Even as part of the title of the book.

Or, to put studiot's physical science example another way, it's saying that the system is large enough that the small changes are outside of any experimental determination, while acknowledging that using "infinite" is unphysical.

This is a been a problem with your posts - you either don't read what was said, or comprehension isn't there. So you respond to something other than what was claimed Like here. I did not make a general claim about objects, I made a specific claim that the derrick is an object. That in no way can be (validly) extrapolated to mean that other systems can’t be comprised of multiple objects. So bringing up the fact that you can stack two books doesn't have any bearing on this. The can't form an action/reaction pair, since they don't satisfy the criteria for action/reaction pairs. Since you refuse to go look this up (and somehow you are arguing about Newton's third law without knowing this), I will once again list them. Make note, since I won't do it again. The criteria are: 1. Equal in magnitude 2. Opposite in direction 3. Act on different objects (they act on each other) 4. Same kind of force ALL criteria must be met. Normal force and gravity fail to meet 3 and 4, thus, any student of physics hoping to demonstrate understanding of the concept must realize that these are not an action/reaction pair. And, as I said, there are no reaction forces present, since a reaction force is one exerted BY the object. All of the forces in the diagram are exerted ON the object. The example in question was the bat and the ball. It doesn't apply to that pair of forces, since they are not an action/reaction pair. If they were identical they would be in the same direction, and identifying an action/reaction pair does not tell you whether or not there is a net force. See above. I can't believe you are this effing lazy. Newton's laws are fundamental to dynamics, too. Lots of problems are solved where F ≠ 0. You use the second law for them too. But it's pretty obvious you haven't studied more advanced physics if you have the misunderstandings you do. Not a strawman as you actually did it. Equilibrium is a conclusion from the second law. Action/reaction is the third law. They are different concepts. Did Dr. Czerski write that article? I didn't find her name on the first page, or on page 5 It really hasn't come into question when I talk about work, which is a tad more advanced than lecture 2 of physics 101. I realized that the problem is your interpretation of the website, and the issue is less of one of qualification as in clearly explaining the concepts. You can't ask a website for clarification. I didn't dismiss their claim. I inquired why YOU dismissing mine in favor of theirs. AFTER I pointed out that they did not actually back up your claim. (a can vs. must issue you have asserted didn't happen, and yet, there it is) If it's all fine then how about applying that information? The book and desk example mentioned gravity. Gravity in this kind of problem is exerted by the earth or some other (typically very large) mass. Thus, it can't be ignored. But, once again looking at the above list of criteria for action/reaction, we see that these force fail to fulfill all of the criteria. In that kind of problem you are worried about the moment of impact, though it would depend on the specific question. But in all the time the ball is in contact with the bat, the single FBD would apply, since those are the forces present. They may change magnitude, but that doesn't negate a FBD that is just identifying the forces Energy and momentum are not things that appear in the FBD. Forces only.

It's the other way round. When you reduce the volume (and increase the pressure) the temperature increases. Like when you pump up your bicycle tires: the pump can get very hot. And when you release the pressure, it gets colder. If you use an aerosol paint spray, the can will get very cold after a few minutes. This is how the heat pumps in refrigerators work. Maybe you are thinking of cooling a gas so it condenses to a (denser) liquid and then freezes to a (denser) solid? But in that case, the heat has to leave the gas and the liquid in order for it to cool down. The universe is a closed system, so there is nowhere for the heat to go, so the temperature, volume and pressure are related by the ideal gas laws.

Yanchinin looks like typo as the title of the pdf posted by @SergUpstart includes Janchilin V.L. Does this help..? https://www.google.co.uk/url?sa=t&source=web&rct=j&url=http://www.pirt.info/files/documents/proceedings_PIRT_2015.pdf&ved=2ahUKEwi7_aWduv7pAhVxsHEKHRFdBcoQFjAAegQIARAB&usg=AOvVaw3v6BAYpo9xPt503b_96TEq The name Janchilin only appears twice, most notably as Reference 21,on page 298. It may be worth a look...?

Spacetime curvature is not a single value, it's a rank-4 tensor; in the most general case, and taking into account the various index symmetries of that tensor, it has 20 functionally independent components. What this means is that every event, all observers agree on the overall tensor (meaning they agree on how its various components are related to one another), while at the same time arriving at different numerical values for each individual component. Yes, that is what global means. The Riemann tensor is generally covariant, and it's a tensor field, so it doesn't depend on any frames neither locally nor globally. Yes, it's components can be time dependent, but don't have to be. In this case some of them are. Yes. You can in some sense think of it as a global function on spacetime. Well, there is the difficulty of what 'at a given time' means in a global sense. What you can do though is define what is called a foliation - you can consider spacetime as an ordered set of 3-surfaces, with time being the ordering parameter. Each of these surfaces then can have a purely spatial curvature associated with it. This is called the ADM formalism of GR. Note that there are infinitely many ways to perform such a foliation, so this does not violate any principles of relativity since there is no preferred time ordering scheme. If you use the standard 4D formalism, then you use the Riemann tensor to define spacetime curvature, which is generally covariant across all of spacetime. If you use the above mentioned ADM formalism, then the spatial curvature of each hyperslice is described using a different quantity, which depends on the time ordering parameter. GR only places a constraint on local geometry, but it has nothing to say about global topology of your spacetime. So for example, the standard Schwarzschild metric equally well describes one multiply connected global spacetime, or two separate singly connected regions of spacetime. GR itself does not distinguish these, so the choice of topology needs to come from elsewhere. Yes. But they may not agree on times and distances, which are of course observer dependent. Yes, this is pretty much precisely the idea It's the various components of the tensor itself (up to 20 of them), and their relationships. You calculate the value of those components from the Christoffel symbols and their derivatives. Yes. Curvature in the time direction is nothing other than gravitational time dilation, and spatial curvature would manifest as gravitational tidal forces. No, there are no privileged vantage points. Any observer anywhere will calculate the same spacetime curvature, which is a tensor field extended throughout all of spacetime. Remember they use the same equations and the same gravitational sources, hence they must arrive at the same answer. Sometimes the choice of coordinate system can make a huge difference to how difficult the actual calculation is, so yes, in practical terms there may be differences. But the physics are always the same. No, it's not physically privileged, it's just that they were lucky enough to use a coordinate frame that makes the calculation easier. The physics are always the same for all observers.

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.

Can we please acknowledge that increased availability of guns in the US does add risk to officers during every police interaction, but that being black also adds risk to ones life during every police interaction, and that neither of these things justify the way police are treating suspects after they’re already in custody or the way they’re marching on and being violent with peaceful protesters exercising their constitutionally protected rights? Surely, we can move on now... Please don’t make me write another horrible run-on sentence one that

Your advocacy for police brutality suggest your statement here is unequivocally disingenuous. You've touted your belief in police brutality and, thereby, confirm you do believe it exist. It's hardly convincing that a person who holds such beliefs is in anyway sincerely or slightly interested in humans rights protection whatsoever. As decent human beings raised with a modicum of morals, they should have innately known to weigh "following training/orders" against the loss of common decency. "I was just following training/orders" is not an excuse for crimes committed while doing so.

A question about a sign convention that leads to a lot of confusion. This is not the only instance multiple sign conventions in Science. In this case it is a result of History. Thermodynamics was originally developed by physical scientists and engineers. They were concerned with making machines (steam engines) for the industrial revolution. Steam engines are heat engines. That is they thought in terms of input (heat in the form of fuel) and output (work). Both of these were thought of as 'naturally being' positive quantities. So they wrote their version of the Law of Conservation of Energy (The First Law of Thermodynamics) as ΔU = q - w. Chemists came to the scene from a different point of view. They wanted all forms of energy to have the same sign, whichever side of the conservation appearance they appeared so they could present the equation as a sum on both sides of the equation. So they wrote their equation as ΔU = q + w. By then it was also realised that, although all the terms are energies, there is a difference between ΔU , which is a state variable of the system, and q and w which are exchange variables of the energies crossing the system boundary. So they tidied up by stating that all energies crossing the boundary from the system to the surroundings are negative and all energies passing from the surroundings to the system are positive. Now they could add them up, move them about in equations and between equations in other parts of Science in a consistent manner. It is an improved system But it shows the importance of knowing the sign convention in use and the equations that go with it. This last remark also applies to other such instances of multiple conventions such as those in Electricity, Elasticity and elsewhere.

Presumably you are incredibly wealthy now, by exploiting this pattern. (If not, then I suspect your claimed correlation is bogus.)

IQ tests were originally devised for people with compromised cognitive ability, for whatever reason, to assess what they could do and not do, to assess their future needs. They were not intended to assess the able-minded person. At best, they test for particular cognitive skill sets and really only tell you how good a person is at doing the specific tests. Being 'clever' depends on the task at hand and one can only be labelled such for that specific range of tasks. Nobody, I can think of, is clever at everything.

Two mirrors is not infinite. Please don’t make me drag this out of you. Post your example, or step off