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Looking over the thread, my opinion is that it is far too complicated, with too many aspects you haven't figured out yet, but which you would need to describe all the things you're trying to (eg. relativity of time, relativity of distance). Instead of looking at the things that don't make sense to you, why not start with at least one thing you do understand, and build off of that? I suggest the following: 1) Start with a simpler scenario. Use just 2 observers at first. The basic twin paradox is good because it is concrete; the twins start and end at the same place and can see each other's immediate age without worrying about synchronizing with a distant clock. Or if you prefer it, both observers moving inertially and setting a start event using a light signal from one to the other, is also simple enough. You could choose, but stick to one. You can add more to it later, to figure out other things. 2) Understand it first from at least ONE inertial frame of reference only, to start. Don't start trying to figure what a second observer measures, if you can't made sense of what the first observer does. 3) Write out the equations as you go. I don't see how you could understand how the numbers add up without calculating them. I bet that SR could be figured out from scratch by amateurs using just the 2 postulates, some geometry, and the timing of light signals, if you're interested... But you really have to understand more of the basics to figure out what you're trying to in this thread.

Does the forum software here support the ability to number posts within a thread? If so, wouldn’t it make sense to turn that function on? More than once now have I had to refer back to what someone said earlier on a thread, in a way that just can’t be done easily using the quote function. There are just situations where it is easier to simply refer to a post number (“You made this claim in post #…”). Thoughts?

Find the URL under the text “posted 28 minutes ago” at the top of all posts and copy/paste it (whatever time interval has passed since submission). Here’s a link to your post I just quoted. https://www.scienceforums.net/topic/128812-numbering-posts/?do=findComment&comment=1230067

Actually, gravity doesn't create g-forces at all. None that can be felt, anyway. What we experience as the "force of gravity" is really the pressure force of the floor or whatever other object is supporting us. Taking the word "suddenly" literally, we would all be killed by the infinite force required to accelerate us instantaneously. Even a sharp gravitational pulse would rip us and Earth apart by accelerating some parts more than others. I'll assume you're asking why we don't feel the centripetal force of orbiting the sun at high speed. Speed itself doesn't require any force as long as it's constant and the motion is in a straight line. In Newtonian physics (i.e. old-fashioned Physics 101), the reason we don't directly feel the effects of gravity is that inertial mass is equal to gravitational mass. Inertial mass is the m in Isaac Newton's 2nd law, [math]F=ma[/math], and gravitational mass is the mass in his law of gravity, [math]\displaystyle{F_g = \frac{GmM}{r^2}}[/math]. They cancel out: If gravity is the only force acting on an object, then [math]\displaystyle{ma = \frac{GmM}{r^2}}[/math], so the object's acceleration is [math]\displaystyle{a = \frac{GM}{r^2}}[/math]. Gravity affects every molecule in your body exactly the same way, so your nerves don't sense any change in your body's configuration. This is why Albert Einstein was able to model gravity as the curvature of spacetime in his general theory of relativity. In that theory, gravity isn't even a force. It's just the curvature of spacetime, and objects with no (other) forces on them simply travel along "straight" lines. Not literally straight lines, because space itself is curved, but along curves called "geodesics", which are as straight as any path can be in the curved space.

Few questions based on the analogy with light/sound waves. I suppose most cannot be answered strictly, but at least give me your hunches. 1. Should I expect that gravitational waves may reflect when they hit some sort 'wall'? Can such wall exist? Can we have phase-change and non-phase-change reflections? Can you suggest a 'wall' (either active or passive) that causes phase-change or non-phase-change reflection of gravitational wave? 2. I suppose gravitational waves can interfere? Is this a linear or non-linear process? 3. Can we imagine a standing gravitational wave? Can we imagine resonant cavities for gravitational waves (possibly allowing amplification)? 4. If we have multiple controlled sources of gravitational waves that act near-coherently, can we employ beam-forming - thus making a directional source of gravitational wave? 5. If directional gravitational antennas are possible, will such an antenna experience an impulse to the opposite side of the main gravitational lobe?

We all have our own preferences, myself included. Some of these are hetero-normative and accepted by culture, others are not hetero-normative and thus get shunned by culture... at least until the holdouts eventually die off and go away. Part of where I'm struggling here, however, is with the examples being used. In everyone's attempt to make themselves better understood, you're choosing very prejudicial comparisons. I mean, don't me wrong. If all you're saying is, "yeah, that's just not my cuppa tea," then super! Good on ya! I couldn't care less, and guess what? It's not my cuppa tea, either!! But that's NOT what is being said. Instead, we're seeing non-hetero sexual acts between a same sex couple getting compared to: - Pissing on someones face - Shitting on a salad and being asked to eat it - Shoving inanimate objects into ones asshole - Spitting, coughing without covering, picking ones nose, and scratching ones balls - Mental illness, disabled, defective minds, nasty... all right here just in this ONE thread! We've got scores of them here all doing the same thing... Now magnify that across all interactions homosexuals are having every single day of their lives... all just to be accepted for who they are. And you know what chaps my ass even more? You DON'T feel this way about "homosexuality." No... You've probably beaten your baloney pony more than once at the thought of two girls being intimate together, because that's about POWER. It's only when two dudes do to each other some of the exact same things dudes often do with dudettes (butt sex and blow jobs are hardly limited to homosexuals, my friends)... it's only THEN that you suddenly magically have a "disgust" problem. It's not the act you find distasteful since it's fine when its opposite sex couples engage in it. It's the same sex couple, specifically the males, that you just can't bring yourselves to accept. I don't care if you get hung up on the word prejudiced or if it causes you to feel some cognitive dissonance with the "good person" narrative you have in your self-identity. It IS prejudiced, especially since it's NOT an amygdala-level olfactory response like the way you feel drinking coconut water being described here. It's learned, and thus can be unlearned. Extinguished like a bad smoking habit.

There would not be photons either, because electro-magnetic wave needs 3D. Without photons, charged particles would not interact. Thus, there will be nothing to hold atoms intact. There would not be objects, just a chaos.

What is your definition of "judging"? I've always felt "judging" required a conscious decision, whereas "distaste" is not necessarily arrived at with forethought. IOW, "distaste of a sex act" doesn't feel like a "judgement" to me.

Actually I think that change served a deliberate purpose. Given that the model of the atom changed radically from the Rutherford-Bohr model to the modern (Schrödinger?) model, the word "orbit" became objectively wrong, so orbital was chosen instead, to signify the new model. P.S. Another name change in chemistry that bamboozled me briefly is from ESR, which I remember from university, to EPR, which is virtually the same thing. I suppose there is in principle a change, in that EPR implies one thinks in terms of the more general J, rather than S.

There is a function available by clicking "more options" for a post (may be different between devices and browsers) : This windows appear and the direct link is presented: Here is the result when using your post above: edit: x-post with @iNow

Difficult to answer without knowing where you are or what your level of maths is. Note that some 'modern physics' books assume you know classical physics quite well so are best avoided unless you have this grounding. Some deserve the title/description Physics for the Modern World instead. I will only mention this type. Some good american authors are Arthur Beiser He has written several versions - try for Concepts of Modern Physics. Robert Mills An introduction to Contemporary Physics Exactly what it says on the tin. An introduction with lots of background explanation/ information. Mills has an exceptionally clear way with words. Leonard Susskind and Art Friedman Offer a three volume set in Penguin with the aim of 'The minimum you need to know for the subject@ Quite a bit harder than the first two. You need better maths for these. UK authors You will never go wrong with almost any edition of Nelkon and Parker Ordinary level Physics Advance level Physics If you will be looking at UK stuff you might also like to look at 'Engineering Science'. UK use to offer more practical, less mathematical, and wider aspect courses in what amounted to a combination of basic Physics and Materials Science, much of which has been dropped from 'modern physics' courses. They offer a quck and easy way to get many essential facts quickly.

Yes, when there is no other influence, things are in freefall. Freefall is a curvilinear motion (geodesic), with the degree of curvature dictated by the mass-energy of the larger object. The two attracted objects actually affect each other but it's simpler that way. If you are freefalling you feel no acceleration i.e. no change in speed or direction... that's gravity. If either of those changes, speed or direction - which we call velocity because it has those two components - you are no longer under freefall and one experiences a resistance in ourpath of motion. That's when we think we feel gravity.

Mass-energy curves spacetime, which causes freefall in objects in free space. Force of gravity is the resistance one feels when our own curved freefall path (geodesic) is inhibited by a more massive object we are attached to i.e. Earth. Spacetime is the 3 dimensions plus time. It is a mathematically-described geometric platform with spatial and temporal co-ordinates scientists use to describe and track events* in space and time. *From Wiki: In physics, and in particular relativity, an event is the instantaneous physical situation or occurrence associated with a point in spacetime (that is, a specific place and time). For example, a glass breaking on the floor is an event; it occurs at a unique place and a unique time.

When light propagates through a material, it travels slower than the vacuum speed, c. This is a change in the phase velocity of the light and is manifested in physical effects such as refraction. This reduction in speed is quantified by the ratio between c and the phase velocity.

I’m sure I’ll see him at the Iowa State Fair this summer glad handing and flipping pork chops on the grill. In fact, Nikki Haley is already gonna be just up the road from me this coming Monday… VP Pence and Mike Pompeo (who shockingly also both have books) surely aren’t far behind, either.

You can like or dislike anything you want. Quit being so melodramatic. The point is we can tell you how certain of your dislikes are outdated and need to be softened, if not abandoned entirely. People used to dislike white women being with black men (some people still do). Some used to dislike Jews (again, some people still do). Some people used to dislike letting Italians and Irish into the country. Some disliked the Polish. Dislike of homosexuals and transsexuals and acceptance of both is just the latest in a long string of human hatreds and small minded ignorance. Some dislikes just need to go away and die. Some of us dislike how long that seems to be taking and are maybe trying to help accelerate the pace.

The opening question was "According to mainstream physics: Is heat "destroyed" in a heat engine?". Do you want the answer as stated by current mainstream physics of today? Or do you want the answer as it was in mainstream physics at some specific time in the past? (Or other alternative?). Since many historical references are brought up, can you clarify?

Doesn't seem weird to me. I find people chewing gum distasteful. I don't think it's wrong or that they shouldn't enjoy. That something may not appeal to my own aesthetics is not a judgment on its moral legitimacy. I think that's where many straight males are, re gay sex. You can find some activity distasteful (golden showers, anyone?) without minding in the least that others enjoy it.

The details are actually quite complicated, but I can start simple (and my apologies if it is too trivial) and maybe start with comments on some of the trickier parts. As you mentioned, the terms LDL and HDL do not refer to the cholesterol itself. Rather, cholesterol is transported packaged by lipoproteins, the mentioned high-density lipoproteins (HDL) and low-density lipoproteins (LDL). In addition there are also very low density lipoproteins (VLDL) and intermediate density lipoproteins (IDL). The measurements therefore refer to the fraction of cholesterol associated with particles of specific density that circulate in the bloodstream. To complicate matters on this level a bit, there are slightly different assays that measure the fraction of LDL in different ways (often indirectly, e.g. using the Friedewald equation, whereas direct methods often also measured IDL and VLDL). There is some data suggesting that using ApoB (which only not associated with HDL) could be a better biomarker for cardiovascular health, but that is under discussion, too. But one way I think about VLDL- IDL-LDL is that they are different maturation steps where the very large VLDL are reduced in size and then can enter the intima. Now, originally it was believed that LDL is a transport vehicle to move cholesterol to peripheral tissue and organs and HDL moves surplus cholesterol back to the liver. In part, the idea is then that very high LDL-cholesterol leads to deposits that can cause arteriosclerosis, for example. However, when trying to look at associated mechanisms, things get complicated pretty fast. For example, it was found that the vast majority of cells actually have an active lipid metabolism and most cholesterol are produced where they are used and are not necessarily delivered via LDL. Then, there is the issue that a lot of LDL cholesterol is derived from HDL and a lot of them is taken up by LDL-receptors in the liver. I.e. of the LDL is actually directed to, not away from the liver, making it questionable whether delivery to the periphery is really the main function of LDL. Likewise, HDL has been known to be critical for cholesterol efflux capacity (removing cholesterol from macrophages and transport to liver), but now studies suggest that LDL amplifies these efforts by HDL pathways. So taken together, the classic dichotomy of LDL vs HDL (cholesterol) has become rather questionable but we do not have a fully articulated model yet that can be used for better health prediction. Edit: I should add that my expertise is mostly limited to biomarker analysis, and not the clinical aspects, so it is therefore biased a bit more on the molecular/analytical side and may not reflect clinical standards. Therefore none of it should be considered medical advice of any sorts.

Psychology is categorically obscure, but reducing psychology to brain imaging is like reducing physics or biology to telescopy or microscopy. Quantifying the content of communication should matter. Neuroscientists, like all scientists, rely on the reliability of a basic willingness to communicate. Psychologists and anthropologists quantify not only communication, but communication patterns and ability, and the emerging social behavior and cultural activities. You can ignore good communication when it works and superfluous communication when it's insubstantial, but don't forget that bad communication will waste resources, time, cognition, public trust, and everybody's credibility. Of course, that might seem insubstantial to a narrow-minded person awaiting a paycheck. How about any logical framework of mental representation, adaptive behavior, or verbal communication that mutually reinforces the data analysese?

Not new neurons, but neurons that already remember relationships between the network's inputs in existing memories (e.g. visual characteristics of complete images). They will activate other neurons that remember other aspects of the same memories (e.g. various images that share properties represented by that neuron, testing to see what other properties the new perception shares with those memories). (a) The state of each neuron is represented by a dimension in the net's (very high-dimensional) phase space, (b) each memory corresponds to a point in that space, and (c) the net is designed in such a way that its state will approach (i.e. be "attracted" by) the point that corresponds to a memory if a new perception puts the net in a state that's close enough to that point, i.e. within the point's "basin of attraction". An initial state of the network is the point in phase space, i.e. the collection of individual neural states, that a new perception (e.g. image) puts the net's neurons into. This is the flow map of how the net's state can go from various initial states, through other intermediate states, to the state for the specified memory during the net's recognition operation. This is the set of states that will eventually lead to the point for the memory. The endpoint (attractor) is the "lowest-energy" point in the basin, and the boundary of the basin is a "ridge" that separates the basin from other basins. So you can think of the net's phase space as a hilly terrain where each valley corresponds to a memory.