michel123456

Make war illegal.

So there is a net force on the stroller that dictates its motion.

i don't understand your previous post. This is what i understand: When Ruth is at a distance the force she exerts on the stroller is zero and is equal to the force the stroller exerts upon Ruth: that is zero. When Ruth pushes a little bit on the stroller, the force Ruth exerts on the stroller is the same with the force the stroller exerts upon Ruth. When Ruth pushes more, again the 2 forces are equal and in opposite direction. IOW the forces are always equal and in opposite direction. At some time, the force Ruth exerts on the stroller is enough to put the stroller in motion. What is that? Does Ruth exerts an external force? the change in motion means acceleration, no?

Most generally i disagree. You wrote: In my view motion is not a change of state of matter/energy. Motion is a way to conserve energy. What you describe is change of motion aka acceleration.

If the 2 forces are equal and in opposite direction, what is that makes the stroller move in one direction and not the other?

Ooh that brings me back many years ago. Thank you Etgar. If the force is equal then we have equilibrium, don't we?

Exactly. Object's spacetime coordinates should have nothing to do with mines. What (i am arguing) is happening is that I am scanning only the d=ct part of the universe. If the universe is traveling at the same pace that I do, I continuously scan the same objects.

I know it is hard to swallow. Please take some time rethinking the picture. I am at t=0 observing a universe that spread along the diagonal d=ct. After 1 year i am at t=1 observing the same universe that spread along the diagonal d=ct and so on at t=2 again the same universe collated upon d=ct The observable objects of the observed universe travel through time on a parallel path to me. I observe constantly the same universe. The superposition of all diagrams t=0, t=1, t=2 fill the entire spacetime diagram. Till here we must have an agreement. But At any time, between t=0 and t=1, what are we traveling into ? _The answer is; we are traveling in spacetime. IOW we are traveling in a supposedly "empty" spacetime where there is "nothing' else than d=ct observable objects. (you seemed to agree on this) Now, i am arguing that one can fill the whole diagram with 'other' objects that will follow a parallel path to us but with a gap in time. I am arguing that those "other" objects would be unobservable. Even not from a picture from T=minus 1. Because at T=minus1 we were observing objects on the d=ct diagonal. I am offering you a new denser Universe.

Great pictures. I live with that in Autocad on an everyday basis. No need for fractals. Zoom and Scale commands have exactly the same effect on my display screen. Except that zoom has no effect on the objects while scale has an effect: scale changes the absolute dimensions, zoom not. But still, if I change the metric in CAD, by setting for example that meters become millimeters, then again scale may have no effect. IOW if I set the change in metric equal to the scale factor, zoom & scale have exactly the same effect. As for the rest of your post, I suppose I should agree. My position is that distance is the exact same thing as time (with the opposite sign). That is not much different than yours. But that's all speculation. --------------------------------------------------------- (bolded mine-great post!) Yes. A similar remark is made by Brian Green's "Elegant Universe". i'll dig to find the exact quote. --------------- My edition is in modern Greek language. the remark is in the beginning of chapter 13. Found this from here on the web This the quote: (...)Black Holes and Elementary Particles At first sight it's hard to imagine any two things more radically different than black holes and elementary particles. We usually picture black holes as the most gargantuan of heavenly bodies, whereas elementary particles are the most minute specks of matter. But the research of a number of physicists during the late 1960s and early 1970s, including Demetrios Christodoulou, Werner Israel, Richard Price, Brandon Carter, Roy Kerr, David Robinson, Hawking, and Penrose, showed that black holes and elementary particles are perhaps not as different as one might think. These physicists found increasingly persuasive evidence for what John Wheeler has summarized by the statement "black holes have no hair." By this, Wheeler meant that except for a small number of distinguishing features, all black holes appear to be alike. The distinguishing features? One, of course, is the black hole's mass. What are the others? Research has revealed that they are the electric and certain other force charges a black hole can carry, as well as the rate at which it spins. And that's it. Any two black holes with the same mass, force charges, and spin are completely identical. Black holes do not have fancy "hairdos"—that is, other intrinsic traits —that distinguish one from another. This should ring a loud bell. Recall that it is precisely such properties—mass, force charges, and spin—that distinguish one elementary particle from another. The similarity of the defining traits has led a number of physicists over the years to the strange speculation that black holes might actually be gigantic elementary particles. In fact, according to Einstein's theory, there is no minimum mass for a black hole. If we crush a chunk of matter of any mass to a small enough size, a straightforward application of general relativity shows that it will become a black hole. (The lighter the mass, the smaller we must crush it.) And so, we can imagine a thought experiment in which we start with ever-lighter blobs of matter, crush them into ever-smaller black holes, and compare the properties of the resulting black holes with the properties of elementary particles. Wheeler's no-hair statement leads us to conclude that for small enough masses the black holes we form in this manner will look very much like elementary particles. Both will look like tiny bundles characterized completely by their mass, force charges, and spin. But there is a catch. Astrophysical black holes, with (...) B.Greene the Elegant Universe Chapter 13.

Thank you. And if (IF) they were objects that filled spacetime, instead of being empty, those objects would be unobservable.

--------------------- In other words, we consider that at some definite time, spacetime is empty except for that we can observe.

nothing.

Please elaborate. i suppose many members may help if they understand clearly what's all about. In school what grade? What do you mean by 'designer materials'"? Any info welcome.

E.T. intelligence will look like nice guys with flowers in their hair giving us welcome gifts with a smile. Most probably we will exterminate them. After some years we will dispute their remains between the British Museum, the Louvres and the American Museum Of Natural History. After some more centuries, the few survivors ET will ask for their remains to go back home. We will refuse that demand of course.

By measuring some effect first and the cause after..

O.K. that gives you a diagonal. And at this same t=o, what can you plot on the rest of the diagram ?

At one time (say t=00), you pin in a spacetime diagram all the observable objects around you, what do you obtain?

I agree. Although I am not expecting the next Einstein. But some nice idea, why not? On the topic: Yes of course 2 particles is a spectacular improvement compared to a bunch of elementary particles. I wish all the best to this speculation. But anyway the question will remain: what are those 2 particles made of ? the question has no end. Which makes me think that we have it completely wrong in our quest of the elementary particle. I don't know the answer, but we must be wrong.

Insects are used because: 1. they are frightening 2. they are easy to make in virtual reality.

And I remember somewhere having read a theory that said that first humans were merely scavengers. Which explains why we like some kind of decadent food made from fermentation, like cheese, beer, bread, french & italians salamis, patés and other faisanderies. This will derail the thread completely, but I have another point of vue. A naked human with small teeths, weak nails no fur, could not survive 24h anywhere on the planet witouth intelligence..

i had thought that intelligence was a random feature. IMHO we are intelligent by chance or by error.

Welcome. I am an architect, so I need doors & food. Few here are physicists so always beware the answers you get. IMHO the multiverse idea is a misinterpretation. Some physicists have argued that for a photon to travel in straight line from point A to B, in fact the photon travel all possible paths throughout the entire Universe, (see Fermat principle & quantum electrodynamics here) but that all those incredibly strange paths cancel out so that the only remaining one is the straight one. the argument states that all those paths are not only mathematical concepts but that theses are really paths happening in reality. From this statement some other people have created the concept that for each event happening in our universe, all other possibilities must also happen 'somewhere else" in another universe. The flaw IMHO is that in the photon concept, the entire set of other paths are not exactly 'possibilities", they are "impossibilities" because they cancel out (and they aresupposedly part of our universe). That's the reason why they don't really happen. IOWwhat we call the "other possibilities" are not "possibilities" because if they were happening, they would cancel and the universe in which they are happening would collapse. In order to get a "parallel universe" in which there is a another Chef-carpenter, this other universe must work out. I am not a partisan of the multiverse,

I never thought of intelligence that way. Where did you get that from ? ----------------------- one must also consider the difference between intelligent and technologically developped. Most probably Neanderthals were as intelligents as we are (maybe more) but upon all evidences developped no advanced technology. Dolphins are very intelligent animals but have developped no technology. They are many examples.

Correct. i should have stated: if there are objects that fill the entire rest of the diagram, these objects are directly unobservable.