Pete

Its proof I'm looking for. Not assertions. That's pretty vauge. I don't see how that will prove anything. Please be more specific. Pete

Thanks for chiming in swansont! That's what I'm trying to determine, i.e. what does quantum mechanics predict when this is done? Let me clarify - I'm asking how to use quantum theory to predict if the particles are still entangled after the first measurement is done. I don't exactly have a lab to do the experiments. To be more precise - Consider a two particle system in a spin-singlet state. Suppose one measures the z-component of spin of particle 1 to be "up." Particle 1 would then be left in the state |(1):z;+> (The (1)" means is particle "1", the "z" means that the basis is the basis corresponding to spin measured relative to the z-axis and "+" denotes the spin up state). We know that a subsequent measurement of the z-component of spin of particle 2 will be "down." I.e. we would find particle 2 in the state |(2):z;->. Suppose particle 1 is found in the state |(1):z;+>. Then quantum theory states that |(1):z;+> can be expressed as the superposition of the the base kets |(1):x;+> and |(1): x;->. If the x-component of the spin of particle 1 is measure and the result is "+" then particle 1 will be in the |(1):x;+> eigenstate. Here's the big question - Does does quantum theory predict that the result will be the particle 2 in the state |(2):x;-> when the x-component of spin of particle 2 is measured? If so/not then how can it be proven using quantum mechanics? Pete

There is a new book out called Einstein's Mistakes, by Hans C. Ohanian. Ohanian is a really good relativist and an excellant textbook author. I just got a copy of this book. So far is prettty good. Its nice to have a good source like this so one can have a ready reference to Einstein's mistakes, especially since so many people like to think they've proven Einstein wrong. At least this book gives an authoritative collection of his real mistakes and not the claims of his mistakes. Good reading so far. Pete

Does anyone know how to prove whether or not two particles in s spin-singlet state of a spin 1/2-system remain in a tangled state after a measurement of the spin of one of the particles is made? Thanks Pete

As I recall he used arguements from thermodynamics. If you do a search under "Einstein's A and B coefficients," "stimulated emission" and thermodynamics then you might find what you're looking for. If not then let me know and I'll did through the texts that I have and see if I can find a good explanation/derivation. If you'd like I can then scan the pages in and upload it onto my website where you can download them for your reading pleasure. However swansont's link seems pretty good. Excellant link swansont!!

The photograph you have provided shows a bar graph. Each bar corresponds to a representative frequency in a given frequency range. The height of the bar usually represents the decible level of the sound of the signals in that frequency range. Pete

I think that some people use those terms interchangably. I prefer the term torque myself. Pete

The term trauma suggests that there is an injury involed, either physical or psychological. I don't see the need for anything which could cause trauma. Very well put! Pete

Since when did I said it did? You seem to think that parents that would spank a kid always hit them for punishment. If so then I don't see anyone here making that assumption. What does that have to do with spanking a child??? There is a huge difference between violence/abuse and spanking. What if the speed of light really did depend on the observer's frame of reference. If ifs and buts were candy and nuts we'd all have a wonderful Christmas. Let me know when someone proves it then we'll talk. Until then let me ask you this - What if you were to discover that raising a child who was never spanked led' date=' in general, to adults who are not decent people, crime prone and more susceptable to drug addiction? What if you learned that children who weren't spanked after they struck their parents more often than not ended up in jail in the adult life? As I said, we can speculate all we want. My father never beat me and I actually have no memory of him ever hitting me. I behaved because I knew he wouldn't take crap from me. When he raised his voice I listened! If I knew that he was actually a paper tiger then I'd have probably paid less attention to him. My grandmother did smack me quite often with that damn fly swatter though. But I never grew up to be violent by any means whatsoever. In fact I'm quite a pacifist. I even doubt that I'd even spank my own child. But I'll be damned that I'd want the government tell me if it was right or wrong to do so. After all I'm not parent and I'd have to actually be a parent and have a kid before I'd see if it was neccesary. And even then I might never have a kid who would need it either. I now understand my grandmother using that fly swatter though. I hear I was a bit of a helion when I was a tike. There is a lot of exageration in this thread. There seems to be no distinguishing between beating a child and merely spanking them. I was spanked. I had friends that were spanked. None of us grew up to be violent or had any seething rage. But if I were beaten that would be a very different story. That's not a voice. That's a guess made before I ever knew what its like to have kids, never mind having a kid who was a real trouble maker. Come on people! Let us be more clear on the difference between merely spanking a child versus beating the crap out them huh? Sheesh! Pete

Thank you all for the suggestions. Much appreciated. Pete

What effects do you think yelling has on a kid? Do you believe that there are no occasions in which it could cause psychological damage? Parents yelling at each other can certainly cause psychological damage to their children but we can't exactly arrest parents for it, nor should we. If you tried to ground an adult you'd go to jail for false imprisonment. Sending a child to be without supper cold be viewed by some as child abuse too. No. It is not screamingly obvious at all. How could one universally judge parents when children's behaviour is so radically different between individuals? And its not as if a parent who would spank their child would ever need to do so, or need to do so more than a few times, after which the fear of it would make them think twice. If it is a matter of choosing between smacking them on the behind or knowing they're heading to being drug addicts then I'd take the belt out myself it I needed to. But I'd sure hate to do it. If I ever had to spank my kid (if I had one) then I'd wager that a little piece of me would die. But if I believed with all my soul that my kid's life would be better for it then I'd pay that price. I sincerely doubt it would ever be a problem though. And I doubt that spanking a child would be neccesary in the long run since a kid would get the point across fairly quick. If it didn't work then I myself would cease doing it. Thank God I don't have kids! But I know that I'd never like a law banning parents from "spanking" their kid. Pete

I don't think that there is any question about this subject. It is wrong to beat a kid no matter what. That doesn't mean that its wrong to hit a kid though. Hitting and beating are very different things. By "hitting" I'm talking about a cuff upside the head or a smack on the rump with a belt, not so hard as to leave a bruise though. The mere comment "Wait until your father gets home" was enough to set me straight in a hearbeat because I knew he had no reservation about hitting me with the belt. It is the fear of the belt that does the work. But if you never use it then its a paper tiger. I also remember comming home at 4:00am one morning. My mom gave me a good cuff upside the head. I never did that again! As far as beating your kids would cause them to be abusive later in life - Please note the difference between beating and corporal punishment. They are not the same thing. My parents never beat me, never! But I was scared to death whey my grandmother took out the fly swatter. She used that to give be a smack on the butt. Ouch! I don't consider that a beating though. I did learn how to hide those fly swatters pretty good though. If that was sufficient then there'd be no need for hitting a kid. More often than not I'm sure that works. But there are kids for which nothing like that will work. Suppose you give a kid a "time out". That only means that they're supposed to sit still and be quite for a certain period of time. That doesn't mean that they will. It may be next to impossible to get them to do that. Depending on the child, grounding them only means that they will sneak out. In many cases all this does it to make the kid more cautious, i.e. Next time I won't get caught! A parent can do everything exactly right and yet their one kid may still be disrespectful. It can simply be genetic, a part of his personal make up. It doesn't always mean that they were raised wrong. Ever hear of the proverbial black sheep of the family? This usually refers to one child for which the parenting, which worked fine on all the other kids, didn't work on that one kid. This isn't always the parents fault. Some people are just born that way. I recall a friends kid who wouldn't listen to anything their parents said. They would always say Don't make me come over there! or I'm warning you one last time! but then they'd never follow up. I'm sure that a lot of the time they kid may be bipolar or have ADHD or ADD. When I was a kid they didn't know anything about that kind of stuff. Pete

Cool! I thought the series had ended! When does the next second part of the 4th season start? Pete

I watched nearly the entire series Battlestar Galactica but I must have missed the episode where the fifth Cylon was revealed. Does anyone know who it turned out to be? Pete

I created a web site for just such a purpose. Its located here http://www.geocities.com/physics_world/sr/sr.htm Take a look and let me know if it helps. Let me know if you have any questions/comments. Thanks. Pete

There is the possibility of other universes which are spatially disconnected to our own. Pete

In responding to a question about relativity one must ask about what is actually measuring. Even traveling a slow speeds in an atmosphere there is a doppler effect which makes sounds sound higher/lower and thus voices speaking faster/slower. This is caused by the increasing/decreasing distance between source and observer. If the source is moving in a circle there is no doppler effect. However there will still be an additional relativistic effect in each case due to time actually slowing down with the relative speed of source and observer. By that its meant that processes which occur in one frame run at different rates as measured from a moving frame. If the observer is at rest and a source remains at a fixed distance then the time in hte moving frame will be observed to be running slower compared to the time in the stationary frame. Thus even though there is zero doppler effect there is still a time dilation effect. In this case the "sound" waves will still result in the person's speach sounding slower, in this case because they are actually speaking slower. Pete ps - I've ingored things like what happens when a body moves through air at relativistic speeds.

Excellant point. I neglected to mention that the vpoice would sound slow if the ship was moving away and sound higher if it was higher if the ship was getting closer. It would sound slower if the distance remained constant such as if the ship was moving near c in a circle with the earth at the center of the circle. Pete

Nope. I meant to say that the Earth player is synchronized with the ship player as measured in the Earth frame. Of course this means that the players are not snychronized in the ship frame. And it also possible that, according to the ship obervers, the ship will start to recieve the message before it is sent. That's the problem with instantaneous communication in relativity! Pete

Your question as stated could have been rephrased in such a way so as to provide you with the response that you were seeking. All we have to do is cheat. Here's how I'd do it: Suppose we first make a recording of the vocal message on a digital recording device. The recording is duplicated. One copy of the message is left on the earth and the other is placed on player which is comoving with the ship. At a later date the ship is moving relative to the earth and at t = 0 as measured in frame S, the rest frame of the earth, the recording starts to play on the earth and the ship. The player on the ship is synchronized with the player on the ship, as measured in S, and each player runs at the same rate as measured in S. This exactly duplicates what would happen if the signal was relayed instantaneously. The answer to your question is that the voice sounds slower. Pete

It may seem trivial to mention this but it is imporant to understand if you want to understand thermal physics (so don't get the impression that I'm trying to be nitpicky). Heat is defined as the any spontaneous slow of energy from one object to another, caused by a difference in temperature between two objects. The temperature of water increases in this case because work is done on it. The first law of thermodynamics states [math]\Delta U = Q + W[/math] where [math]\Delta U[/math] is the increase in energy of a system, Q is the heat which flows into the system and W is the work done on the system. In the present case Q = 0 and W = work on water due to impact. This gives [math]\Delta U = W[/math] so the increase in thermal energy is due entirely to work done on the system (in this case the system is water). Pete

When I was training in Kung Fu I considered doing that but decided not too. The risk of damage to my knees from strain and jolting was too great. That's important to remember on this topic. While you might get the impression that muscle mass can increase without bound it really can't. Even with an increase in muscle mass due to strength training the speed of muscles won't neccesarily increase. So while your legs might get very powerful it in no way means that you'd set a record in high jumping. The training for height of jumps is different than that of strength training of legs. Pete

It is instructive to try this without relativity by working as follows: Calculate the force on a charged particle which is moving through the magnetic field. Since the force remains invariant in a Galilean transformation the force has the exact same value in the rest frame of the charge. By definition - The force due to the charge of a particle which is at rest in frame S is an electric force. This force can now be used to calculate the electric field measured in that frame. Once that field is determined one can then use Gauss's law to determine the charge denisty of the wire as measured in frame S. Pete

Very helpful. Thanks! Pete

I was wondering if someone here could recommend a biology text book for someone who wants to learn biology, basically from scratch. I'm interested in a college level text since I know the basics of biology. Thanks. Pete