Tensorman

It has an enormous amount of solid experimental evidence. Your computer, phone, dvd player and all other modern electronic gadgets can only exist thanks to tha application of quantum mechanics.


Nope. The famous Schrödinger cat paradox was a thought experiment by Schrödinger in the early years of quantum theory to describe the difficulty of the transition from QM in the microscopic domain to classical physics in the macroscopic domain. It was at the time not clear why the superposition of quantum states in the atomic realm disappeared for large objects (like cats), it seemed that only the fact of observation by a conscious observer destroyed the superposition, which gave rise to weird speculations about the importance of observing by a consciousness. However, this problem has already been solved long ago. The observer is not necessary, it is the phenomenon of decoherence, due to the interaction of the quantum system with the environment, that explains that there can be no superposition of an alive and a dead cat. The cat is dead or alive long before anyone looks into the box, just as classical physics predicts. Experiments have shown that superposition of states can exist for relatively large molecules like fullerenes, but these are still far from macroscopic objects, for which any superposition decoheres in extremely short times. It seems however that many popular accounts of QM are still decades behind the facts.

Rats and flies are still much too large, but such experiments have been done successfully with atoms and even relatively large molecules. Those can be brought in a superposition of states, also called 'cat states'. For larger systems the phenomenon of decoherence makes the existence of such states practically impossible. That is also the modern answer to the riddle of Schrödinger's cat: QM does not predict that a macroscopic system like a cat can exist in a superposition of two different states (alive and dead), it will always be either alive or dead. At Schrödinger's time this was not yet known, but today the fate of his cat is no longer a riddle, it has been solved years ago. But of course popular books still like to present such old ideas because they sound so mysterious. The same for the problem of a consciousness that seems to seal the fate of the cat (Wigner's friend theories), thanks to the decoherence explanation consciousness is no longer needed in the explanation, the cat is already dead or alive before anyone looks, in accordance with our macroscopic intuition (which works well for macroscopic systems, but fails at atomic scales, as we've never experienced those directly in our lives).

Why when you cross your northern border does crime drop dramatically? Canada has the same drugs problems as does every Western nation. Stop dancing around the issue and recognise what to everyone else in the world is crystal clear.

I could quote lots of unbiased studies on this issue whereas I know all that you can quote is biased politically motivated right wing "studies". You'll even have a conspiracy theory ready to espouse why its not the right wing think tank that is biased, its the liberal universities! So that's why I'm not going to quote any studies because I think you'll be impervious to them.

Also, those of you who think it is somehow immoral to have strict gun control should reread Rand's words I quoted above.

That something contradicts "known facts" doesn't mean that it is a logical contradiction. It can mean that our knowledge so far was not complete: what seemed to us to be incontrovertible facts, were not. So it seemed to us for centuries that time was a universal variable, for everyone the same. Now we know that this is not true, see the twin paradox, which breaks a law that we thought to be an incontrovertible truth. A famous statement by Arthur C. Clarke is "Any sufficiently advanced technology is indistinguishable from magic", the fact that something looks to us like magic doesn't mean that it is a contradiction, something impossible. A God who could use the most advanced technology you can imagine, could very well do things that would look like pure magic to us. A logical contradiction would be for example a triangle with 4 angles or a married bachelor, there is no way that these could exist, but the fact that a known law is shown to be violated in some cases is not a logical contradiction. You cannot disprove the existence of God by pure logic.

It may seem trivial to say that we travel through time just as time passes, but it's not quite as simple as that, as the twin paradox shows. The twin who returns after a journey through space with high speed (comparable to the speed of light) will for example find that his brother has aged more than himself or possibly died a hundred/thousand... years ago. In the reference frame of the Earth the twins "travel through time" with different "speeds". From the viewpoint of the twin who remains on Earth, the other twin travels really into the future: he can return on Earth at a time which he would never experience as a living being when he'd stayed at home.

Whether one can travel backwards in time is of course a different question, but that can't be trivially disproved from your armchair. The grandfather paradox can be avoided, so that isn't a definitive argument. Furthermore we (the non-timetravelers) wouldn't detect anything strange - everything would behave normally with the usual causal effects, only the timetraveler himself might experience a change in the history as he knows it. That makes the argument circular: we've never seen that history can change, but we could only see that if we knew how we could travel backwards in time. The fact that we don't know how to do something isn't the same as knowing that it can't be done in principle. An argument is that as far as we know we've never met a time traveler, but neither that is a definite proof. Suppose the possibility of time travel will be discovered in 10000 years. How likely will it be that they will time travel to our period? Who knows what the people (perhaps half or complete robots) at that time want to do or can do? There might be much more interesting periods they will want to visit, or perhaps it turns out to be increasingly more difficult to travel the further you go backwards in time, so that our period is off-limits.

That said, I should state for the record that I think it's very unlikely that traveling backwards in time is possible, as our current knowledge of physics doesn't give any indication in that direction (there are some theoretical possibilities, but these seem to have no practical solution), but the question isn't as trivial as often is suggested.

It may seem trivial to say that we travel through time just as time passes, but it's not quite as simple as that, as the twin paradox shows. The twin who returns after a journey through space with high speed (comparable to the speed of light) will for example find that his brother has aged more than himself or possibly died a hundred/thousand... years ago. In the reference frame of the Earth the twins "travel through time" with different "speeds". From the viewpoint of the twin who remains on Earth, the other twin travels really into the future: he can return on Earth at a time which he would never experience as a living being when he'd stayed at home.

Whether one can travel backwards in time is of course a different question, but that can't be trivially disproved from your armchair. The grandfather paradox can be avoided, so that isn't a definitive argument. Furthermore we (the non-timetravelers) wouldn't detect anything strange - everything would behave normally with the usual causal effects, only the timetraveler himself might experience a change in the history as he knows it. That makes the argument circular: we've never seen that history can change, but we could only see that if we knew how we could travel backwards in time. The fact that we don't know how to do something isn't the same as knowing that it can't be done in principle. An argument is that as far as we know we've never met a time traveler, but neither that is a definite proof. Suppose the possibility of time travel will be discovered in 10000 years. How likely will it be that they will time travel to our period? Who knows what the people (perhaps half or complete robots) at that time want to do or can do? There might be much more interesting periods they will want to visit, or perhaps it turns out to be increasingly more difficult to travel the further you go backwards in time, so that our period is off-limits.

That said, I should state for the record that I think it's very unlikely that traveling backwards in time is possible, as our current knowledge of physics doesn't give any indication in that direction (there are some theoretical possibilities, but these seem to have no practical solution), but the question isn't as trivial as often is suggested.