From: cruyff 28/06/2001 11:35:27 Subject: Laws of physics post id: 334504 When physisists debate certain issues they often disclaim things with the notion that "its not possible because it defies the laws of physics". This argument could well have been used hundreds of years ago only to be later proved wrong. My question is.....How rock solid are the laws of physics as we know them now....Do you think that one day they could be proved wrong or have we reached a point where they are undeniably right? From: Zardoz ® 28/06/2001 11:40:21 Subject: re: Laws of physics post id: 334511 How rock solid are the laws of physics as we know them now. Do you think that one day they could be proved wrong or have we reached a point where they are undeniably right? Any scientist that stops asking questions and accepts things without thought has lost the battle. Evidence points to a fact or theory and that will remain as such until a new experiment or discovery is found that overturns the apple cart. From: Steve 28/06/2001 11:41:47 Subject: re: Laws of physics post id: 334512 Do you think that one day they could be proved wrong or have we reached a point where they are undeniably right? Absolutely! That's how science works. It moves forward in a series of paradigm shifts. Once the current model is proven to be faulty and a theory comes along that better explains what is being observed, then it is adopted. General Relativity did this to Newtonian mechanics. It does not, however, make Newtonian mechanics wrong. It just means GR is a broader theory. From: cruyff 28/06/2001 11:45:34 Subject: re: Laws of physics post id: 334522 So it is in fact possible that one day the laws of physics may change and someone will build a perpetual motion machine From: James R (Avatar) 28/06/2001 11:46:26 Subject: re: Laws of physics post id: 334524 Something becomes a "law" only by having a lot of supporting evidence and no apparent exceptions. However, every law of physics is provisional. If future observations show that the law does not hold, the law must be thrown away. Having said that, practically all of the things physicists refer to "laws" have huge bodies of supporting evidence, such that most physicists would be more likely to doubt an experimental result that went against the law than to doubt the validity of the law itself, unless the evidence was exceedingly strong. Newton's laws of motion are tremendously accurate and almost universal in application. Newton's gravity is tremendously powerful and accurate, but we found last century that it was not totally accurate. In that case, Newton was not thrown out, but was realised to be a very accurate approximation to an even more accurate set of laws. Similarly, Newton's laws of motion themselves are now recognised to be (only!) a tremendously accurate approximation to the laws of quantum mechanics, also established only last century. What of quantum mechanics itself? Among its many successes, quantum electrodymamics accurately predicts some features of nature to over 12 significant figures. That is incredibly accurate. JR From: Robert ® 28/06/2001 11:51:49 Subject: re: Laws of physics post id: 334538 Yes, but that's about as likely as the speed of light slowing to a few meters per second, or gravity suddenly switching direction. Perhaps thermodynamics breaks down in really extreme circumstances, though, which are as yet untested? From: James R (Avatar) 28/06/2001 11:51:54 Subject: re: Laws of physics post id: 334539 Regarding perpetual motion machines: The laws of thermodynamics are among the set of physics' most highly supported laws. They work in both classical physics and in quantum physics, and their predictions have been borne out over and over. I will be VERY surprised if a working perpetual motion machine is ever invented. From: Pete ® 28/06/2001 11:57:49 Subject: re: Laws of physics post id: 334555 My question is.....How rock solid are the laws of physics as we know them now.... Just to clarify briefly what you already implied: The laws of physics are rock solid. Our knowledge of them is limited. So if something defies the laws of physics, it's definitely not possible. The question is how good our knowledge of the laws is. And to answer your question, it varies. Some parts of the laws of physics we know extremely well. Other parts we're still guessing at. Do you think that one day they could be proved wrong or have we reached a point where they are undeniably right? Let's take Einstein's Special Theory of Relativity as an example. This is the one that implies that nothing massive can accelerate to the speed of light as measured in its local space. It is technically possible that the theory ay be proved wrong. When an experiment is performed to test a theory, the results are analysed and rated against the probability that they could have happened by chance. We can do experiments to test special relativity that give results that the theory predicts, with a probability of less than 1 in a billion of being a coincidence. Those experiments have been done over and over and over again by many scientists around the world, and everyone gets the same results each having a chance of 1 in a billion if the theory is wrong. So, the chance that the theory is, in fact, wrong becomes astronomical, particularly when more theories are developed on the basis of an existing theory, and the new theories are tried and tested in the same way. Note that theories can be incomplete without being wrong. A classic example is Newtonian mechanics and gravity, which were refined by Special and General Relativity. Newton's laws are still correct, but have certain limitations as defined by the newer theories. From: cruyff 28/06/2001 12:30:54 Subject: re: Laws of physics post id: 334608 Just to simplify it a bit. To my way of thinking some things are just impossible. For example... it is impossible to acceleate any mass to beyond the speed of light. It is impossible because the laws of physics say so. The mass of anything travelling at the speed of light would be infinite, and as that is impossible, the logical conclusion is that the law must be true and beyond any question. Therefore this can never be superceded by any other law and is rock solid. This forum is un-moderated. The views and opinions expressed are those of the individual poster and not the ABC. The ABC reserves the right to remove offensive or inappropriate messages.