The more I learn in physics, the more mysteries I encounter. The more theories I learn about "what is", the more holes I find. This is very frustrating. One day I intend to solve all these problems, possibly with the help of tarot cards or beer or both.
Hi Adam, There is a reason why this discussion takes place in the "Frontier Physics" forum Please Register or Log in to view the hidden image!. The truth is that we indeed have good theories that describe how things work - the most fundamental "what" questions is exactly what we're trying to answer with high-tech theories such the stringtheories. There are several variants, and to be honest, I don't think we're going to find out which one is the most correct anywhere soon. I guess Max Planck could have been right when he said: "New theories do not prevail because they convince others and let them see the light, but simply because all opponents die out and a new generation, that is familiar with the theory, grows up" Please Register or Log in to view the hidden image!. But no reason to be pessimistic: the theories we have explain a lot of phenomena in terms of basic assumptions on how nature works. Quantum mechanics assumes a wave/particle duality for everything in nature, and it works darn well. The questions we're asking ourselves here are in the line of: "is it REALLY both a particle and a wave?". Allow me to give a question as an answer: "does it matter? do we need to know that ?". I think it doesn't matter and that we don't have to know all the answers to the "what is it" questions. Or like C'est Moi argued: "that is actually a wrong question". What most people seem to forget here (I also do that from time to time Please Register or Log in to view the hidden image!) is that science CANNOT hold the absolute truth. Science works by inductive reasoning: from a series of experiments we try to formulate a general law that predicts the outcome if we do that series of experiments again. We can never verify this law to be entirely correct since that would involve doing an infinite number of experiments - anyone up for an infinite life? What science does is model nature in a scientific (read: mathematical) formulation, and a model is never perfect; simplifications are made, assumptions are made and if in the end, everything seems to turn out well, this model is used for describing nature. The kind of questions science can answer are for example: "if I hold this pencil above my desk and let go of it, will it fall ?". The answer is obviously yes (no scientist will dispute that). But if you ask WHY the pencil falls, then you'll get a whole range of answers about gravity: "it's because of Newton's second law" or "the pencil follows a straight path in the curvature of spacetime". In the end, all these different answers relate to the different models of nature you use to describe the pencil falling (be it a Newtonian model of gravity, Einstein's general theory of relativity or an experimental theory of quantum gravity). The answer depends a lot on the scientist you're asking: does (s)he believe the assumptions the model makes, does (s)he agree with the simplifications or does (s)he wants a more detailled description ? So to conclude this part: the "why" and "what" questions are IMHO not answerable with science, only the "what if" questions. You could be asking yourself why a certain model of nature (or theory) is more popular than another model. I believe that there's no consensus on that either Please Register or Log in to view the hidden image! - as I quoted above, Max Planck thought it was a matter of time. Thomas Kuhn argued that no consensus is possible. Personally I think Henri Poincaré hit the nail on the head when he argued that the preference of one theory over another is simply a matter of convention: if both theories work, then it's up to the scientific community to decide which one they like to use. One of the best examples here is the theory of special relativity: you can use a perfect Euclidian world to describe relativistic effects (but that package comes with aether and unexplainable Lorentzforces that deform clocks and lengths) or you can use the Einstein/Minkowksi description which gives up the idea of aether, explains why clocks and lengths are deformed, but uses the assumption that the speed of light is a constant for all observers. Both theories work: they can both explain some of the wierd effects we see when going at high speeds. However, the scientific community choose Einstein's theory (probably because they didn't want those wierd deforming Lorentzforces to handle). But whatever theory becomes "mainstream" - it's entirely a human choice. It's not really the most appealing image of science, but IMHO that's the way it is: because of our human inability to know "everything", we can never say something for sure. Just my thoughts Please Register or Log in to view the hidden image! Crisp
Interesting post. My own view is that science is merely trying to understand the universe, that's all. So I can never understand when people say "science is a new god". Doens't make sense. Science is something we DO, like breathing or running. I see no cause for comparison with mythical beings. Nature didn't give us claws and armour; it gave us science, our ability to learn, make and use tools, et cetera. And it rocks. Well, that's my view, very simple. About the "speed of light is the same for all observers" thing. I thought that was more than merely an accepted convention. Seems to me it is a basic physical property which has been demonstrated hundreds of thousands of times in experiments. And there's not even anything tricky about it. All it says, to me, is that electromagnetic energy of a given type/flavour/whatever will always have the same velocity in a certain material. In our atmosphere, for example, regardless of how fast any observer is travelling, light will always travel at the speed C (a numerical constant around 300 million metres per second) divided by the index of the air. A very simple physical rule. If the object emitting that light is going twice the speed of light, it doesn't matter; the light may still only travel at the speed already defined for light in that medium. So yes, it seems more than convention to me; it seems a rather solid and reliable physical property. However, I don't yet see how that one physical rule about the propagation of light through various media restricts anything from exceeding that speed. I have not yet gone into the relativity stuff, the mass at nigh-lightspeed equations and all. Sorry for rambling and taking this thread off in all sorts of directions, but that's the way I learn things, by following my interest.
You are almost right with that last statement. The speed (note that speed is a scalar quantity) of light in a medium is dependant on, amongst others, two things. The relative permittivity and relative permeability of the medium, relative to these values in vacuo. When a wave front crosses a boundary between mediums it slows or speeds up immediately. (It does accelerate). This is manifest as the wave front changing direction, it refracts. The amount of refraction depends also on wavelength, which is why white light seperates into a spectrum through a refractor. In essence, the refractive index of a substance is a measure of the resistance to a light wave that the substance has. Important point here, the speed of light is scalar and is invariant between frames of reference. How then can a light ray accelerate? Acceleration is a change in speed OR a change in direction. If light changes direction it accelerates. So, as light always travels in straight lines and its speed is invariant how can it change direction. That which we perceive as a straight line in 3D space is curved but is a straight line in 4D spacetime. The amount of curvature is caused by gravity. I am using the argument the wrong way around. What Einstein reaised is that gravity and acceleration are indistinguishable. If light passes through a gravitational field IT MUST accelerate. The only way it can do this is change direction. But if space is euclidean it can not. Ergo, space is non-euclidean. In others, its bent, curved, twisted or whatever. If people want to dismiss Einsteins Relativity they have to first start with disproving the equivalence principle (gravity and acceleration are the same) then the rest of the argument. As some one pointed out, the gravitational lenses that have been found are powerful evidence of the validity of Einsteins work.
Background reading About optics and permittivity, permeability, refractive indices. http://www.cem.msu.edu/~cem835/Lecture03.pdf Also look 'optical path'
It's truly wonderful how many clever people still get it wrong when discussing theories. I believe Crisp explained it very well. And I believe my quote of Aspden made that one very clear also... http://www.energyscience.co.uk
Many people on this board are claiming that photons have no mass and their paths curve when passing large masses because the large masses curve space. Yea right!! Unfortunatly, many people on this board are "textbook geniuses" and unable to think for themselves. Their answer for all questions regarding physics is "Cause Einstein says so!" For a second, let's assume Einstein was right and photons do not have mass. Maybe people don't have mass either. Maybe we are just held to the Earth by the Earths curved space!! Tom
Tom, if photons had mass they could not travel at c. Since they do travel at c, they have no rest mass. End of story. They still have apparent mass, which comes from their motion. So they are still affected by gravity (whatever you may think it is) because of this mass gained from their motion. Your arguement that photons do have rest mass is flawed in that it contradicts almost every observation made concerning photons and the speed of light.
cest moi, It is disappointing to see Harold and Dennis's names brought up in scientific discussion. But perhaps you've brought in the aether twins as a humorous interlude? If so, thanks, I had a good chuckle.
I saw in either New Scientist or American Scientist recently a huge article or set of articles about the "aether" or plenum or whatever they want to call it now. There are a LOT of researchers in many countries who believe there MAY be something to it, and who have found unexplained phenomena in their experiments which MIGHT lend credence to such ideas. Whatever the truth, they aren't yet ready to rule it out completely. I think it is far too early for people to dismiss that whole thing as fairy tales. I'm quite happy with the idea that photons (whatever people think they are) have no rest mass at all. However, I also think in this case that it is far too early to say "end of story". There's far too much we don't know, in both those cases.
"It is disappointing to see Harold and Dennis's names brought up in scientific discussion. But perhaps you've brought in the aether twins as a humorous interlude? If so, thanks, I had a good chuckle." no thanks m8 maybe you good give some argumentation now that clarifies your answer why is aspden able to derive the law of gravitation without using relativity, using maths and logic that normal people still comprehend? occam's razor cuts very sharp here
why is aspden able to derive the law of gravitation without using relativity, using maths and logic that normal people still comprehend? You can use math and logic to satisfy the concept of wormholes and white holes, but the reality is very different. occam's razor cuts very sharp here Not sharp enough I'm afraid. Special Relativity came along and occam's razor sliced right through. Please Register or Log in to view the hidden image! So much for the redundancy of the aether theory. I'm starting to get the impression that you're inferring there is a problem with SR?
Joeblow Right then let's assume that Einstein is wrong. As is every one who came after and a few before. So, first question is, what is light? Is it a particle or wave. Newton realised that shows properties of both. Maybe we should do some experiments to investigate things. After all, the thousands of experiments and conclusions found in the last 150 odd years are all wrong. Any ideas? What does light travel in? If its an Aether that Aether exists every where. This means it must have zero density, other wise you would feel it dragging on you. Assuming it carries waves it must have infinite elasticity, otherwise light would loose amplitude, quickly. Do you know any infinitely elastic but zero density materials? Actually, its an absurd idea so I'll wait for your answer. How about this electricity and magnetism stuff. We can assume Maxwell is wrong, after all his theory led into Relativity. So what are they? Why does a moving magnetic/electric field create the other? How about atoms? Mass, energy equivalenc forms a cornerstone of QM so we can throw out every thing we know about atoms, its based on Relativistic concepts. Any ideas? What is matter made of? What is charge? Hmmm, strange that Physics is so wrong yet it built an Atom bomb, radios, broadcast, silicon chips, predicted the cosmic microwave background, predicted the displacement of stars positions by the Sun, Black Holes, gravitational lenses etc. Maybe you have a better explanation than those boring physicsts how are 'text book geniuses'.
Do I believe in materials with zero density or infinite elasticity? Belief is irrelevent. Three hundred years ago people did not believe in nuclear weapons, lasers, GPS systems, and mircowave ovens. The question is pointless. Talking about the aether like that is, in my beginner's opinion, very bad science. Saying it would have to be zero density, so it doens't exist, et cetera. What you are doing there is saying "According to what we know now, that CAN NOT exist. So it's really stupid to look for furtehr information about the universe." Obviously science would not have progressed very far if there were too many people like that involved. The fact is we do NOT know what we can not yet detect. To say that therefore it is not real is presumption and detrimental to the goal of science, that being to learn about the universe. I don't think anyone in this thread has said physics is wrong, that Maxwell's equations don't work, et cetera.
thed, I'll try to answer some of your questions, but I don't know everything either. What I do know is that Relativity DOES NOT make sense. There are more then one way to explain a phenomena and Einstein's way was wrong. "So, first question is, what is light? Is it a particle or wave. Newton realised that shows properties of both." Thank you for admitting that photons are particles. I guess since the main property of a particle is mass, a photon must have mass. There goes Einsteins theory about photons being PURE energy. "What does light travel in? If its an Aether that Aether exists every where. This means it must have zero density, otherwise you would feel it dragging on you. Assuming it carries waves it must have infinite elasticity, otherwise light would loose amplitude, quickly. Do you know any infinitely elastic but zero density materials? Actually, its an absurd idea so I'll wait for your answer." Very foolish question. You assume that all matter must exert a drag on other matter. Does a superconductor exert a drag on the electrons traveling through it? Does the strength of the electron's electric or magnetic fields diminish with time as it travels in the superconductor?? I guess a superconductor must have "zero density and infinite elasticity""!!!(sarcasm). "How about this electricity and magnetism stuff. We can assume Maxwell is wrong, after all his theory led into Relativity. So what are they? Why does a moving magnetic/electric field create the other?" Funny you should ask me. Wasn't it Einstein who completely ignored magnetic and electric fields. Answer this : What is Einsteins theory for the attractive and repulsive forces of electric and magnetic fields??Oops, he doesn't have one. He had a crazy theory about curved space but it ONLY applied to gravitational fields. "How about atoms? Mass, energy equivalenc forms a cornerstone of QM so we can throw out every thing we know about atoms, its based on Relativistic concepts. Any ideas? What is matter made of? What is charge?" Interesting that you should mention E=mc^2. As far as I know, most people don't even have a definition for energy. What is you're definition of energy? Try contacting a physicist who worked at Los Alamos in the 40's. Ask him/her what they thought about E=mc^2 after they detonated the first atom bomb? You'll be surprised!! "Hmmm, strange that Physics is so wrong yet it built an Atom bomb, radios, broadcast, silicon chips, predicted the cosmic microwave background, predicted the displacement of stars positions by the Sun, Black Holes, gravitational lenses etc" I never claimed physics was wrong, I claimed Einstein was wrong. Unlike you, I don't believe that Einstein and physics are one and the same. Tom
Thank you for admitting that photons are particles. I guess since the main property of a particle is mass, a photon must have mass. There goes Einsteins theory about photons being PURE energy. So if photons are simply particles, would you mind explaining how they set up interferance patterns in a double slit diffraction experiment? If they were only particles, you would expect just a random spattering of dots on the photoreceptive plate wouldn't you? But alas, that doesn't happen. Any ideas? He had a crazy theory about curved space but it ONLY applied to gravitational fields. So? Try contacting a physicist who worked at Los Alamos in the 40's. Ask him/her what they thought about E=mc^2 after they detonated the first atom bomb? You'll be surprised!! Why would I be surprised? I claimed Einstein was wrong. You may claim all you wish. Nevertheless, the vast majority of experimental data conforms to the theories of Relativity. Calculations involving relativity are made every day to a very high degree of accuracy. Atomic clocks accurate to tiny fractions of a second have revealed a difference in the passage of time at different lengths from Earth's gravity well, just as Einstein predicted. Experiments in particle accelerators have found we can accelerate say, an electron to 99.99% the speed of light, but not quite over it. Just as Einstein's theories predict. The radioactive half lifes of particles have been observed to double, triple, quadrouple and more in particle accelerators when travelling at close to light speed. This is due to the slowing down of time relative to the particle, just as Einstein's theories suggest. All these things, and many more, have conformed almost exactly to relativity, and yet you are here trying to convince me it's all absurd without even going so far as to provide an alternate theory.
Thed said: "So, first question is, what is light? Is it a particle or wave. Newton realised that shows properties of both." Joeblow said: Thank you for admitting that photons are particles. Read carefully Joeblow, Thed said specifically "shows properties." It was already mentioned before the photons exhibit properties of momentum and energy. It could also be shown that a baseball bat can exhibit particle and wave properties. Please Register or Log in to view the hidden image!
Xelios, "Try contacting a physicist who worked at Los Alamos in the 40's. Ask him/her what they thought about E=mc^2 after they detonated the first atom bomb? You'll be surprised!! Why would I be surprised?" I can't be sure, but when I was younger I heard from a physicist that the detonation of the first atomic bomb surprised the physicists at Los Alamos because the explosion was more powerful than the formula E=mc^2 indicated it would be. "So if photons are simply particles, would you mind explaining how they set up interferance patterns in a double slit diffraction experiment? If they were only particles, you would expect just a random spattering of dots on the photoreceptive plate wouldn't you? But alas, that doesn't happen. Any ideas?" I didn't say that photons were only particles, I said they were particles. And as such, must have mass. And as I said before, there are different ways of looking at things. Here's an example. Lets say you lived during the Roman Empire and you believed that the world was flat. If you held a rock in your hand and then dropped it on the ground, you could argue that you and the Earth rose up to meet the ball, instead of the ball falling to meet the Earth. You may even be able to prove it using formulas and equations. But your theory would be wrong. The only way to prove that you were wrong would be if you stepped back and looked at the whole picture. Einstein made a similiar mistake. When you look at things locally, relativity may be able to explain them. But when you step back and look at the whole picture, then you will see that relativity no longer makes sense. Example: Time slows down when matter approaches light speed. Is time seperate from matter? Could it be that time is constant but reactions are slower? A catalyst will speed up a chemical reaction, but won't it appear as if it's making time go faster? Example: An object can never reach light speed because it's mass would be infinite. What about super blackholes, like the ones in the center of galaxies. Wouldn't their be enough distance and gravitational force to speed up an incomming object to c? If you can't push an object to c because of it's mass, what about pulling it with gravity?? Example: Gravity is the result of curved space. What about the forces in electric and magnetic fields? Are they also the result of curved space? If not, can gravity be explained using the same theories that would explain magnetic and electric fields? As you can see, physical phenomena can be looked at in different ways. As you know, there are already people claiming that they can prove all relativistic phenomena using only classical physics and common sense. What would you prefer: explaining the universe using relativity and classical mechanics, or explaining the universe using ONLY classical mechanics? I would prefer the latter. So finally, do I have a theory that would replace relativity? The answer is no, but I'm working on it. Unfortunately, I'm not a physicist so I can't spend my entire day trying to prove Einstein wrong. But believe me, one day someone will come along and prove that Einsteins Theory of Relativity is wrong, and everyone will be wondering why they ever believed in such an illiogical theory. Tom
I can't be sure, but when I was younger I heard from a physicist that the detonation of the first atomic bomb surprised the physicists at Los Alamos because the explosion was more powerful than the formula E=mc^2 indicated it would be. I doubt it. Nuclear reactions are not even 100% efficient at converting matter to energy, so if anything the energy created would have been much less than predicted by E=mc^2. If you can't push an object to c because of it's mass, what about pulling it with gravity?? It wouldn't matter if you pushed or pulled, accelerating a massive particle to light speed requires infinite energy, which is why it can't be attained. What about the forces in electric and magnetic fields? Are they also the result of curved space? If not, can gravity be explained using the same theories that would explain magnetic and electric fields? Possibly, however at the moment curved space is the best answer to the gravity question. If gravity were a field you would have to explain how the light from a star bends around a massive object such as the sun (which is visible during an eclipse). But believe me, one day someone will come along and prove that Einsteins Theory of Relativity is wrong, and everyone will be wondering why they ever believed in such an illiogical theory. I doubt it will be completely wrong. At the moment it does it's job very nicely, perhaps a century from now we will develop a new understanding about physics and formulate new theories that differ from Einstein's, but I'm sure they will incorporate some of the same concepts. Einstein may be partially wrong in the long run, but to call his theories absurd is just naive.
Joeblow, <i>Wasn't it Einstein who completely ignored magnetic and electric fields. Answer this : What is Einsteins theory for the attractive and repulsive forces of electric and magnetic fields??Oops, he doesn't have one.</i> I don't know where you get your information about Einstein from. His first paper, introducing special relativity in 1905, was titled "On the Electrodynamics of Moving bodies". Yeah, he didn't incorporate electromagnetism. Right. LOL. Please Register or Log in to view the hidden image!
