Modern and Theoretical Physics

well to be honest i didnt know what to call this thread!!! if i take my thumb or any finger (average sized) and place my laser pen on the other side of it i can see the red light through my finger... not as powerful as if it there was no finger... but significantly, or enough to clearly notice it. as i move the laser down my finer it becomes fainter (the top of my finger must be slightly thinner) and even through my palm i can (a very tiny bit) see it... however my arm and pressumably most of the rest of my body is too thick to let the light through (no rude comments about certain areas of the body please ) so my question is how are the photons from the laser …

All right, I'm formulating a new idea. See page 2, starting from post 3.

It's hard for me to imagine a pulling force. I cannot in my most maddenned of states bring myself to believe in a force that moves objects in the opposite direction to which it moves, so I have come up with this... When EMR hits something, that something tends to heat up, and tends to move away from the source of the EMR. That was a particle with momentum, which it transfered to another particle. The particle hit by the EMR assumed part of its properties. Now imagine the opposite and extreme version of that scenario. A particle is emitted by some matter. The particle then interacts with some more matter. This time, the particle assumes the properties of the …

Think it would be possible to make some sort of extremely sensitive gravity sensing device that could image gravity fields like the way we can image electromagnetic and sound fields now? A monochromatic view of the world based on the ammount of pull it has on the detector. Imagine looking at the stars with that!

We have seen that out kitchen fridge magnets stay attached even though gravity is acting on it (and other forces too). I dont get it that how come there is infinite energy in it to defy gravity?....wats the reaction of the action?......some explaination my friends gave : : 1. The total energy is reducing by time(takes millions of years)....I dont like this theory. 2. Maybe everything is happening inside the magnet. The minute circular loops of current which sustains the magnetism is constant...like the stability of a proton electron system!? Thank you !

OK..... (some background stuff) E.G. OR Can somebody expand on those two. Severian's: i dont see which part of the light beam is moving faster than c... because, the light beam would (i have thought) always have been moving at c, so where is this wrong? Swansont's: what is the "pulse peak"? for example in this image: are you saying that the violet would come out "quicker" than it was meant to as it is taking a shorter route through the prism than the original white light beam? also surely the fact its going through a median (glass prism) slows down the light anyway?

A friend of mine was trying to convince me the other day that thought can travel faster than light. His example was this: you take a stiff rod of some solid enough material and long enough length (long enough for light to take a humanly noticeable amount of time to travel). Take two people and put one at each end. Have one person send a message to the other by pushing on the rod length-wise (that is, on its end). Have the sender do this according to some binary code (like moris code). The recipient will receive the message instantly (faster than light) therefore proving that thought (or information) can travel faster than light. My qualm with this scenario was that I …

I know that the first 3 dimensions are width, height, and length. However, science magazines are talking about how there could be many more dimensions. One scientist said that there are probably at least 20 dimensions. What are these new dimensions? The first 3 dimensions seem to enable us to move in all directions. If there are any more dimensions, what are their properties? Can we exist in them? Do other life forms exist in them?

It came to me all of a sudden that I was unable to define scientifically the concepts of distance and time, without of course in turn using a parameter which is a consequence of these two concepts, velocity. So somehow it comes in a whole loop back on itself, which is frustrating. Sure, we say that time is "how long" it takes, but I find that a rather unacceptable definition scientifically. Distance is how many ruler lengths something is, which is again not precise with all the things such as general relativity and other theories out there that totally mess up intuitive definitions. Any ideas? Though I think this may turn out to be a stupid question, but I thought…

Most people agree on the theory a giant explosion created our universe and it is mostly known as the big bang, initialy a expanding energy in a plasmatic state. If there was an inconsistancy in hydrogen distrabution which happend hydrogen would eventualy make helium by colliding but what if our universe was a perfect expanding ball of hydrogen never able to to make anything else how could a physicist figure that out and is anything in what I said even possible lol?

Does anyone here have any thoughts on string theory? The way I have understood it, Mitchiel Kacoo(sp?) says that the particles that make up atomic particles, quarks and such, vibrate (using whatever energy) at a certain frequency? What more, is that it states that these "particles" are not actualy praticles, but are actualy wiggling strings", and that the number/type/frequency of vibration determine the Sub-atomic particle created (Neutron, Proton, Electron, ect.) so in a manner of speaking, if one could control the vibrations of these sub-sub-atomic particles, you could in theory change ANY form of mater into anything else with the same mass; Sort of the "Molecular…

Hi, I'm in the first year of my materials science bachelor degree. Having learned elementary laws about forces holding atoms together and such, I'm thinking about programming an applications incorporating this and see if I manage to get orbitals similar to what observed. I'm sure this has been done lots of times by lots of people, so any tips before I start is appreciated. Basically, how far will I get by creating a particle based model using electrostatic repulsive/attractive forces (Coulomb's law) and a opposing repulsive force from the nucleus (inverse of cube of distance is it?, haven't learned this yet and don't know what it's called)? As for electrons shie…

I was wondering if anyone has found the smallest particle yet. I know about protons, neutrons, and electrons. I've also heard of quarks, but I don't really know what they are. How far does matter break down? Have they found the smallest particle?

Does this make sense to anyone? A man traveling faster the speed of light reaches a distant planet. Because of his speed, he reaches his destination before the light from his starting point, thus it appears that he has reached his destination before he arrived, and traveled back in time.

mathematically speaking, how are they constructed and what kind of operations are performed on them that make them useful in describing the multi-dimensional universe in superstring theory?

What do you think of Strings Theory? Any good links to it?

a compressed spring has more energy than an uncompressed spring. gravity is not only affected by mass but also energy. how compressed must a spring be for it to have noticible extra gravity?

While reading Isaac Asimov's book "ATOM" I came across this paragraph and it seems difficult to believe, I am wondering if it is a mistake? Here is the paragraph exactly as it is in the book: The positron behaves exactly as Dirac's theory suggested. It quickly undergoes mutual annihilation when it encounters one of the numerous electrons in its immediate environment, producing gamma rays of energy exactly equal to that of the combined mass of the electron and proton. Well, that is actually half the paragraph, but the other half is unrelated to the error. My problem is with the word proton. Was it supposed to say positron? Because it seems like your getti…

Is there a way to find the frequency of emmited radiation of a black body when only the temperature is known? Does it depend on the material, another quality, or is it possible at all? Perhaps this doesn't reffer to black body radiation at all, but from what I've read it seems to be what I'm looking for. I just think of something like the tungsten in light bulbs. At very high temperatures, it emites light in the visible range. Is there a way to (preferably simply) explain this relationship?

hi all gurus, does anyone know the therapeutic index of plutonium? thanks

Hello, since I really know nothing of physics I would be greatfull if I could get answers for questions bugging my mind. 1. If from a viewpoint of an observer at rest, the mass of a moving particle approaches infinity as the speed of the particle approaches the speed of light, then why according to the observer at rest doesn't the "pull" of gravity originating from the moving object approach infinity? 2. What does a (matter) wave in quantum physics mean? What's so wavy about the matter? I know they call a wave on a string a wave since a point of the string oscillates between 2 fixed points. Also electromagnetic radiation is said to be a wave since its the result o…

Hi all, First off, I'd like to thank all moderators and members of this forum for answering my questions in the past, as they've shed tons of light on my understanding of the world. Anyway, here comes another one. I've been reading through the particleadventure website (highly recommended) and I stumbled across a certain model for how electromagnetic fields interact with particles to give them a push: http://particleadventure.org/particleadventure/frameless/accel_ani.html According to this model, particles "surf" the electromagnetic wave. But after thinking about this, I can't conclude anything other than that this model only works when the charge of the f…

if you could modify a higgs field in such a way to change it's energy, then you could make it have negative pressure, correct? enough negative pressure will make gravity repulsive. so, i was thinking that maybe in 10000 years or more we will have the technology to atrificially play with higgs fields. it would make for nifty space travel(modify higgs field behind the craft). is this right or am i way off?

OK, tried to calculate the activity of U-238 with Bq as activity units. Got about 9000 disintegrations per second in a gram of U-238. Is this anywhere near the correct value? If not, then I'm rather pissed off since I calculated it quite long. Where could I find the listed activities / mol?