Modern and Theoretical Physics

the other day i found myself in a heated debate with two of my friends about infinite possibilities. their claim was that while adhering to the belief that the universe is infinite, any kind of planet that could possibly exist WILL exist. they used the example of a planet 100% identical to ours, the only exception being everybody spoke spanish. taking what i know about infinity and numbers, and how an infinite set of numbers does not necessarily need to contain every number that there is i argued with them, saying that while it is possible that this planet could exist, it does not HAVE to, if there are infinite possiblities of planets that could exist, than th…

Can someone explain to me (without loads of maths!) the phonon. I've been reading here: http://en.wikipedia.org/wiki/Phonon but don't understand all of it. They seem to be to do with vibration of atoms in a solid, possibly to do with wave-particle duality, you have a wave in a solid (caused by sound, or thermal energy?) and that's the wave, the phonon is the particle. But I'm not really sure, if a photon is part of the EM spectrum making light, the a phonon is _________ what?

Hi In the decay of U238 -> Th234 + He4 why He come out ionized ? The nucleus of U is surrounded by 92 electrons and when the alpha particule is emitted by the nucleus it must goes through this cloud of electrons. Why doesn't the alpha particule doesn't capture the two electron it is missing to get electricaly neutral ? What happen to the 2 excess electrons left on the Th atom ?

Just watching the episode now; what do you think? For those of you who dont know; There is a way of making a bubble glow using just sound, the bubble once exposed to the sound waves expand and then collapse creating Immense heat. Enough heat for fusion to occur? Experiments so far appear optomistic. Ill psot a link when i find one

Hi, I'm new to this forum, and I have a question. OK, matter can be neither created nor destroyed. If that's the case, has the matter which our bodies are made of existed in one form or another for as long as the universe has existed? To put it another way, when our bodies grow and get bigger, is matter being adding to the universe, or did the matter already exist but is now simply in a new form?

What is the difference between them? from what I see: Fourier’s law states that rate of heat flow is proportional to the gradient of temperature difference. whereas: Newton's law of cooling states that the rate of heat loss of a body is proportional to the difference in temperatures between the body and its surroundings. so fourier's: heat flow (proportional) difference in temp between system and surroundings newton's: rate of heat loss (proportional) difference in temp between system and surroundings but couldn't you call heat flow (fourier) - loss of heat from one part of the system (newtons) and gain in the other? what is the precise di…

Would it be possible to create matter from energy? Like a reversed nuclear reaction? Has it been done? How would it work? I can only assume it would require massive amounts of energy, and would not have any practial near-term applications, but maybe a possibility for propulsion in interstellar space travel in a few thousands of years? Create matter from energy -> gravity pulls spaceship -> Convert matter back to energy -> back to step one

Hi everyone, I was looking at the Dyson Sphere concept and a thought struck me, how would the energy collected by the Sphere be delivered to Earth? As a battery retreival system with a shuttle would be too expensive and i know little of wireless way to transmit the energy. Any help or guidance would be great.

Consider the landscape of string theory, with its bazillion of different vacua, each vacua representing an universe. Is possible to travel to another vacua? If our universe is one of these vacua, can we travel to another vacuum? Is possible? Using a Black hole? Ideas, please

What makes the difference (atomically and chemically) between a red substance and a blue substance? I heard it was to do with the electron's osciallation (or frequency?) and it was to do with that and the oscillation (or frequency?) or the photon? What i want to know is what makes some objects only emit (after absorbing) a photon of one frequency and not another?

Dear Sirs: I have posted this Question all over the web, physics forums, science magazines, academics in plasma physics and condensed matter, I have received little response. Can you be of assistance? I thought this might interest you. I have been researching Hydrogen-boron Fusion. Here's the most important posts, if this technology is real, it's history changing. In my searches for efficient home technology I came across Electron Power Systems. I E-mailed EPS about the obvious synergies for their home generator with the power chips of Borealis. I also contacted Borealis. I have been mediating an argument between Clint Seward of Electron Power Syst…

hi! i came across this questionin class and to tell you honestly, i have no idea as to the answer to the question.. so i badly need your help.... thanks a lot! here it goes: What do you think would be different in everyday life if the speed of light were 10 m/s instead of its actual value?

My theory. I was in the shower earlier. I was bored, so I started thinking about all the things I had recently learned. I had just got done reading a book called Strange matters, and I remember it said that nobody could really think of what physical importance multiple time dimensions could have upon our universe. I do realise that the book is a few years old, but meh, and I did do some research on Google, but I didn't see anything that seemed to reflect my theory. If someone already came up with this (like what happened with my theory as to spontaneous human combustion!), I'd like to know. If I'm so utterly and totaly wrong, please inform me nicely, I'd like to learn…

In the future, lets create an Magnetic Accelerator in the earths orbit spanning the entire orbit so huge that will accelerate a small magnetic material space ship to near speed of light then release it in the desired stars direction. Advantages : 1) We get instantaneous speed of light just as we would leave earth. 2) We don’t require to carry bulky fuel to achieve speed of light. 3) A similar magnetic decelerator can be used to decelerate without need of fuel to do so at the destinations. 4) Because time slows down at near light speeds we don’t need to carry much of human needed cargo for the travelers as they may reach the destinations in a day or mi…

I have understood the general concept of electromagnetic waves since I was at school, and now I have delved into the harder part of physics with an extended desire to study astrophysics. I was taught at school that light is within the visible part of the electromagnetic spectrum, and so we perceive light and it's frequencies as colour through light. But what I had failed to recognise was that light doesn't really have a spectrum of colours but a spectrum of frequencies that we perceive as colours. So this had become a shock to me because now I have had to realise that colour is psychological and not physical as we would apprehend. I think schools should point this out…

I have read that subatomic particles are made up of a type of quantum foam. I read that there is enough energy in the foam of one atom to instantly boil every ocean on Earth. Scientists are now building particle accelerators and smashing atoms together. Doesn't it seem careless to smash atoms together? Wouldn't this take a chance of releasing huge amounts of energy that could destroy the world?

Whoopee, I'm quite certainly getting to borrow an over 2000$ Geiger-counter that can even detect different isotopes through observing the decay... something (the energy of the gamma photon perhaps?). I'm going to: A) Find a couple of broken smoke alarms and see how much the americium-source shows B) If I ever get my U-ore sample, see how active it is C) Going to scan every single place in case someone has hidden plutonium rods there ) Any other nice stuff to monitor? I guess it's quite a sensitive counter, so weak sources are OK too. Perhaps swansont could lend me some thorium targets... )

Can someone please explain to me where atrraction or repulsion come from, i mean what fundamentally creates something of an electric charge? where does magnetism come from?

http://www.bnl.gov/rhic/images/movies/collision_movie-lrg.mpeg movie of a gold on gold collision at relativistic speeds the two gold ions approaching each other look like pancakes because they are flattened (from the stationary observer standpoint) by going near the speed of light this just a movie but the real thing is done at the RHIC (relativistic heavy ion collider) for a moment they think, there is so much energy in the little fireball when the two golds collide that protons and neutrons boil out their quarks so there is a cloud of free quarks and gluons but it quickly cools (back to more normal particles) and expands Here is a general discr…

I read here and there that massless vector bosons carrying forces (e.g., the photon carrying electromagnetic force, or (if exist) the graviton carrying gravity force) can travel faster than light. I have never read tho' if there's a limit for that velocity, so I'm interested to know that limit, what's the maximum velocity that can acquire virtual particles Bye

Arnold Neumeier a prof at the University of Vienna and a Quantum Field Theory dude put a "theoretical physics FAQ" online a day or two ago http://www.mat.univie.ac.at/~neum/physics-faq.txt might interest some SFN people (since I am not an expert i cannot certify this, but he seems to be very much respected and on top of the subject so I'm guessing this is a good FAQ)

As a small experiment, I put my mobile phone in the microwave (microwave is off) and called that phone with my cell phone. The mobile phone worked fine, despite being inside the microwave with the door closed. I am confused about this. I was under the impression that the mettal grid that blocks the microwaves is simply a faraday cage, and hence should block all EM radiation at or below a certain frequency. The mobile phone opperates on 2.4Ghz. Microwaves use 2.45Ghz for cooking, according to wikipedia. My question is how the phone signal was able to get through the microwave.

Ok, this is actually a question. I'm not that big on string theory anymore, mainly because I don't think it's science, but this thought just struck me the other night. Strings are actually energy, in the form of branes. At absolute 0, all energy is lost. Would such constitute the disappearance of ordinary matter? Or what about the expanding universe? Strings loose their energy to the expansion. What happens if they lose to much energy? If they stop giving it away then expansion stops. But if they don't then matter, again, jsut simply disappears (dont forget abotu leptons and the like a well. Everything would actually cease to exist!).

http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v433/n7021/full/433012a_fs.html by quantizing the basic equation of cosmology and developing a quantum cosmology Bojowald already in 2001 showed that there is no singularity at the big bang. the model extends back further in time it quickly converges soon after the ex-singularity to resemble classical spacetime Bojo model is called LQC, loop quantum cosmology. It even naturally generates an inflationary episode immediately after the crossover from contraction to expansion and a graceful exit from inflation, which is generic in the model---i.e. requires no elaborate extra assumptions …

I was jus wondering........I have read many chemistry books throughout my life and taken numerous chemistry classes...but i have yet to have heard another name for the zigzag line which separates metals from nonmetals...doesnt "zigzag line" sound a little "unscientific"? im sure there is another name for it and if anybody knows please reply on this thread....thnx