Modern and Theoretical Physics

I am studying physics. A recent holiday found me in the lab with some laser equipment. Having been facinated with Star Wars from a young age I set about wondering how to make a lightsaber. The problem is not in the laser beam, but how to stop it at a certain point. One possibility was a mirror on a piece of wire that would be projected under the power of the light photons to the projected length of the retainer. The other possibilty would be using the same concept, but merely tethering a small black hole to the end to absorb the laser. What problems could this cause? Could it be done? Sorry if this is the wrong thread, but would love some input.

Hi again everybody, I just heard about an idea that Nikolai Tesla had back in 1891 for a wireles powerplant. I have also heard that work related to this was also done by a mathematician called Schumann in the forties, hence the name Schumann cavity. I was just wondering if anybody knows about this idea and whether you would consider it at all feasible? Also I am not sure how such a device could actually work so I would be very grateful if anybody could offer an explanation. Thanks a lot:-) .

I need to magnetize this crankdrive from my motorcycle for experimental purposes so if anyone can help me out it would be appreciated.

Let's say I have two pairs of identical magnets. The first pair is 1 Tesla. The second pair is 2 Tesla. If I have unlike poles facing each other as below, would the total force on the balance be the same? 1T2T 1T2T Balance 0r 1T2T 2T1T Balance

Hi. does anyone know what the problems produced by the limited range of the electromagnetic spectrum avaliable for communication purposes? Also, What are the types of communication data that are stored in transmitted in digital form? It would also be helpful if you could give me some links related to those two questions. Thanks in advance.

Dear Folks, The Fusion stuff I've posted before, but the rest is new A New Manhattan Project for Clean Energy Over the past year many luminaries have made clarion calls for a concerted effort to solve the energy crisis. It is a crisis, with 300 million middle class Chinese determined to attain the unsustainable lifestyle we have sold them. Their thirst for oil is growing at 30% a year, and can do nothing but heat the earth and spark political conflict. We have been heating the earth since the agricultural revolution with the positive result of providing 10,000 years of warm stability. But since the Industrial revolution we have been pushing the biosphere o…

Hi everybody, I was just curious to know why is it that an electric current; the magnetic field it produces, as well as the direction of the force it produces are each at right angles to each other? So far I have just learned this as a fact with things like Fleming's left hand rule but I was curious to know why such a relationship exists.

I'm always confused reading literatures by the notions: electroweak scale, GUT scale and Planck scale. Where do they come from and what do they exactly mean?

Would an anti-matter atom need to have an anti-neutron in it's nucleus? Could it be physically possible to have an atom of anti-matter with matter neutrons in it? For example, anti-helium with two anti-protons and two "standard" neutrons orbited by two positrons?

When you receive a chest X–ray at a hospital, the X–rays pass through a series of parallel ribs in your chest. Do the ribs act as a diffraction grating for the X–rays? Why?

Which nuclear process releases more energy? Fusion usually takes higher pressure and temperature so does it release more energy? I take it fission is more practical for a means of energy since it can be done cheaper.

This topic is an extension to support the theory that there is a fusion core in the center of the earth. The goal is to discuss a fusion approach than can take advantage of the potential created by the earth's fusion core. If look at the earth the most abundant element is oxygen. It is not only a very stable nuclei but it is also the backbone of earth chemistry. The minerals of the crust are oxides and if free oxygen is present, it will react with almost everything on the surface that does not already have oxygen. This very special place in chemistry implies that oxygen should be the goal of fusion, to take advantage of oxygen's stability and its central position wit…

General Relativity + Quantum Mechanics = Error Buy Why? Hi all! I've been reading an interesting book on string theory and I read that one of the reasons it was developed was to resolve the conflicts between merging general relativity and quantum mechanics but my question is what makes these two so incompatible in the first place? My thought on this was that it had to do with relativity dealing with large and exact while quantum mechanics deals with small and probabilistic, in other words they are contradictory in some sence. If that the reason or is it something deeper that blocks their intergration? Cheers, Ryan Jones

Hi can any body help me on this I really need it. The nuclide Sn has a filled proton shell, 50 being on one of the magic nucleon number. Sb has an extra proton outside this shell to make 51. According to the shell model, extra proton should be easier to remove than a proton from the filled shell. Verify this by calculating the required energy in each case. Sn mass 121 Atomic Mass (u) 119.902199 Sb mass 120 Atomic Mass (u) 120.903821 Mass of hydrogen atom is 1.007825u.

Please,can any one give me a good site of packing fraction of an element topic.

I have difficult on finding the numbers of neutrons or protons can occupy the following energy states: (1g), (g 9/2) and (g 7/2).

Can any one explain to me about parity and spin of nuclei or give me the site.example find the parity and spin of Ca with molar mass 47 or Mn molar mass 50.

I want to calculate the density of plutonium,which has molar mass of 244 and atomic number 94.my problem is the volume can I use the standard volume of gas molecule 22.4?

I am doing a presentation on kevlar as a piece of AS coursework for physics. I've been told that I need to explain why the structure of Kevlar makes it a good insulator of heat (I'm saying how Kevlar is used to prevent friction burns in the Skeleton event in the winter olympics). I have googled myself half to death but I cant find anything. Can anyone help? If possible could the answers be kept relatively simple because I need to explain this to people and if I dont understand it myself I cant really impart knowledge. Thanks Anthony

Hi everybody. The thought just recently hit me and I'm sure there is probably a good explanation for this phenomena, but why; when photons are massless particles, do they get sucked into black holes with their strong gravitational field? Is there something fundamaental here which I have not considered?

Recently ive been reading a few things on modern and theoretical physics and it seems that currently one of the most important areas in theoretical physics is to complete or create a theory that unifies all four forces. Obvioulsy it would be an amazing feat if a complete theory was discoverd but what do you think would be the implications of this. Do you think it would give rise to any great technological advances in the near future?

I would like to present something interesting for contemplation. The term center of gravity is a mathematical concept that makes dealing with the gravity between objects easier. But if one looks at the center of gravity of say a sphere, the gravity force vectors will all cancel, such that the center of gravity has no net gravitational force.

I`m familiar with the current type of ion drive we have that uses Xenon gas that get charged etc... if a very large but lightweight and rigid plate where in space and one side covered with a thin layer of some powerfull Alpha emitter isotope, wouldn`t there be a gentle push also on this plate propelling it forwards slowly due to newtonian motion? I only use the Alpha emitter as an example as IIRC, the paticles of alpha are quite large and heavy.

Hello Friends, I'm studying on fluid dynamics and quantum physics for about two years. I realized that there are really interesting similarities between fluids and subatomic particles' behaviours. I have written an article on this subject. I would like to you read my article and take your comment about it. You can read my article from this adress : http://super-fluid-universe.8m.com

I was wondering if anyone could explain the underlying significance of the form of Boltzmann's formulation of Entropy S = k ln (omega) where omega is the number of microstates. Why is it that the entropy increases with the log of omega?