Modern and Theoretical Physics

Planck units like the mass and length come up all over the place in modern physics---they are not the only system, there are other convenient special purpose units, but they are worth getting familiar with. Using the google calculator we can take a kind of almost experimental approach to planck units, explore, build up our concepts, try them out. It is easy---a few posts will show what I mean. So here's a brief tutorial. 1. get to know hbar (Planck's constant) Think of hbar as being the product of amounts of energy and time. Check that by typing things like this into google hbar/minute hbar/year It will give you answers in energy terms----small amounts …

I was wondering if the heat generated by eddy currents (in a theoretical experiment where a wide range of materials were tested) could be measured using an apparatus similar to an induction furnace. I have attached a diagram along with this post to show u what i mean. I was going to measure the heat generated by each metal through a thermometer in water. The water will absorb the heat generated. Can u see any potential weaknesses in this attempt? Will the water always heat up to an excess of 100 degrees? If so, can this be controlled by lowering the voltages applied? (Plz ignore any heat lost to the surroundings.) Thanks for ur help! Prac Diagram.doc

I heard off a mate yesterday that the lowest temp pos is -275'C which is absolute Zero. It is not posable to reach this temp due to the fact that to contain somthing 100%, is imposable as any contained substance will in fact be touching the sides of the container, thus energy will be flowing in to the target. is there anyway of knowing just what would happen to anyitem, if all the engergy was removed by reaching -275'C... and would the same thing happen as when you burn something? let me know, im intrested to hear more on absO.

When I read, "the universe was at an age of 300,000 years" in a post in another thread, I wondered how could anyone determine that number. Well, one might think an age was determined and then it was expressed in terms of years--so that the reader could understand. And how would someone determine that particular duration? What is the basis for any expression of duration. Anybody? Time is linear, memory is a stranger, history is for fools.... Roger Waters, Perfect Sense, Part I from Amused To Death

Okay so time is a dimension of the universe according to current modern theories and it is mathematically valid. Following this math, time and space are one and the same entity at the beginning of the universe. If time and space are one, what does this mean for a universe that is both expanding and progressing through time? Also, what does this mean for the specific inception of the universe? What I mean is, if time and space are one, what does "before" and "after" mean in that context? How does that relate to the "birth" of the universe and what we would call the following moments that include time and space being one? If, when moving back towards the beginning, time and…

Can a computer program be made that fully and accurately simulates an electron?

Hi all, I'm not even sure this is the right place to put this thread, I was guessing according to the subject, sorry if I got it wrong, feel free to .. uhm.. relocate me.. I was watching (Again!) The movie "What the @$&^%^#!@ do we know" and there was something there that got me wondering about one of the things said there in particular. In the movie, they showed an experiment done with water and different "moods" -- blessings, curses, words written on pages and such. The water looked different in the microscope in each different canister, even though their initial state was exactly the same. Can that be possible? Is that a working experiment, or just …

From QM, the binding energy of electrons onto protons is ("Rydberg energy"): [math]U = \frac{1}{2} \left( m_e c^2 \right) \alpha^2[/math] and the radius of those bound electrons is ("Bohr radius"): [math]R = \frac{\hbar c}{m_e c^2} \frac{1}{\alpha}[/math] So, if the EM interaction were "full strength" ([math]\alpha \rightarrow 1[/math]), as the Strong interaction between quarks in nucleons (nearly) is, i.e. "if (virtual) photons were as strong as gluons"; then (hydrogen) atoms would be ~137x smaller (10-12m), and their binding energies would be hundreds of KeV. Now, nuclear interactions are characteristically MeV in strength. So, an "un-fine-tuned" EM …

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 …

The journal "Nature" invitesto discussion of Leonov's theories – the theory of Superunification. http://www.nature.co...10.1038/471006a TheSuperunification theory is the most powerful analytical means of investigatingmatter. The theory combines the theory of relativity and quantum theory andrepresents a new stage in the development of quantum theory. It has been proventhat the principle of relativity is the fundamental property of quantisedspace-time.

The "OZI Rule" states that any process, which is "mediated in the middle" (my words) entirely by Gluons, is suppressed. Does that mean, that "Glue-balls" would also probably be suppressed ? David Griffiths. Introduction to Elementary Particle Physics, pg. 83. ("Suppressed" does not mean "Forbidden".)

From wikipedia: I was just wondering if this really has any scientific merit....

Where I can find precisely calculated values of oxygen quadrupole moment & its derivatives (or "quadrupole polarizability")?

I think it would be great if people would throw into a common pot what new papers they find most interesting. This thread could work that way if D H wants. It already has kind of a cute title for such a thread and it is already started. So I would think serendipitous if DH says OK and we just keep going! How about that DH? Your call, either way is fine.

I read this YouTube comment this morning from user Aural Escape on Anton Petrov's 'Was there something before the big bang' video he released Aug 16th. Got me thinking of ways to see beyond the edge of the visible universe and I thought I might have a way you could in theory cheat and know what galaxies there may be beyond the edge of the visible universe. Imagine a far future where we can travel at or near the speed of light. We travel to the edge of our galaxy or even into Andromeda. There we meet and share information with an ET civilization that has been doing astronomy for X billion years and keeping records all that time. Those ancient records would effe…

An interesting paper as appeared on the arXiv under "popular physics". "So what will you do if string theory is wrong?" Authors: Moataz H. Emam Emam argues that even if string theory is one day shown not be a model of nature, then it will survive somewhere in between physics and mathematics. It will be too much like maths for the physicists and too much like physics for the mathematicians. There are just too many nice mathematical results to simply throw string theory away. On the physics side, there may well be one saving point. The AdS/CFT correspondence allows us to identify perturbative but non-physical string theories with perturbative, but (possibly) …

Without, yet, so much as a single experiment to prove (or, disprove) the existence of "strings", how have "strings" speculations graduated, from "hypothesis", all the way to "theory" (i.e., why is the model not called the "strings hypothesis") ? Scientific Method

Hey, Over the past six years I have worked with Lucien Hardy at Perimeter in Waterloo and Prakash Panangaden at McGill. This paper is the culmination of thoughts on physics gleaned from that work. On Introducing into the Foundations of Physics the Notions of "The Probing of, Approximation to and Idealization of Structure" or try this link On Introducing into the Foundations of Physics the Notions of "The Probing of, Approximation to and Idealization of Structure" or this link On Introducing into the Foundations of Physics the Notions of "The Probing of, Approximation to and Idealization of Structure" Preamble: After completing the requirements…

Is it possible to move matter at 1/2 the speed of light given earth's resources? And if so, would it not create a 1/2 matter 1/2 engery occurance which's size and strength would be determined by the size of the matter moving?

Hi, in classical physics, in a closed system energy is conserved for every instant of time. But in quantum physics, quantum fluctuations (very short particle/energy creation or annihilation) on microscopic level can occur. But both theories have the same propertiy that the Noether theorem holds: If the theory is invariant under time translations the energy is conserved. In every quantum field theory there is time translation invariance. But are there theories that are time dependent (i.e. theories that break homogenity in time)? Why, the homogenity in time and homogenity in space are the most essential symmetries in physics (of course there are theories that viol…

I know 1 atom of uranium-238 isn't critical mass, but theoretically, if you could split 1 atom of uranium-238, how much energy would be produced? ~ee

In boosted fission and fusion bombs what is the ratio of deuterium to tritium?

In Quantum Field Theory we calculate the matrix elements which give the probability that an initial state |i> will turn into a final state |f>, e.g. |i> could be an electron and a positron, and |f> could be two photons. I don't really understand why this works the way it's done. The interaction process is meant to be a collision: the initial particles start off far away from each other so they don't interact, then come together briefly and react to produce the final result; the resultant particles move apart again. It's a scattering process. So why do we look at the matrix elements for states which have definite momentum? These are spread all over spac…

Hi, My first post outside of the 'intro thread' -- not entirely sure this is the correct sub-forum. Question: Are the properties of Infinite Mass exactly the same as the properties of an absolute vacuum? That is: the same everywhere, one state, no events, no time, no temperature, ... what else? I asked this question in '92 and got a 'yes' but, I'm behind the curve and out of date now. Thanks! Ron

Just wandering if anyone has identified any if not all the 11 dimensions and if the following has been thought of or makes any sense. Height Width Depth Time Supertime Magnetism " electricity" Counter space or dielectric Matter Anti matter Space Hyperspace And could that not only be the start, the Vedas describe 64 dimensions with a bunch of sub dimensions