Modern and Theoretical Physics

Where do the four fundamental forces get their energy from? it takes energy to move things, and the forces do it constantly seemingly without an energy source?

I was thinking today about sound and how it is a form of energy. Since the law of conservation of energy States that energy is neither created nor destroyed sound waves should always exist right? Just in different forms or lower frequencies. So in theory isn't it possible that every sound ever made is still bouncing around our atmosphere? And could we potentially "reconstruct" these waves to their original functions? Essentially listening to pre-digital history?

The concept seems silly. Do I lose entropy when I learn something and gain entropy when I forget it? Does something exist if it can't be measured, counted, weighed, timed . . . ? Isn't it a problem of systems and system boundaries? Only someone/some thing outside the system can make the measurement? To say a system has an increase or decrease of entropy one must be outside the system in question. So If I say, "I learned something . . ." am I confusing information and knowledge? Logically, do we consider our minds as some THING existing outside the observable universe? There is an old saying that you don't know something unless you can teach it to someone else…

Hi, I'm stuck for 1 day now about the demonstration of the wave number of a metal by using the Drude model: The equation 4.10 of the book Photonic Crystals Towards Nanoscale Photonic Devices page 122. All what I could get after many checks is : K=w/c*sqrt(1+i*sigma/(w*epsi0)) thanks in advance for your helps guys !!!

You tell me, i have my own theory.

Can a particle have an irrational amount of energy?

second law of thermodynamics states that entropy of a closed system will most probably increase over time. people say you see a vase smashing but never unsmashing. but if i just leave a vase on the work top the probability of it smashing of its own accord is also extremely low. but thats a human example which i think isnt extremely relevant with entropy. water in space freezes and goes into a sort of ordered state of its own accord, and stays there? gas in space will come together to form a star if not a planet, which are pretty oredered, we can be more certain of the arrangement of molecules of a planet than of a nebula. whats the relation between brownian mot…

Only matter is affected by gravity. And if light is made up of matter, why won't it destroy anything it goes through? Would this answer be correct: Black holes warp space-time so much that any particle that crosses the event horizon finds that simply moving forward in time also moves it toward the singularity at the center of the black hole. The only way anything could escape the black hole would be if it could travel faster than light. You can view an event horizon as being defined to be the boundary between an escape velocity that is lower than c and an escape velocity that has to be greater than c. Another question that I can't answer is: Would lig…

From what i understand, the principle states that no two identical fermions can occupy the same quantum state at one time. i have a few of queries: Is there no two electrons in the same quantum state in the whole universe? If two electrons are on either side of the universe, can they be in the same quantum state? Would we not have noticed this? If we try and put an electron into a quantum state, but it some galaxy far far away (pardon the pun ) there is already an electron in that quantum state, would we have trouble putting it into that state? is it not possible? or would it force the other electron out of that state? violating information/speed of light. or is it …

In the ZWM study of early 1991, Mandel (U of Rochester) achieves "induced coherence withouyt induced emmission" between two optically pumped downconversion crystals (figure provided). The explaination of the experiment goes like this: The pump beam goes to the 50/50 beamsplitter (BS) and then pumps one of two downconversion crystals (DC1 and DC2) which transform the photon into two photons (signal and idler) with each having roughly half the frequency/energy. The idler from DC1 is forced to transmit through the DC2 crystal so that it retains coherence between the output of the two crystals. The two signal outputs from DC1 and DC2 are combined at a detector Ds . Ther…

"Loschmidt's paradox, also known as the reversibility paradox, is the objection that it should not be possible to deduce an irreversible process from time-symmetric dynamics. This puts the time reversal symmetry of (almost) all known low-level fundamental physical processes at odds with any attempt to infer from them the second law of thermodynamics which describes the behaviour of macroscopic systems. Both of these are well-accepted principles in physics, with sound observational and theoretical support, yet they seem to be in conflict; hence the paradox. " All physical laws except of the 2nd law of thermodynamics are reversible in time. Which is a paradox, because it …

Hi, if all the energy in the whole universe does not leave the universe & in time (Billions/Trillions) of years when all the black holes join together & go back to the start, like it was at the start of time, The energy that has been "retrieved" is at one point again. Now as I understand it that mixed energy could be in any state until such a time something happens until the " right mix is made" to create another Big Bang which starts off the whole cycle again, If the was the case would not the universe itself be constant energy?? Thanks for any feedback

IS it possible to add or remove a proton from an atom so that it will have the same configuration of another element?

I have been looking at the structure of the atom lately and wondered what makes the electron orbit? You would think if a proton is positively charged and a electron is negatively charged that the two would eventually stick together. I realize in theory that the orbiting electron like a planet never lets this happen. But what makes an electron orbit in the first place and when an electron goes from one atom to another how does it automatically orbit in a way that it does not collide with the proton or neutron? I am not interested in theories (there are way to many of them flying around), but in proof + experiments on what is going on. Thanks.

Was wondering, are topological defects the result of the proposed singularity of the universe having irregularities etc..

Hello everyone, My name is Mir and I am an undergraduate student studying in Brighton, UK. For my ‘Climate Change and Global Business Operations’ module I am conducting a research project regarding ‘Nuclear Fusion technology being a viable concept in the future to provide long-term low carbon energy’. I am writing because my project requires me to conduct primary research to support my secondary research and was wondering if people who have the relevant knowledge would be kind enough to answer a short (6 question) semi-structured questionnaire regarding nuclear fusion (below). If you don't mind, could you please include your name, what you study/teach and the universi…

If you take a large cloud of gas in space (nebula), it has very high entropy. Once it starts to attract itself through gravity, its entropy decreases. When it gets hot enough to form a star, does it have even lower entropy? and at the end of its life cycle does, lets say this particular star turns into a neutron star, neutron stars have extremely low entropy right? so gravity lowers entropy, so why is it proposed that black holes have maximum entropy? it seems to me, even if you took all the possible combinations of particles inside the event horizon, this would still be lower entropy than if all the mass in the form of a star.

Is there a way to compress matter into degenerate matter here on Earth? Would have you to constantly compress it or once you compress it does it just stay like that?

First of all, in beta decay (+ or -) I know it emites an electron/positron and an electron antineutrino/neutrino, however I noticed on some A-level work one of the bosons was involved with the beta decay, I was wondering what role it plays in the decay process... Also my physics teacher said "beta+ decay doesn't occur in nature", and I questioned that thinking about what happens in the sun when two protons fuse and will surely undergo beta+ decay to create deuterium (which would then allow a proton to fuse to make helium-3, or deuterium to make helium-4), I'm sure I'm right in thinking his statement needs reworking?

So I understand that any "change" in a gravitational field could only happen at the speed of light, but in GR, there's no force carrier particles that travel at a finite speed, so does that technically means an interaction between two objects in each other's fields is analogously instantaneous?

In classical mechanics, the flow of electrons through a wire will cause iron filings to align in the direction of the magnetic field which is perpendicular to the flow of the current. Just out of curiosity, has there ever been a similar experiment such that neutrons are fired at high speeds (comparable to electron speeds) down an axis to see if there is any comparable effect? I know the neutron is chargeless so it shouldn't cause any induction, but I'm curious to know if any such experiment has been undertaken. Thanks.

i remember thinking this when i was a kid. so i wanted to ask this question because i think it's still a theoretically stable question that someone with some background in theoretical physics should address. based on our current understanding we cannot travel beyond the speed of light because Einstine said its not possible, as we approach the speed of light our mass would increase and the energy required would also be greater, the only way it could be done is if we had an infinite energy which cant happen. (though, it is said that black holes have an intense enough gravity to pull objects in near the speed of light.) we already established this understanding... my…

Hello all, To start let me say that I have no formal training in theoretical physics, I am simply fascinated by the subject and it has become somewhat of an obsession of thought. I have a general understanding of what string theory is and I do grasp the concept of 10 (or more) dimensions. Now for my question: In my understanding of string theory, the 4th dimension is postulated to be time (correct me if I am wrong). However consider this: A "creature" living in 1 dimensional space would only be able to move "left" and "right" if you will. However in the course of his travels, he could consider that he is now further left or further right than he once was.…

. So if you know math please help me out . . Ok useing 1.500,000 V. at 200,000 A. in a Zpinch on 1 L. of heavy H. and at the same time forceing the plasma inword with a speed of 27,000 FPS and a PSI of 1,500,000 WHAT WOULD THE CORE temp. & pressure be ? will that start fusion ? Please help

Space has always been expanding as long as the universe has been around, also time has always moved forwards as long as the universe has been around. Einstein linked space and time in his view of space-time, maybe the universe expanding and time moving forwards are linked? Gravity causes objects to accelerate, get faster with time, as space-time gets warped. Thoughts?