Quantum Theory

What is the difference between atomic number and atomic mass?

I read this interesting article about time travel, quantum mechanics, and the infamous grandfather paradox: Quantum Time Machine Lets You Travel to the Past Without Fear of Grandfather Paradox This got me thinking: I know that I can't use it to visit the past, but maybe to "view" the past. But I do have one question that is left unanswered. If I build such a device, could I use it to view the past before the device's existence? The reason I ask this is because I know that all time machine models proposed in General Relativity forbid time travel before the creation of the time machine due to the laws of causality. And in this Quantum Mechanics version of "Retroc…

Am reading How to Teach Physics to your Dog by Chad Orzel. Good book on quantum mechanics in layman's terms. It discusses a subtle point on Quantum Entanglement and Bell's Theorum. Orzel says that Bohm's version of quantum mechanics uses nonlocal hidden variables, and reproduces all the predictions of quantum theory using particles with definite positions and velocities. Then Orzel says that Bell's theorum experiments have conclusively shown that quantum mechanics is nonlocal. So far so good. Both standard QM and Bohm's QM are nonlocal. So Bell's theorum experiments show that the universe is nonlocal. But do they say anything about hidden variables? As I underst…

I've always been wondering why gamma rays always seem to act like particles, while radio waves which are also photons act more like waves than particles. So I'm wondering now if the reason is because of the uncertainty principle: The energy in a radio-wavelength photon is more precisely determined (or in general, just smaller) so its position is less determined, while in a gamma ray its energy is less precisely determined (or in general, larger) therefore its position is more precisely determined.

I was just thinking, if you had a 2-D circle sidewards and shown to a three dimensional observing entity, there appears to be nothing there, yet something is there, and maybe the opposite is true. There appears to be something yet there is nothing. And maybe nothing exists. Although it sounds irrational, just open your mind for a minute and maybe nothing exists. Although you may argue "I doubt therefore I am" yet if you wrote the words "I doubt" on a piece of paper, you could then realize the possibility of letting a computer process the words "I doubt" in someway, then maybe our brains can process the words "I doubt" and we can experience an illusion that "I doubt" y…

I know there's the uncertainty principal, but why does matter having a large mass decrease its wave packet size? An electron has very low mass, which is why it can encircle and entire atom as one shell, but a proton has a mass some 1800 times larger than an electron, and its wave is concentrated and a very small reigion. But wait, what about quarks? They are small than an individual proton. Whats the deal?

In the room temperature thermal energy exits as vibration or long length electromagnetic(EM) waves or molecular kinetic energy, etc.. At the high temperature I suppose EM wave energy ratio may be high. Then the highest temperature thermal energy is like this. High UV -----> X ray--------> Gamma ray---->? And the remained energy is stored as quark-gluon plasma state. How shortest wave length EM wave is possible in the real physical world? And the next step? Is the highest cosmic-ray EM wave? For example 1x1020eV.

I don't really know quantum mechanics, so I need your opinion. This guy is relating quantum mechanics to transcendental meditation. Is it possible that what he is saying is valid? (talk about QM finished at about 2:50)

Do you think an atom can exist as information on a quantum field? Perhaps waiting for the conditions to be right for re-assembly? Some kind of, "information packet" similar to the information flying around on the internet? I read in Astronomy magazine that: " in the early processes of the BB that it was to hot for neutrons and protons to exist" (in so many words). So, at some point during the expansion mass was created or assembled. Got me to thinking that there might be a fith state of pro atomic matter.

How to explain Wave function concepts to a High School student with bear knowledge of mathematics

Ok, so they cool this substance so that all atoms occupy the lowest energy state, making them all in the same state, and also really close together. But, is that property caused by entanglement, or that because they are all so close together that all the particles wave functions are entangled, and if so, does that disappear when you observe it, or does it stay there because the waves are still all in the same state and technically interacting with each other at all points in time? Cause I've heard it being described as "you can now see the quantum effects on a macroscopic scale", but that pretty much defies my understanding of quantum mechanics.

I don't know much about QED but I watched some youtube videos on the subject and I have a couple of questions. So far it is my understanding that + & - energy pops up pretty much out of nowhere, in pairs, and quickly anialates itself within the nucleous of an atom. This action vibrates the proton and nuetrons and so on and so on. My question is: Is the nucleous of an atom literally a quantum field? and: Is it possible that this slight electro magnetic eneregy could come from a static electric field caused by the friction from the surface tensions of a "light time dimension of space" and a "quantum time dimension of space" OR, are there any other theories? …

When you observe something, it gets sent to specific places in your brain, but since your not observing or sensing every part of your brain, shouldn't particles be undetermined in your brain? I mean, there's not even any nerve cells directly on your brain.

Let us think about electromagnetic wave. very high temperature-----> UV emission high temperature-----------> visible light emission room temperature ---------> IR emission low temperature------------>micro wave emission?? If not, what is the problem?

So say I have an electron from carbon sharing a bond with Hydrogen. The electron from the carbon atom has enough energy to exist in the second energy level, so what happens to the energy when it fills the shell of the first energy level of the hydrogen atom? How does the cycle continue? Shouldn't the electron lose energy when it goes to the hydrogen atom's first energy state?

What is the shortest time we can measure by using present technology? Which method we can measure it?

A future breakthorugh tech, however way ahead of our time, or not with the way technological advances are progressing, it is projected that we will discover and do more feats this coming century then mankind has done in 1,000 years. Since we are expontentially expanding our knowledge we never know when this stuff might be possible: everything from liquid computer processers to engines that convert light from stars to energy to speeds far greater than 1,000,000 miles per milliseconds, great things are possible, but sadly man will make new laws that limit themselves until new breakthroughs come. My question is how far is a useable technology using particle physics. N…

It has long been known that the center of a black hole is where the rubber meets the road, so to speak, in theoretical physics as it applies to special relativity. However, it's also the place where the rubber goes through the road, stands on it's head, and recites verses, verbatim, from Johnny Depp's diary kept during the filming of Alice in wonderland (affectionately dubbed, the shroom chronicles). The center of a black hole is where, Classical physics, Plane Euclidean Geometry (beautiful Euclidean Geometry as well), Simon Cowell, Neil Young, and Mother Teresa, are as relevant as a commodore 64 . However it makes me want to burn physics books when I see the sharpest…

Without a solid "quantum gravity" theory we seem lost in our quest to find the bridge between the banks of General Relativity and the banks of Quantum mechanics. That bridge is currently under construction and the contractor "String Theory Limited" is trying desperately to prove that the size of the bridge does or does not matter. Well, with what has already happened at CERN and the LHC near Geneva Switzerland, it seems that "Supersymmetry Unlimited" may have emerged as a major subcontractor for the all important bridge construction. Is it possible that they have concrete evidence that the particle with zero mass and 2 units of spin does exist?

I was looking at a feynman diagram to show the decay of a neutron into a proton (by a down quark decaying into an up quark by emitting a W- boson which then decays into an electron and an electron antineutrino). In a nutshell, Beta- decay. Here is the said diagram this article is not questioning beta- decay, but asking about the directions of the arrows on the diagram. As you can see, the electron antineutrino is pointing towards the vertex, whereas the electron is pointing away from it. now this would seem to mean that that the antineutrino is going back in time. this is not the only diagram i've seen that does this. http://images-mediawiki-sites.thefullwiki…

I have, like many, allowed my mind to fantasize of space travel. I would very much like to find this ever sought after tunnel to everywhere that would allow me to see many things strange and new. I guess the concept of traveling a fold in space as a consequence of the ever dense blackhole is simply due process for the mind that inquires about these things. I myself am putting my monies on quantum tunneling and travel through the space time fabric as evanescent modes(of all the impossible propositions.) I hadn't thought of this before but are there any theoretical concepts or whatnot governing the tunneling of a blackhole? I have seen a bit mentioned about quantum …

Let us think about this case. There is a vessel, which contains anti-hydrogen gas. The balance indicates 1g. In this case, can we state minus 1g? Does this have any problem?

If or when you have a couple of hours to spare have a watch of this http://www.youtube.c...h?v=VT50SV3W5K0 I saw it about 3 years ago so can't remember the detail but I'd be interested to hear other people's thoughts

If I set up a double slit experiment the traditional way, with an electron gun shooting one at a time through a double slitted wall, BUT, I but a person who's BACK was facing the electron gun in between the last wall and the double slit wall, how would that effect the superposition of the electrons getting shot? Would it be like this? or this? Or this?

I'm currently trying to learn quantum theory but although i get it somewhat, it still confuses me a lot. What are some books i can read to help improve my understanding of quantum theory? (I'm reading "The Complete Idiot's Guide to String Theory" and the part explaining Quantum Theory was rather confusing)