Macroscopic Definition and 126 Threads

This question is in the book " Introduction to nuclear engineering by Lamarsh" Chapter3: I think it's pretty basic but I couldn't find the proper way to prove it, and now I even suspect that it's not a correct question. My attempt solution: I would very much appreciate your help. Thanks in...

In the headline to the question the statement should have been: rotation of macroscopic magnetization = averege (Magnetization current density ) The Magnetization current densities ##\vec{j}_{\text{mag}}^{(i)}## of individual particles ##i## are stationary ##(\vec{\nabla} \cdot...

Isn't the quantum tunneling probability of macroscopic objects always zero due to quantum decoherence? It may be possible in the microscopic world, but I always think it is impossible in the macroscopic world due to countless interactions. Isn't this the same in a universe with infinite time...

One of the strange features of Quantum Mechanics is that for his formulation one needs the classical physics that actually should emerge as its macroscopic limit. All experiences with quantum objects have to be analyzed through classical "glasses". Naturally, then the question arises: where...

Of the classical books about EM, I found that Jackson's is the only one that touches with some rigour the subject of deriving the macroscopic field from the microscopic one. Unfortunately, I am quite disappointed by the derivation of Jackson. In the reference he gives, he says that a couple of...

Very confused about this article and the experiment it's based on. I'm not very knowledgeable on this, but I'm very confused on what's happening here. It seems extremely weird to me

This paper suggests that macroscopic dark matter could leave a trail of ionized plasma as it passes through the Earth's atmosphere. If this happens during a thunderstorm it could trigger a lightning strike that follows that trail. https://journals.aps.org/prd/abstract/10.1103/PhysRevD.103.063024...

If we prepare a macroscopic system (something like Shrodinger's cat) in a known quantum-mechanical state and we let it evolve for a very long time completely isolated, for what I understand the position of all it's particles will become more and more spread in space. But if the evolution of the...

In biology and optics, macroscopic and microscopic are distinguished by being large enough (or not) to be seen by the unaided eye (or almost), vs. requiring a microscope rather than just a hand lens (or macrolense). Fairly small things (like paramecia) can be easily seen without a microscope...

In classical probability theory, a probability space has a set of "point" or "outcomes" which may be multidimensional vectors. "Events" are sets of these points. By analogy, in QM, it seems a macroscopic event would defined (in principle and mathematically) by as a set of possible...

When I think of a wave propagating through space I think of a geometric wave-like structure propagating through the matter in the surrounding environment. If someone yells and you hear their voice is it actual matter that is emitted and that your ears pick up on? If this were the case there...

Quantum Mechanics seems to explain phenomenon happening on a microscopic scale, where measurements aren't definite and probability plays a role. Classical physics explain macroscopic phenomenon where measurements are definitive without probability of that event happening. Is it happening just...

The question bothering me is when does an object become classical? I believe the answer is actually never. The summary is perhaps a better way to frame my question.

A composite object made of many atoms has a large mass hence a small de Broglie wavethength...and we know that recent experiments succeeded to obtain interference patterns even for such objects (for instance the C60 molecule). Did theoretician understood how a wavefunction with such a small...

Hello, I am currently working through Liebermans textbook on plasma physics. The book starts by simply stating the Maxwell equations, which are used heavily throughout the book. The Maxwell Ampere law however is written in a form that I have never seen before and I am not sure is correct. They...

From here: From here: Peres writes on p.11: And on p.58: Note that Peres says that these issues are not yet fully understood! On p.63, Peres writes: On p.424: And on the next page: The footnote quoted by Peres says: And on p.25, where Peres introduces ensembles, he says (like Gibbs...

My textbook explained that it would be hard to see the wavelength properties of a tennis ball because we would have to find a very tiny slit in which to pass the tennis ball through. The wavelength of the tennis ball can be calculated using debroglie formula: wavelength = h/p I was wondering if...

In a discussion between Sam Harris and Brian Greene, at this point, Brian stated that even if we return the brain and all the environment to its previous state, we "WON'T MAKE THE SAME NOISES"; I know that for example, indeterminacy in determining the precise time of decay of an atom (and the...

Homework Statement Hi everyone! My name is Alexandra, and I'm new in this forum. I am trying to determine the mentionated tensor without the assumption of linear media or vacuum ( ## \textbf{D} = \epsilon \textbf{E} ## and ## \textbf{B} = \mu \textbf{H} ##). What I want to obtain is the...

Hi, If the microscopic world is not deterministic, then naturally the macroscopic world should also be not deterministic because it is based on the microscopic world. The problem is that the macroscopic world is deterministic; the evidence of this is that a lot of our technology and...

Hello, is everything binary on macroscopic level ? I know on quantum level there are multiple states, instead of binary. I can't find any studies, it seems like everything is binary on macro level, light-dark, death-life... So what would be opposite of iron, or wood, for example ? I can't think...

Hi all. I'm trying to understand (QM) spin. I have plenty of questions but this one is quite simple. Lets say there is a tiny grain of coal (because it's black), far away from gravitational or EM fields. I take a laser, and pick photons that have spin +1 in the z-direction, it doesn't really...

If we consider the Unitary evolution of the wavefunction, and interpret measurements as becoming in superposition, taking it that the measurement device gets in a superposition of spin up and spin down, do two measurement devices that each measure one particle of an entangled pair become...

There's enough angular momentum in electron spin to get a 1cm radius ring of silver atoms to turn with a period of order days after relaxing from spin-up into randomness. (assuming you could get all of it to show up externally, and not end up in microscopic rotations or l quantum numbers.) I...

So I followed the derivation of the Macroscopic Maxwell's equations by averaging the fields / equations and doing a taylor series to separate the induced charges and currents from the free ones. But why does light now "suddenly" travel slower in dielectric media? I mean, sure, it comes out from...

Hello In nuclear physics, the mass excess is caused by the nuclear binding energy. Question: is there any macroscopic example where the "mass excess" is non-negligible? Thank you for your time. Regards.

School physics has always taught us that the big difference between a magnetised object and an electrostatically charged object is that the latter has on it an isolated positive or negative charge whereas the former cannot be an isolated N or S pole, ie. you cannot have a magnetic monopole on a...

Is it correct to consider a given macroscopic object as a continuum arrangement of harmonic oscillators, each composed of a point mass? Would the error in such a consideration be too large?

I was just wondering if macroscopic things like a book or even a human can travel to another universe, like quantum particles.

Hello all, Jackson Ch. 6 (3rd edition) tells the reader to look at de Groot for a statistical mechanical derivation of the macroscopic Maxwell equations. I figure he means "Foundations of Electrodynamics" by S. R. de Groot. I requested that book be sent to my school library on loan, but I was...

I know the key tenants of quantum mechanics, and am not interested in the measurement problem. What we do know is that a particle has a wave function that describes the likelihoods of it having certain EXACT values when we measure it. That's all good, but I am still confused how the classical...

Homework Statement Hi everybody! I have trouble understanding the following problem, hopefully somebody can help! Show that the electrostatic potential ##\phi(\vec{x}) = \phi_\text{free} (\vec{x}) + \phi_\text{ind} (\vec{x}) = \frac{1}{4 \pi \epsilon_0} \bigg( \int d^3 x'\...

I was just wondering if the quantum Zeno effect can be applied to macroscopic systems. It's applies to microscopic systems such as atoms but how about macroscopic systems like the universe?

This thread is to serve as both a compilation and ground of discussion of key experiments, both historical and planned, which attempt to probe possible macroscopic limits of QM, taking into account e.g. some particular gravitational/optical/mechanical/superconducting/etc aspect and/or...

Bhobba said "Decoherence usually requires interaction with something macroscopic and an environment". I assume decoherence still occur to the atoms and molecules inside any object because they are exposed to the thermal vibrations and CMBR. Let's say for sake of discussion we can freeze an...

There is one thing that I don't understand when considering quantum mechanics for macroscopic bodies. It is said that classical mechanics is a valid approximation and that macroscopic bodies that we encounter on everyday basis have a small uncertainty in position and momentum. So far, so good...

Has teleportation ever been able to teleport the information of an entire atom? I feel like I've only seen electrons being teleported (with changes in spin being measured) and it makes me wonder how the teleportation of something like an apple would work. It seems like you would need to have all...

I have read the description of electrons as standing waves based on an analogy with a string vibrating at its natural frequencies: thus the different quantum levels are akin to the tones or harmonics of the string, right? So far, so good, but then I have seen contradictory complementary views...

I have a long-standing question regarding the fundamental nature of macroscopic QM in combination with MWI. First, generally speaking, what does the Born rule say about macroscopic objects and experiments (without superfluids and other traditional examples of quantum behavior on the large...

Consider an object of mass 1kg moving with a speed of 1m/s. Theoretically , the de broglie wavelength associated with it is about 3.6x10-37. Now if we calculate the energy associated with this wave it comes out to be 3x1011. This is a huge amount of energy which could be very hazardous but it is...

Radioactive decay is known to be a pure quantum effect, the particle from the nucleus is in a superposition until we measure it (according to collapse interpretations). In the Sch. cat experiment the radioactive particle gets entangled with a macroscopic object (Geiger counter) and so the...

Hello. I read a lot about Casimir Effect. It creates attractive (or repulsive)force between two metal, parallel, electrically neutral, conducting plates. It causes that between plates, it is less electromagnetic field fluctuation wavelength than outside (vacuum). Logic tells me that if vacuum...

I've seen a couple of lectures by Penrose where he describes an experiment to test superposition of physical location of a very small, but macroscopic object. I can't find a reference to it online, but the experiment involved sending a photon through a half-mirror, and depending on the route...

Breakthrough Starshot is an ambitious project that aims to use a superlaser to push a tiny craft up to 0.2 c https://en.wikipedia.org/wiki/Breakthrough_Starshot At such speeds, it would be possible to perform a macroscopic test of the longitudinal acceleration, provided the craft has an...

Hi guys, I saw mr. Nugatory's post on one of the older threads which got me a bit conceptually confused so I wanted to ask you a question regarding it. This is the original quote: "For most macroscopic systems most of the time, the wave function evolves in a way that makes quantum effects like...

I came across an quote from a physicist so I wanted your opinion. Most physicists, Walmsley says, believe that quantum entanglement is a property present in all objects in our macro world; we just don't see it happening. "In the everyday environment, objects are connected to other objects," he...

Homework Statement To what velocity would an electron (neutron) have to be slowed down, if its wavelength is to be I meter? Are matter waves of macroscopic dimensions a real possibility? 2. Homework Equations I have assumed this could apply to pretty much any free particle of mass m, and is...

what will be the scenario if Heisenberg's uncertainty principle is applied at macroscopic level?

What is enthalpy of a system based on macroscopic POV of thermodynamics and not chemistry? And how do we use it to calculate the total heat transfer in isentropic processes?

scientists have observed light acting as waves on a macroscopic scale before the quantum characteristics of particles were discovered. My question is what sets apart the macroscopic wavelike characteristcs of light apart from other matter waves? This may be a stupid question but can the...