What is Macroscopic: Definition and 125 Discussions

I suppose a related question is in regard to the fundamental nature of quantum superposition. Does any system in superposition "necessarily" demonstrate interference on a macroscopic scale?

Max Tegmark in his paper “Many worlds in context” http://arxiv.org/abs/0905.2182 Argues that …. .“Everett’s MWI is simply standard QM with the collapse postulate removed, so that the Schrödinger equation holds without exception”. He also argues that from this we can deduce that not only...

Is reality mind-dependent ? I saw a lot of videos on internet arguing that the 'holographic theory' proves that our world is an illusion created by our brains.. and every person has their own individual world in his brain...just like a movie, they use QM as a proof, and Tom Campbell as a...

Hi fellow PFers, long time reader here. I have a query that was motivated by a comment on another thread (“Decoherence question”). It is about the quantum properties of decohered macroscopic systems. In my (incomplete and perhaps misapprehended) understanding, a macroscopic object, say a chair...

How much energy would be required to accelerate something the size of the space station to the same speed as protons colliding at the LHC?

Greetings to everyone. I would like to ask how the shape of a rocket exhaust plume changes with distance, when the rocket operates in a vacuum. What I'm mainly looking for, is to see how large the diametre of the plume would be at a distance of ~20km from the nozzle. We're assuming an ordinary...

Suppose we have a small object with a planar surface and we can make that object/surface vibrate at an amplitude and frequency representative of the 'wriggling' of atoms/molecules at the atomic level. Will we feel heat if we then touch the planar surface? Can heat be sensed from a macroscopic...

a question which is bugging me... Yes, I know that parity is violated only by the Weak Interaction, which is very short range. So I would answer "no, there is no P violation on macroscopic scale" However, many macroscopic properties are the results of what happens on the microscopic level. So...

My question will probably be enough to make this obvious, but I should start by saying that I have not formally studied quantum mechanics, and I know little more about it than the wave equation as a function of x and t. Does the inherently probabilistic nature of quantum mechanics have some...

Does anyone know of a class or a textbook or anywhere to start doing research on how to start off with a set of desired properties of a material and begin designing that material from a molecular level. A for instance would be say you want a material that is capable to separating oxygen from...

I have been noticing a few examples of systems that can extract energy or do useful work from seemingly random vibration, and I can't figure out why this is. If you take a guitar and smack its body, the strings will ring out to some extent. From a spectral point of view, the delta function...

I wondered if anyone had a good online reference on the covariant formulation of Maxwell's macroscopic equations and the other equations of classical electromagnetism? The wikipedia article talks about constituitive equations in vacuum, which doesn't make a lot of sense to me since M and P...

I'm sure we've all envisioned bombs made by allowing macroscopic quantities of antimatter to react with ambient matter thereby releasing vast quantities of energy in very short time scales. I'm wondering how realistic this actually is. Suppose I have a 1 kg chunk of anti-iron in the middle of...

How is see by our senses a superposition of sensorially distinghible states in superposition, for example, superpositions of states with the same object with a separation of ≈1 cm??

Consider a macroscopic Bose-Einstein condensate. Are there experimental results regarding the propagation (in space and time) of the collapse of this state caused by a point-like perturbation?

Are macroscopic objects "self-collapsing"? For fun (and classroom demos) we we regularly calculate the diffraction and time evolution dispersion of macroscopic things like viruses, bullets, and elephants. But it would seem to me that this is actually a pretty misleading. Anything larger than a...

I have been reading: http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780199560561.001.0001/acprof-9780199560561-chapter-20 It appears Pilot wave theories have no way to explain macroscopic superpostion. Any thoughts or opinons on this?

When do macroscopic properties of matter come into picture? When we consider 2 atoms, 20 atoms, 200 atoms or 200000000000… atoms? I hope I have conveyed my meaning?

Hello, I'm reading a book "How to teach quantum physics to your dog" from Chad Orzel, which is of great fun. Recently I become interested in quanntum Zeno effect. I can't understand why we can't see the quantum Zeno effect in daily life. Below is what I posted on my facebook, and my friend's...

Is there still hope for a rational quantum mechanics? Double slit: Particle in a box:

http://www.technologyreview.com/view/507531/first-teleportation-from-one-macroscopic-object-to-another/ Does anyone know how big that ensemble of rubidium atoms is? Let me make sure I understand quantum teleportation correctly, I probably don't. Some scientists entangle two rubidium...

I am aware and well read on the decoherence approach to understanding how conglomerations of micro quantum systems will tend to lose quantum coherence via interaction with the environment. The cross terms in the density matrix for the system will tend to zero (due to the partial trace...

can wave particle duality be viewed at macroscopic scale...?? ok so far we have discussed the wave particle duality in case of electrons of-course at microscopic level through the 1) interference phenomenon showing its wave behavior 2)photoelectric effect discussing its particle...

i have gone through that photon is force carrier of em force..but in macroscopic level as far as I studied I know em force is designated with field in macroscopic rather than a particle like interaction.so how can they justify that em force is managed by photon.If photon is more plausible is it...

I know Dirac had said yes to existence of microscopic monopole by quantum theory, so why not the macroscopic monopole?

1. Homework Statement The figure shows 1.0*10^-6 m diameter dust particles in a vacuum chamber. The dust particles are released from rest above a 1.0*10^-6 m diameter hole, fall through the hole (there's just barely room for the particles to go through), and land on a detector at distance d...

By 'Genuine Decoherence' - I mean collapse of the wave function by a theory and its mathematical equations. If a micro system encounters a macroscopic apparatus - in collapse theories a definite state appears for both the apparatus and system, but after a tiny time since the system entangled...

I was doing a question while back about finding the de Broglie wavelength of a bullet with a given mass traveling at a given speed- easy stuff. However, when the result was very similar but slightly larger than the Planck length which I'd stumbled across on my few jaunts through Wikipedia, it...

It doesn't have to be a superfluid or silicon oil. Let's suppose a water droplets are falling to a hidrophobic (wd40 sprayed LOL) surface with double slits. It seems probable to me that scenario will happen that droplet will split on surface, pass through both slits (in some random ratio) and...

Hi all, The way I understand it is that temperature is a measure of the random kinetic of molecules and atoms. When you heat something up, eventually it will start to emit visible light once it gets hot enough. When a macroscopic object is moving through a vacuum however, why does it not...

does not occur because the probabilities are of the magnitude of exp[ -1 / h ], give or take a few decimal places, correct? i.e. 1 / some number with > 10^30 zeros after it (trying to explain this simply to my daughter)

So I feel like this should be a simpler problem than most with COMSOL... I have a simple cantilever (anchored at one end) with a force at some point source which is making it vibrate at some frequency. This is a macroscopic cantilever, so you can ignore viscosity (and most of the other Navier...

Looking for a rough distance scale over which statistical methods begin to work, and macroscopic thermodynamic variables begin to make sense. Thanks

Consider this experiment... A satellite is put into orbit around Mars and the date of the experiment is set for when Mars is directly opposite the sun from earth. This puts it about 21 light minutes away from earth. Assuming there are no aliens watching it is absolutely impossible for any...

http://www.physorg.com/news/2011-08-entanglement-macroscopic-dissipation.html http://prl.aps.org/abstract/PRL/v107/i8/e080503 2.2cm cube (1 x 10E12) atoms entangled 0.5m apart for an hour now that's progress!

I've started a couple of threads about this topic before, but those were a while ago, and I still have some nagging questions. 1.) If we wanted to quantum teleport something macroscopic, would scanning come into play? I thought that the whole point of QT was that you don't have to scan...

Okay, I will preface this by saying that I have no formal education in physics. I am just a regular man with an active mind and healthy dose of curiosity. There may be some errors in my terminology, but hopefully you'll get what I am saying. Heck, maybe this is already a well known hypothesis...

I thought quantum entanglement only occur in very isolated environment and laboratory setup. How come photosynthesis use it? Do you know of a website that illustrates how this work in very clear manner? All those paper about the photosynthesis effect are difficult as they are mainly for...

Homework Statement Derive a microscopic version of the continuity equation given \rho(\vec{r},t) = \sum_{i=1}^N \delta(\vec{r}-\vec{q}_i(t)) and \rho is dynamic variablesHomework Equations I wonder if someone can point out the difference (in general) between the macroscopic and microscopic...

What does infinitesimal change in V mean? Can someone please illustrate with simple example. Lecture notes say infinitesimal change in V = dV And large change in V is delta V.. I don't understand what it means though

Has anyone performed experiments regarding macroscopic quantum coherence (superposition of and macroscopic object)? What about testing if macroscopic objects obey macrorealism, or whether QM prevails? Links to articles or experiments would be apprecited.

1) Macroscopic objects have their own wavefunction, right? Would this wavefunction include physical attributes that would contain possibilities for certain features that macroscopic objects have (say the macroscopic object is a bed – the wavefunction would have possibilities for all the...

I have just found out that Feynman also (re)discovered (some essential aspects of) Bohmian mechanics a long time ago, in his "Feynman Lectures on Physics" part III. Namely, in the last chapter devoted to superconductivity as macroscopic manifestation of quantum mechanics, he derives equations...

Hello there folks. So I'm doing some homework, and one of the questions asks for a comparison of the microscopic absorption cross sections of B, Cd, Gd, and Hf with the fission cross section of U-235. I've found the fission cross section in my trusty 17th edition of Nuclides and Isotopes, but...

Homework Statement Consider two macroscopic containers separated by an insulating wall, which however has a circular hole of a few nanometers radius and negligible thickness. The containers (1 and 2) enclose aqueous solutions of a polymeric chain molecules (e.g. a DNA or protein). These often...

From my understanding decoherence occurs whenever a quantum object interacts with a macroscopic sized object. So for instance a measurement involving a photographic plate registering a particle will cause decoherence of the wavefunction, which appears to us as the wavefunction collapsing...

Hi, just a thought but if two elementary particles are traveling parallel to one another at the speed of light does particle a observe the gravitational wave from particle b and vice versa as they would in Newtonian gravitation? i realize that gravity at this scale is negligible. Mark

On 8/16/09 a alxm wrote... Macroscopic objects have a quite definite location, and do not tunnel to any appreciable extent. Another way to say it is: The location of a macroscopic object is only a little bit random, and the probability of tunneling is very very small. Is that correct...

Homework Statement The following describes a method used to measure the specific heat ratio "gamma" of a gas. The gas, assumed ideal, is confined within a vertical cylindrical container and supports a freely moving piston of mass m. The piston and cylinder both same the same cross-sectional...

My first thread here. Please bear with my lack of knowledge. I talked to a physics grad student about whether it's fair to describe QM as a theory applied only to microscopic objects. Although the definition of "fair" is ambiguous, at least he told me that, from his understanding, he wouldn't...