Nature Definition and 712 Threads

In Resnick/Halliday, they describe how rolling can be described as the sum of a rotational force centered at the center of mass (for a wheel, say) and translational motion. The next part involves them saying that the motion can also be described as a completely rotational motion centered at the...

Edit: Here is the short (but more confusing and less rigorous) version of what I wrote below: For something to be considered a "law" it needs to make predictions which can then be tested, and if they are proven then it is considered law. However, scientists have been looking at the nature of...

In lieu of my previous question, (https://www.physicsforums.com/showthread.php?t=494393), which seemed a bit tricky to answer (!), I will simply ask the deeper physical question that lies at its base. That questions is whether there are any physical phenomena (temperature, pressure...

Are mesons and baryons,other than protons and neutrons,observed in nature?where? what about leptons,other than electrons,positrons and neutrinos? thanks

Homework Statement What are the constituents of TNT? How much explosive is it? 2. The attempt at a solution Nitric acid, Sulphuric acid and toluin are the constituents of TNT. I couldn't answer the next question. I would like to know more about its explosive nature.

In the context of all the very latest theories of: The expansion of the universe, The effects of dark matter and energy, Gravitation and the other fundermental forces of nature, General and Special Relativity, Black hole singularities, Inflation, The size of the whole universe and...

First, in regard to this article: http://physicsworld.com/cws/article/news/45535 (http://www.nature.com/nature/journal/v471/n7339/full/nature09778.html) Does the Heisenberg limit apply to single particle systems, rather than N amount of particles? I draw that conclusion from The second...

Lee Smolin stated in Trouble with Physics (page 256): "More and more, I have the feeling that quantum theory and general relativity are both deeply wrong about the nature of time. It is not enough to combine them." <snip> "We have to find a way to unfreeze time - to represent time...

I have a challenging question about electromagnetics. I presume if two antennas were designed to broadcast the same signal, but were designed somehow be exactly phase shifted by 180 degrees. And the antennas were stationed very close together. So that no electromagentic noise would be detected...

The job of a physicist is to study nature, but how many actually get out and experience nature? It seems that the more professional someone becomes, the less interested they are in actually enjoying the things they study - it all becomes about data and graphs and lab work. How many...

Hi, I am in my sophomore year and taking a class of intro modern physics.. I read Methuen's Monographs on Physical Subjects - The Special Theory of Relativity by Herbert Dingle..as a reference The author claims several times that the limit of possible velocities, even in vacuum, the speed...

Hello, I could give many arguments supporting the electromagnetic nature of light. The whole net of modern physics can be used for that, specially atomic physics. However, I wonder what could be the best evidences like: - the oldest - the simplest - the most convincing - the...

Hello all, I'm an uneducated layman (physically and mathematically uneducated) new to the forum and to the whole concept of quantum physics, so apologies in advance if I sound stupid! :P I was listening to a talk recently where the speaker was trying to explain how small an atom was, he was...

Hey guys, newbie here! I stumbled upon your forum while searching for an explanation i was looking for in regards to some theories/questions i have about the shape, structure, and nature of the universe... so here goes! I have some fundamental issues/differences in opinion regarding the...

My question stems from the visual perception of color. First I'd like to clarify what we're seeing. When we see that a material is a certain color does this mean that it's constitute atoms are continuously absorbing certain wave lengths/energy levels of light and blocking out/bouncing the left...

Hi all, I remember in the Elegant Universe (the documentary), at some point the following lines were said: "So what exactly, in nature, sets the values of these 20 constants so precisely? Well the answer could be the extra dimensions in string theory. That is, the tiny, curled up...

The fundamental question about the nature of inertial mass is not solved up to now. Success of Newton's conception of physical force influencing on a separated body may be explained by the fact that the \emph{geometric counterpart to the force - acceleration in some inertial frame} was found...

Do any waves other than EMR show Particle Behavior in nature (Like Sound Waves or Water Waves etc)? In Photo Electric Effect We have considered that the light as packets of energy? but it's equation of energy is \hbar \omega (h bar*omega) and this\omega is the angular frequency of wave. I...

Hey, wondered, what font is used in the title 'nature', on the front page of the magazine? Thank you in advance, Mikkel

We consider an spacelike infinitesimal separation {ds}^{2}<0 ds=+ or -ib [an imaginary quantity] Now I integrate ds along some path from A to B. What happens if the imaginary parts cancel out on integration[if we can manage to cancel them out]?I mean, is it physically significant in any way...

Hello, I had read about the dual nature of electrons and the quantum numbers for some time ago and was always confused. 1-What does dual nature of electron mean? Does it mean that the electron moves in a sort of wave like motion around the nucleus? Where do the sub-shells and orbitals fit in...

I just read another post on this website about torque and the reason for its definition as the product of the perpendicular distance of the point of application of the force from the axis of rotation and the force itself ( ignoring the vector properties of the above quantities). The explanation...

Homework Statement What happens when gas is heated? Is all of the absorbed energy converted to kinetic energy? or is some of the absorbed energy converted into potential and some into kinetic energy? Homework Equations The Attempt at a Solution My teacher said the correct answer...

What does everyone think about this? http://www.fordham.edu/academics/programs_at_fordham_/mathematics_departme/what_math/index.asp

As I understand evolution, with natural selection, nature kills the weakest, for an example predators killing the slowest in a herd of Antilopes. What I don't understand is how life could have evolved into something as complex as us in only 2.5 billion years. I've heard of epigenetics, but that...

has been running for the longest time, i thought maybe a hydroelectric dam

I had ferrets long before they became "trendy" which thankfully waned quickly since most people have no idea how to properly take care of them. My wife and I became an unofficial ferret rescue, and we found homes for many of those cute little weasels. When I saw the trailer for the wolverine...

Hello all, I am writing an article on symmetry in the living vs. non-living worlds, and I am looking for inorganic/non-biological examples of asymmetrical structures or relations at the molecular level and higher, similar to the kinds seen in biological systems. For example: The natural...

Hello, I'm adding one or two words in bold in front of each question so you can browse for questions that interest you, please don't get turned off by the amount of text, I'll be very grateful even if you can answer just one. These are questions that popped up whilst following an introductory...

Newton's law of universal gravitation states that every mass in the universe attracts every other mass with a force proportional to the product of their masses. See website for diagrams: http://hyperphysics.phy-astr.gsu.edu/hbase/forces/isq.html Inverse Square Law, Gravity As one of the...

why? i can see the link between spin value and the statistics in quantum mechanics

What is quantum foam, without using mathematics? Thanks

Hi, I have taken an introductory undergraduate QM course, solving for different boundary conditions like particle in a box, but the physical interpretations of some of the tenets was not well explained. I was surprised to find this paragraph on Wikipedia: "Published by Werner Heisenberg in...

I suppose I should post it here. It's not really a homework problem... And my question is: Is the validity of the vector approach in mechanics entirely based on its consistency with experimental results? Every time I do a question, I use the usual component resolution technique unique to...

hello everybody, I'm new here and new to the field of QM also. I have a few doubts regarding the double slit experiment. I know that there are other threads also here about the same thing, and you must be fed up seeing another one pop again, but I'm less brainy than those guys and have more than...

If Quantum mechanics theory is the most fundamental theory of nature that explain it at the smallest scale then it should explain Consciousness . I think that there may be deeper level of physics that can explain it . If consciousness is merely a quantum effect , it may be not only limited to...

what is inertial frame of reference. lets say motion is in 2d universe (x,t) consider three points f,a and b the distance of a and from f be x and y respectively. for what equation (s) of motion f would be inertial frame of reference for a ? what does it mean that Newton's law hold...

What does modern science particularly theoretical physics say about witchcraft ?

Imagine you have a high-speed camera with a capability to record almost near infinite frames per second. Would you be in principle able to record progression of light (I know that light itself is invisible so at least its reflected progression let's say off a room's walls after a light bulb has...

Homework Statement Here is an interesting reading to my question. http://coraifeartaigh.wordpress.com/2010/02/27/what-is-a-field/ The author wrote: The reason he said each charge will experience a different force is assuming different r (and not a constant r)? Another question is to...

My friend and I were debating if there really could be a perfect circle in nature outside the human brain? What do you think? If you think there is, please back it up with evidence.

Electromotive force is usually defined as the work done in transporting a unit positive charge in a round trip in the circuit. That is, EMF= loop integral of E.dL Now let us examine the above statements in the light of a constant source of emf driving a steady current in the circuit. If the...

About the wave nature theory ! In the case of Lunar Eclipse Hello all :) First I'm glad to be a new member of this forum .. Anyway .. as I noticed that if someone thought about a theory or a physics inquiry you share your thoughts and solve the problem .. So what came to my mind months ago...

I was wondering what the nature of a photon is, when I was thinking about different EM wavelengths.. If you compared the distance traveled by two photons of different energies, wouldn't the more energetic one travel a longer distance (assuming they have the same amplitude)? It seems like it...

A Gaussian function is often chosen as the amplitude function for the wave packet of a single particle. It is handy because the Fourier Transform of a Gaussian is also a Gaussian. So the position and momentum representations would both be Gaussians. But is there any empirical evidence that...

QED states that the magnetic field is a kind of "photon lattice" and the force we feel when a magnet pulls of something is the exchange of these virtual photons. But I become confused right about here, if the magnetic field is virtual photons, which are themselves wave packets of magnetic and...

Homework Statement This is a general concept question. The problem is, I don't seem to understand what the question is saying and why. Here's the question: A mechanical wave can propagate through a medium if a) there are attraction/ repulsion between...

While reading Lee Smolin's book "Three Roads to Quantum Gravity" in which he talks about the Bekenstein bound and a smallest fundamental unit of area, the following occurred to me: Suppose there does exist such a smallest unit, call it A. Then there exists a smallest volume, V(a). A...

Learning about the nature of current, the Ampere and its role in Epsilon0. I'm assuming that the fact that the Ampere is defined in terms of electrons per second is arbitrary and that it could just as well have been protons per second? And if it had been protons per second, then Epsilon0 would...

Hello, this is a first year undergraduate student speaking, thanks for taking the time: 1) Is it unphysical (in a perfect realm, etc) to say "one EM wave"? With which I mean: an infinite mathematical line with for each point an E and B-vector defined varying sinusoidally. In other words...