Can someone explain quantum physics?

[Phanerothyme]

Phan - How did you reach the conclusion about not having computers, tv's or radios without consciousness affecting quantum states?

 

The issue of consciousness, or perception 'collapsing the waveform' wasn't related. I just pointed to that as one of the interesting ramifications of the interpretation of quantum theory.

 

But an understanding of quantum theory, and how it affects the real world, is intrinsic to the radio and data age.

[rip_dime]

The term quantum (Latin, "how much") refers to discrete units that the theory assigns to certain physical quantities, such as the energy of an atom at rest (see Figure 1, at right). The discovery that waves could be measured in particle-like small packets of energy called quanta led to the branch of physics that deals with atomic and subatomic systems which we today call Quantum Mechanics. The foundations of quantum mechanics were established during the first half of the twentieth century by Werner Heisenberg, Max Planck, Louis de Broglie, Niels Bohr, Erwin Schrödinger, Max Born, John von Neumann, Paul Dirac, Albert Einstein, Wolfgang Pauli and others. Some fundamental aspects of the theory are still actively studied.

 

Quantum mechanics is a more fundamental theory than Newtonian mechanics and classical electromagnetism, in the sense that it provides accurate and precise descriptions for many phenomena that these "classical" theories simply cannot explain on the atomic and subatomic level. It is necessary to use quantum mechanics to understand the behavior of systems at atomic length scales and smaller. For example, if Newtonian mechanics governed the workings of an atom, electrons would rapidly travel towards and collide with the nucleus. However, in the natural world the electron normally remains in a stable orbit around a nucleus — seemingly defying classical electromagnetism.

 

Basically its physics in real detail

[defstef]

If you cut any object and split it again and again, until you have the smallest particle, you get an atom. You can view an atom by strong microscopes.

Depends what you mean by 'view'. It's impossible to resolve features less than half the wavelength of the 'light' (or any other electromagnetic radiation) that you are using - the so-called diffraction limit. Electron microscopes, scanning tunneling microscopes (which themselves makes use of the classically forbidden, QM-allowed phenomenon of electron tunneling) and atomic force microscopes all allow atomic resolution of features. X-Ray diffraction and neutron scattering in crystalline materials allow structures to be determined at an even greater resolution. 'Determined' is the key. It's worth remembering that, whether you 'view' a molecular-scale object as a computer-generated image based on electrical signals from a probe scanning over a surface, or you look at a tree with your naked eye, what you are 'viewing' is a virtual representation of a real object (either electron clouds on atomic surface interacting with a probe which causes an electrical signal which is amplified and interpreted by a computer, or electromagnetic photons bouncing off a tree, into the eye where it causes a molecule to change conformation which causes an electrical signal to be propagated along a nerve fibre into the visual cortex where an image is reconstructed).

 

However, if you split an atom and want to look inside it, I don't think you can see it. Smallest particle inside an atom are (by guess work), electrons, protons, and neutrons. With negative electrical charges, positive electrical charges, and no charges respectively. These particles are the smallest particles known to man, and it is widely accepted as scientifically true. Its existence are proven by experiments. However, I don't think you can see the electron, proton, or neutron by the most powerful microscope.

See above...

 

Now, Quantum Physics is about the interactions of these sub-particles, (if they are indeed particles), inside the proton and neutron. (I think this is right, cos both of these have a mass, whereas an electron has no mass, but just a charge.)

 

Quantum physics is about how these particles (known as 'quarks' ?) bump into each other, and how they interact to produces the effect that is seen inside an atom. I think theories in this area is still being debated, and scientifically proven. i.e. how fast they are, how they move, when do they move, which direction do they move etc etc etc

 

I think nightrider summarised QCD quite well. Quarks (3 of them in each) constitute each hadron (protons and neutrons). Electrons certainly do have mass! I think you're doing a disservice to chemistry by calling yourself a chemist.

 

All of the above is a digression, anyway. I think it is possible to have *some* understanding of quantum physics, in layperson's terms. Feynman's statement was typically flippant, and he was as much expressing awe at nature as he was stirring and provoking his contempories (he famously hated the concepts of eminence and authority in scientific endeavour).

 

Certainly the historical derivation of Planck's law for blackbody radiation is central to any real understanding (quantum superposition and entanglement are all very exotic and exciting, but they don't really lend any understanding to the more fundamental concepts, which is what I think the OP was getting at). In this, Planck overcomes the failure of Josef Stefan's and Wien's earlier efforts to relate the energy given off at all wavelengths from a black body at a given temperature, which, if extrapolated from these simple laws, predicts that the universe should be awash with massive amounts of ultraviolet radiation. It isn't. Planck's work draws on the statistical mechanics of Ludwig Boltzmann, and also features a 'fiddle', Planck's constant. Basically, this fiddle means that you can only add or take away energy from a system in discrete amounts, or quanta, due to the electron energy shells in the atoms that make up the systems. A simple analogy is digitization of an analogue signal (which, as we now know, must be product of a 'digitized' quantum system anyhow).

Planck's constant appears in many physical laws, whenever electromagnetic radiation interacts with matter. A famous example is the photoelectric effect, whereupon a photon incident on a metallic conductor causes movement of electrons (a similar phenomenon powers conventional photovoltaic solar cells, albeit with semiconductors). Common sense, and classical physics, would lead us to believe that the rate of flow of electrons would depend on the intensity of the radiation (the number of photons) hitting the surface, but it does not. Only the frequency of the photons (rate of oscillations per second) matters, along with an intrinsic property called the work function. Determination of the true nature of the photoelectric effect earned Albert Einstein his Nobel Prize in 1921.

 

While it's worth highlighting the more exotic consequences of quantum physics, I think a layperson's explanation should be grounded as much as possible in the fundamentals.

[Merry_Legs]

I kind of associate it with black holes, anti matter, dark matter, what's the matter, neutrinos, quarks and string theory. I get it all a bit mixed up really.

[Cyclone]

The issue of consciousness, or perception 'collapsing the waveform' wasn't related. I just pointed to that as one of the interesting ramifications of the interpretation of quantum theory.

 

But an understanding of quantum theory, and how it affects the real world, is intrinsic to the radio and data age.

 

Radio and computing devices were invented well before quantum theory was established though. Quantum level effects are only just becoming relevant to computing now, and actual quantum computing is still in the mostly theoretical stages.

[Cyclone]

what's the matter is one of the hardest quantum effects to understand, or so I find when talking to women.

[defstef]

Radio and computing devices were invented well before quantum theory was established though. Quantum level effects are only just becoming relevant to computing now, and actual quantum computing is still in the mostly theoretical stages.

You could actually argue that the development of radio (which was helped along greatly by Maxwell's work) led to increased interest in the manner in which electromagnetic radiation and matter interact, furthering study into the photoelectric effect and the nature of black body emitters (see my above post), and therefore quantum mechanics. Effectively, radio prompted the concept of quantum mechanics!

[defstef]

what's the matter is one of the hardest quantum effects to understand, or so I find when talking to women.

Especially when nothing's the matter. Maybe zero point energy empowers a woman scorned?

[Cyclone]

Wrath powered by quantum foam, I can see the headlines now.

[Bago]

Oh Gawd, this seems to be the thread of pedanticism.

 

I've skipped the last 8 or so posts, but to summarise, bago you description was basically nonesense. If your A-level physics teacher heard you he'd have a fit.

Why would he have a fit ? I have merely laid down the ground for the basics. I haven't even mentioned the wave-particle theory yet ! Whereas a lot of people have already given names of Physicists, and Principles. Yet, exactly what are they about ? Huh ? Since no-one really deconstructed it, how can a non-scientist understand what is one theory over another ? How about decoding the basics by going into analogies and layman terms ? I presume if one understands the concepts, then you an use other analogies to explain what you are seeing, rather than quoting directly what can be found everywhere on the Net ! I still think that merits should be given on what I have posted. ! I distinctively stayed away from terminologies which are not easily understood without going into details of theories and principles.

 

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Electrons do have mass as do protons and neutrons.

 

Electrons have no mass. This is true relatively, and on a very basic level of understanding, because Electrons' mass are negligible compared to a proton ! If we're not going to go into an equation definition mode, then does this really matter ? It's what's known at a basic level. From wikipedia:

 

Electrons have a negative electric charge of −1.6022 × 10−19 coulomb, a mass of 9.11 × 10−31 kg based on charge/mass measurements and a relativistic rest mass of about 0.511 MeV/c2. The mass of the electron is approximately 1/1836 of the mass of the proton. The common electron symbol is e−. [1]

 

In physics, the neutron is a subatomic particle with no net electric charge and a mass of 939.573 MeV/c² (1.6749 × 10-27 kg, slightly more than a proton). Its spin is ½. Its antiparticle is called the antineutron. The neutron, along with the proton, is a nucleon.

 

In physics, the proton (Greek πρῶτον proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1.602 × 10−19 coulomb), a diameter of about 1.5×10−15 m, and a mass of 938.3 MeV/c2 (1.6726 × 10−27 kg), or about 1836 times the mass of an electron. The proton has a density of about 2.31 × 1017 kg m−3.

 

Electron = 9.11 × 10−31 kg

Neutron = 1.6749 × 10-27 kg

Proton = 1.6726 × 10−27 kg

 

The proton and neutron, which are similar in mass, each weighs approximately 1,836 times greater than a single electron, thus the mass contributed by electrons is insignificant when determining atomic weight or atomic mass. The atomic mass is the sum of the protons and neutrons in the nucleus.

Source = http://environmentalchemistry.com/yogi/periodic/atom_anatomy.html

 

GCSE/A level = http://www.chemguide.co.uk/atoms/properties/gcse.html#top

 

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If you cut any object and split it again and again, until you have the smallest particle, you get an atom. You can view an atom by strong microscopes.

Depends what you mean by 'view'.

When I wrote this, I just knew someone will pick at it. Shall we say, an ELECTROMAGNETIC microscope. So therefore we can 'view' this. Apart from the ability to view it electromagnetically, I don't think (yes, my opinion here) anyone else can view the sub-level below the atomic level ! (Enlighten me if it does exist.) We are only using theories to predict what we see. Do electrons, neutrons, and protons really exist ? Yes, you can prove by experiments that they exist. However, can you prove that the 'matters' (hadron) which makes the neutrons, protons really exist ? If we go beyond this level of particles, then it goes into theory mode, which is, as I understand it, what Quatumn physics were about !

 

I think nightrider summarised QCD quite well. Quarks (3 of them in each) constitute each hadron (protons and neutrons). Electrons certainly do have mass! I think you're doing a disservice to chemistry by calling yourself a chemist.

LOL. Bloody cheek !

 

Yes, I can call myself a chemist. Yes, I think that as a relative mass, it is insignificant to know the mass of an electron within chemistry ! We like to know where it moves, and not how much it weighs. Chemistry don't really bother much with it ! What I am not is anal with the definitions in science. Yes, I understand that you think I am being of a dissservice to my degree, or even to my physics teacher cos I am not going by the true (classical) definitions of it. However, this thread is about a person wanting to understand something, so, I am doing my best to deconstruct that. He does not need to know the tiny details, and confuse himself over it. That is for sure. Why throw the idea of Newtonian theories, when this is not known from one to another ? Also, when were the ideas of quark introduced, and particles taken place ? A lot of theories are thrown around, which is not solely exclusive to Quantum Physics anyway but a more general understanding of physics overall. This distinction has not been made. So the Joe Blogg may walk off thinking, "Oh, so Quantum Physics means this, and this, and this". Not entirely true.

 

As demonstrated by the amount of anality of this thread, I think it's safe to say that, many people just throws ideas here and there, and cannot bind it together and write in a true layman term which can be understood by all.

 

 

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I think this sums it up well:

 

http://en.wikipedia.org/wiki/Introduction_to_quantum_mechanics

 

It binds ALL the theories as suggested in this whole thread.

 

I think this also sums it up well.

http://en.wikipedia.org/wiki/Standard_Model

It takes it beyond GCSE/A level, and even degree level, and into research areas.