03/03/11 12:59 PM
Does any one know why masses attract each other or why a positive charge attracts a negative charge………,??
03/03/11 2:33 PM
SO, why +ve charge attracts negative charge….
-I am an Underdog in Science
03/03/11 3:14 PM
Gravitational attraction of masses result because masses introduce curvature to space-time. You can start reading about it, e.g., here: http://en.wikipedia.org/wiki/General_relativity
Coulmb attraction or repulsion is due to the exchange of photons. You can start reading about it here: http://en.wikipedia.org/wiki/Quantum_electrodynamics
03/04/11 2:07 AM
Josef is spot on in his answer…Although some people would immediately start talking about Higgs bosons and Gravitons, in my opinion not necessary (in general)… But, it can be good to know that the hypothetical Higgs boson is the field that interacts with particles to give them mass, and that the graviton is the theoretically predicted quanta of the gravitational field. So suppose we would have a quantum field theory of gravity as we do for electromagnetism, then the graviton would be the particle which mediates the gravitational force much like the photon for QED (Quantum electrodynamics).
An interesting side-note:
The electrical potential (the columb-barrier) is the reason why we bump off and not through each other :)
03/04/11 2:05 PM
Good answer Mikael and I didn’t check the pointers Josef (but wikipedia is usually useful)
The masses attract each other because as noted by Mikael masses have the ability to warp or curve the space time fabric of the Universe. In other words if space and time together can be imagined like a sheet of cloth which is flattened then by allowing a heavier object on this sheet what happens is the sheet that our Universe is, becomes curved much in the same way a regular sheet of cloth would be.
So other lighter masses in the vicinity of the heavier masses have a way to fall towards the heavier mass, so this is a very apt analogy how in Real Universe all masses are causing every other mass to move nearer.
As far as charges are concerned since there are two kinds (and then the neutral kinds) the opposite charges create opposite kind of lines of forces in their surrounding which in it’s magnitude goes in the same way the masses create, that is an inverse square of the distance, but in case of charges, charges can either move towards each other or away from each other.
The other details are our advancement in understanding such as the Higgs boson which is as of now undiscovered but possibly going to be discovered by the Large Hadron Collider machine in the near future, this Higgs gives the ability to every other particle known, to acquire such ability to curve the space time around them, that is, have the property called mass.
Apart from the Higgs boson the LHC or the proton smasher will have the ability to discover many new hitherto known but undiscovered phenomena such as a super partner to every known particle. So an electron like it has a partner called anti electron or positron will have another called a Selectron or a super-electron, a proton will have a partner called sproton and so on.
03/04/11 2:20 PM
The space time fabric theory as you said is cool but how does it account for the fact that gravitational force is superbly weak before the other forces electromagnetic strong weak . And the real question was how DO the opposite charges attract each other and same repel……
03/04/11 2:42 PM
The space time fabric is an analogy so that those who want to understand the implications of general theory of Relativity in simpler terms can do so. Its not absolutely necessary for my understanding. For my understanding its enough that Space time is warped in presence of mass and this is a brilliant progress in understanding by Einstein.
I can ask someone why human beings are here after all and why we behave and respond the way we do, NOBODY has an answer to that. Why our planet which is the only one known so far to sustain life exists on one spiral arm of the Galaxy and not in the center, NOBODY knows that answer.
Why there is a black-hole at the center of every galaxy and possibly more than one, NOBODY knows, they are just there. Why masses warp space time, it just does. Why gravity is weaker than other forces and yet cosmological in its scale NOBODY knows, we don’t even know if there could be another or many more fundamental forces, let us wait for LHC results from next 10 years, We don’t know what we will come across.
There are 100s of open ended questions and the fact that Gravity is a weaker yet cosmological force is one of them.
03/04/11 2:47 PM
The answer to your other question I just gave, opposite charges create opposite kind of lines of forces, one is converging and the other is diverging. The whole idea is, that is why we know that there are 2 kinds of charge because they create 2 kinds of lines of forces, the fact that we discovered two kinds of charges is it’s empirical in nature.
Most discoveries are empirical in nature so its a little twisted the way you posed the above two questions. Why Gravity is weaker, its weaker by nature, as we know. Why there are two kinds of charges, there are two kinds as we have found experimentally. Why there are 4 fundamental forces, because we have discovered only 4 of them so far.
Why the ordinary matter is only 7 or 8 % of the total matter present in nature, may be because we have to call it ordinary matter. When we will discover dark matter and dark energy we will know more about our Universe and we will have thousand more whys… That will be exciting time for human community as a whole
03/04/11 8:49 PM
Thanks Manmohan….consider for a moment the discrete nature of spacetime as indicated by many theories… then perhaps the analogy of the fabric of space is more than just vizualizing a concept…don’t you th…ink?
03/04/11 9:09 PM
Mr manmohan you may have heard of various theories such as the strings multiverse supergravity… the m theory……. etc which say that the gravitons are actually vibrating super strings (type of super string structurally different) which are responsible for gravitation . Mixing this concept with multiverse which makes that these gravitons are able to pass through the parallel universe as they do not mingle with the membrane (m theory) so they easily pass through . Due to passing to some other parallel universe the strength of gravity reduces in our universe . ( mathematically gravitons are coming from some other parallel universe to ours ) please put some more light on the topic…….. Thanks……..:-):-):-)..
03/04/11 9:11 PM
Hi Mikael, true, we have made some progress in unifying quantum mechanics with gravity, but not there quite yet, that we can substantiate as a profound evidence or a new discovery. Neither theoretically nor experimentally have we discovered such a unification as of yet.
Going by the way science is established, going by how quantum mechanics itself took 3 decades for its ideas to be even appreciated and evidenced and accepted and going by how the loop holes of unification aren’t yet solved after mind-blowing success in 60s and 70s of last century we are still ahead in speculation than in establishment of foundation of a new theory or discovery.
I wouldn’t call it speculation or visualization if another person wouldn’t. I have my inclinations to keep quiet at an intuition of mine if another person isn’t quite comfortable with it, or else I would be called a Wuss or wart rather than a scientist.
Bohr’s model is similar to the space time curvature model. Now Bohrs model is equally an astounding visualization but everyone knows it’s the work of a genius, that is, from a stage of no idea to an idea which gives us tremendous power to imagine and intuit about something that no one sees.
About Graviton, the LIGO observatory through an interferometer is capable of measuring a 10 to the negative 18 distance scale. Thats their recent claim. They are capable of measuring such a fluctuation in the deflection of a 1 KG mirror induced by a graviton. They haven’t yet measured the graviton with such sensitivity.
SO the scientific community has to wait till other independent experiments and theorization gives a solid proof. Vinamra you are absolutely right, its still a proof that its just more than visualization, but visualization of something as subtle as the geodesic of our Universe at any scale isn’t after-all low grade Physics. It is still the highest quality Physics we have, so I am going for such an analogy.
Fco. Javier Mateos
03/04/11 9:31 PM
Thank you, Mr. Manmohan.
On the subject of analogies and science.
For my work (creativity and engineering knowledge)
See particularly well suited (and fruitful) to work with analogies.
Whenever you never forget that these are only analogies and never would give the result more value than a “good approximation”.
Another advantage is that being an analogy maintain a healthy skepticism about the model chosen by our imagination to picture the phenomenon.
The history of science is full of these examples, Maxwell, Zeldovich, Vant ‘Hoof, etc.
One answer brings me to old personal questions (perhaps the result of my ignorance but I assure you the result of common sense … :)
How can distort the space time matter?
Allow me, please use an analogy (not forgetting that it is only an analogy!)
If the matter (or energy) may wrinkle the spacetime.
Particles are a form of wrinkle or deformation constant and characteristic?
Answer or his description seems somehow to solitons?
We could achieve a “wrinkle” space-time?
If you point out what they have in common two things I do not mean they are the same thing, but what they have in common can be used for something!
03/04/11 10:09 PM
OK !! Vinamra !! this is what I would think a priori without more knowledge than the people who are actually working on this which I am in no way a participant of except through my own understanding. Also I wo…uld like to say this. Physics or any science is an involvement of the most learned and everyone who interacts with this ideal is learned so this basis of science gives me some confidence to apply very basic knowledge of quantum mechanics to everything that you have mentioned here gravity, super-gravity and multiverse. I have often said the following, especially very recently that anything is true in our world as long as its inconsistency isn’t glaringly visible. This is a fundamental tenet of quantum Mechanics very easily forgotten by most, where as we know that it’s not any other theory such as string theory or M theory but Quantum Mechanics that is the sole guide when it comes to explain anything we have known in our world.
(Mostly this is known as Standard Model since standard model has in it everything that is valid as of 2011, most people do not understand the meaning of standard model, standard model is Mr quantum mechanics)
It’s further expansion leads us into M theory or the likes. So as long as anything said by String theory or M theory does not invalidate our notions of standard model or even quantum mechanics basics its going to be held as something that draws attention of serious scientists.
SO this is like what Niels Bohr says, anything that is not crazy isn’t going to be much of an idea either, now by crazy I mean something which is acceptable in the discourse of learned scholars rather than popular misconception, some ideas can still be more crazy than popularly held by most learned scholars, still let’s give them a shot.
SO with such intuitive approach in my mind I am thinking about the ideas put forth by you. Multi Verse as such isn’t excluded by quantum mechanics. A very basic effect you might have noticed is fuzziness, if you swiftly move an object in a matter of a short time and take its picture you will see that its smeared across multiple spaces even if the object in classical reality is not as extended.
That is telling us a lot about the actual reality of our world. The way objects of reality exist they exist as waves, that is extended phenomena, not necessarily localized mass objects called particles. We only need to have enough facilities to observe such. When the camera shutter closes, it gives a very small time period during which the wave nature of a particle object is visible.
Similar things can be said about our Universe as a whole. We observe it to be a 3 Dimensional space and one dimensional time object. That means our Universe can actually be observed through a very small time period during which its various other extensions smeared out into multiple existence will be visible. What we observe is a classical Universe.
But what actually exists is a superposition of many Universes with various likelihoods, just like the fuzzy smearing of the object in motion. You can produce a fuzzy picture of your hand or the rim of a bicycle wheel or a fan that’s moving slowly so even with naked eye you see more than 3 blades when in classical reality there are actually 3, when the fan stops.
SO our Universe is a superposition of many Universes and what possibly these string theorist are saying is, a graviton as we would measure in our part of the Universe is much weaker in its mass, that is, energy, than the other components of this graviton present in other superposition modes of the Universe.
03/04/11 10:34 PM
Javier, it was a little difficult to understand in exactitude your concerns, seems you are using some forms of internet translation of which I have become victim recently. But the statement you made about analogy is so apt that I find it brilliant. About your other points, YES matter and therefore energy wrinkles space time, by doing so they attract each other as we have discussed above.
About Particles being forms of wrinkles in space time, I do not know perfectly. Consider it imperfect ignorance. But certain particles exist for eternity, such as a proton, so I do not think they are actual wrinkles of space time, rather they just move by warping the space time and that’s how their interaction is effected. The particles that exist for only but a small time, such as electron or mesons which I have studied in some or other way, are created from other particles so the parent particles have no reason to produce them from wrinkling the space time although such wrinkles exist by their own nature and affect the way these particles would interact. Take the example of small balls and balloids and sand cakes, they may contain water but they are made up of silicon and other such matter, merely floating in water does not make them water like.
Who said this (??), need better book keeping
Well I don’t know if i should post here or on epernicus. Seems it will prove same ….. Now coming to point . The FIELD you told me about responsible for charge attraction and repulsion . To my maybe wrong intutions it doesn’t seem to be an apt answer the distance between attraction and repulsion for which the Coulombic forces hold good for several thousand kilometers and even more .
If it is caused by (what you mentioned before) the distance till which these forces remain functional should be a hundred meters or so ….. And to my knowledge according to QED the electrostatic force between electron and proton causes attraction between the two but photons are emitted from the nucleus which repel the electron these forces maintain the balance in the atom. I may be wrong about above… Please clarify ..:)
03/05/11 9:51 AM
The answer to your first part is really simple…You find the form of the force from observation and experiment to be a force which varies as an inverse square in distance, SO if you draw such a mathematical function it goes to zero at an ever increasing distance, that is infinity. SO electromagnetic force extends to infinity not just 100 mets or kms, but in effect practically zero after a very short distance, but in QED which also makes these quantum predictions a field created in another galaxy will influence a charge here in our world, but this is only required to make a good theoretical calculation so we could avoid any infinity from our theories.That’s the beauty of Physics, infinities must be avoided if possible to get insight into how things really work in nature. The whole broadcast system is based upon such an approach, so we know how to get electromagnetic relays even from across Mars where we have put our satellites. For the second part, I don’t know why the photons will be emitted from the nucleus and why it will repel the electron, but to keep the balance between the various constituents in the atom we have another force called strong force which acts in a very short range (inside the nucleus) it holds protons and protons and neutrons and neutrons, everything together, as positive protons will repel each other from electrostatic repulsion.
03/05/11 12:37 PM
The range of strong force is very less upto some distance it acts like an attractive force but after that it turns repulsive . If the charge attraction is balanced by the strong force. Then all the electrons will be seen to move towards the nuclei and when they reach utterly close to the nuclei strong force will repel them so electrons will be moving like from 1st 2nd 3rd …nth shell going towards the nuclei till they are very close then repeling and after going a distance again marching towards the nuclei :).:)…..:) ….does this happen..:….:
03/05/11 12:41 PM
The lines of force you told about before aren’t they imaginary. How do these lines of force do the trick . You can’t say some imaginary lines are the answer of this phenomenon.
03/05/11 1:24 PM
The lines of force aren’t imaginary at all, they are as real as the lines drawn on your shirt, a few years ago I gave demonstrations to undergrads at Virginia Tech about such lines of force emanating from a magnet. So a set up was created where the students drew the actual lines of force on a board by placing a magnet and a magnetic needle. SO the direction of the magnetic needle gives the lines of force and as you put the needle at different places the lines of forces are viable. This was drawn for a dipole magnet.
03/05/11 1:25 PM
The other part of the question about strong force I will answer later…
03/05/11 2:06 PM
Strong force is between protons and neutrons only, since they have quarks inside them. In general it works only on quarks, mediated by the force carrier gluon. It neither acts on electrons, electron is a lepton as opposed to a quark, nor it acts on any other charges as such. Also it’s (available in a) short range and does not act outside of nucleus.
03/05/11 2:15 PM
First, back to the nature of space: Manmohan you are absolutely right in that we have no evidence of the discreteness of space-time… but the fact that space has a structure (discrete or not) does not need more evidence than the proofs of relativity itself… Also Zero-point energy can be viewed as an indication of the aforementioned. So…the likelihood that the structure of space is discrete is in my opinion high, regardless of the progress towards unification by various theories.
Theories, such as string theory and others all have some very interesting and seemingly logical parts…but to me it seems like there is something that is being overlooked; kind of like missing the forest for all the trees. Ultimately it comes down to what appeals you; people work on what they find interesting and most are aware that it can turn out to be in the wrong direction.
So the standard model is solid, but it does feel..how should I put it…limited maybe… like an enclosed capsule… So anyway…CP violation is very interesting and it’s implications can guide us towards new directions…
Vinmara: “….photons are emitted from the nucleus which repel the electron…” – What you are talking about here is an atom being excited and hence it emits the extra energy as photons (at a certain threshold). Electrons are never repelled by the nucleus, rather, they escape from it. When an electron is sufficiently excited by electromagnetic radiation, for example, it goes into an higher energy state at a certain point it can escape despite it’s bonds, hence creating an ion…
Manmohan: I read you research description on your profile: could you tell me, is Cabibbo favored and suppressed channels of the equivalent to the probability of Cabibbio angles of decay?
03/05/11 2:20 PM
YOU can now see our discussion on my wordpress site
03/05/11 2:36 PM
Photons are the Bosons of electro magnetic force that is particle responsible for the electro magnetic force or we can say Coulombic forces . It is believed that interaction of photons are responsible for the electromagnetic force and about the nucleus emitting photon … I read an article describing why the electron does not fall in the nucleus due to the inward force of nucleus and repulsion from electrons in the outer shell
03/05/11 2:38 PM
Then What are these force lines actually made up of and how do they interact (bring up changes)
03/05/11 2:42 PM
You can view the discussion here webmohan.wordpress.com/2011/03/04/interesting-questions-about-space-time-particles-multi-verse-and-string-theory/
03/05/11 3:16 PM
Ok. I see what you mean, Vinamra. I would say, though, that electrons do not crash due to the energy state/level. If we solve the Schrodinger equation we get a mathematical description of every allowed energy level of the electron. From that we can read that the lowest possible energy state, consistent with quantum mechanics, is still a positive energy state, keeping it away from the nucleus.
03/05/11 8:12 PM
Mikael, YES. The branching rates (the rate at which these channels occur in nature but given as a rate-fraction of their parent modes) of these CF and DCS decays, are given by probabilities that depend on the angle called Cabibbo angle that is why the name Cabibbo Favored for the decay channel that is favoured or occur at high rate and the doubly suppressed is the channel which is a lower rate, by two factors, as a function of the Cabibbo angle (so not arbitrary) Vinamra, you are absolutely right, that Photons are the quantum of electromagnetic field
(so there are no lines of force in such a scheme and YES this is called a Boson because it has integer spin,1)
and every charge interacts with every other by exchanging a photon (Feynman diagrams). SO nucleus can emit photons that are absorbed by electrons in any shell and these electrons get more excited or energetic, they can also lose some energy in forms of these photons
In my CF and DCS studies, I studied all sorts of particles, electrons, photons, mesons etc so they all make sense how the electromagnetic quantum theory is valid, its called QED and its integrated into Standard Model.
Mikael, it is limited but its also the latest comprehensive valid understanding or in other words Standard Model is Mr Physics when the standard model of Particle Physics and Astrophysics, Cosmology are combined, the limits (edited: and limitations) are to be there, like what we are discussing here about lack of certain unification.
Of-course when I say Mr Physics one has to realize that that’s in the sense of all techniques, methods, concepts etc so one doesn’t have to bother about where other branches of Physics are, well its not a matter of pride.
SO why the electron does not fall into the nucleus because it never loses enough of energy to do SO. It’s energy credit line and over draft are quite well defined because of presence of nucleus, as Mikael says through Schrodinger’s equation.
The quantization and unification are about upholding earlier valid understanding of everything, Maxwells equation, Special Relativity, even the classical observations such as stability of atom.
SO the latest standard model (it gets updated, in Particle Physics it gets updated every two years ) takes care of everything, it has in it the methods and techniques of all the theory and experiment known to scientists. (of the corresponding fields of studies)
About lines of force they are not real in the sense of actual lines existing in nature like strings or ropes but lines or direction of force. Now would you say the direction in which you are moving is unreal?