Newton's Second Law - Not Complete?

I was at Borders the other day, waiting for the wife to buy her 67th pair of black heels :roll: , when I came across this month's issue of Discover Magazine.  

In it, there is a article on what is called MOND -MOdified Newtonian Dynamics.  It claims that F=ma is a high acceleration appoximation of a grander law that describes all accelerations.  The guy who came up with it was working on the rotation rates of galaxies.  He noticed that F=ma works for most things, but at very small accelerations, it does not hold.

Under MOND, the new equation would be F=m((mu)(a/a0))a.  Where a0 is a new constant of acceleration and (mu(x)) gives 1 if x>1 or x if x<1.  

This seems to be a trade off between dark matter and inventing new math.  On one hand, we have this matter that can't be detected, but seems plausable to be in existance and on the other we have math formulas that are rewritten to fit the data.  However, the new formula has been shown to accurately describe the lensing effect and 'fix' the mass discrepency of the universe.  

I'm big on theorectical physics and this was new to me.  Anyone else heard of this?  

Here are some links:
http://en.wikipedia.org/wiki/MOND
http://www.astro.umd.edu/~ssm/mond/faq.html

I was at Borders the other day, waiting for the wife to buy her 67th pair of black heels :roll: , when I came across this month's issue of Discover Magazine.  

In it, there is a article on what is called MOND -MOdified Newtonian Dynamics.  It claims that F=ma is a high acceleration appoximation of a grander law that describes all accelerations.  The guy who came up with it was working on the rotation rates of galaxies.  He noticed that F=ma works for most things, but at very small accelerations, it does not hold.

Under MOND, the new equation would be F=m((mu)(a/a0))a.  Where a0 is a new constant of acceleration and (mu(x)) gives 1 if x>1 or x if x<1.  

This seems to be a trade off between dark matter and inventing new math.  On one hand, we have this matter that can't be detected, but seems plausable to be in existance and on the other we have math formulas that are rewritten to fit the data.  However, the new formula has been shown to accurately describe the lensing effect and 'fix' the mass discrepency of the universe.  

I'm big on theorectical physics and this was new to me.  Anyone else heard of this?  

Here are some links:
http://en.wikipedia.org/wiki/MOND
http://www.astro.umd.edu/~ssm/mond/faq.html

Newtonian Physics work great with everyday objects and speeds. But extreame enviroments require General Relativity or Quantum Physics. (maybe m-theory if it works)

Newtonian Physics work great with everyday objects and speeds. But extreame enviroments require General Relativity or Quantum Physics.

...which would be the point of MOND.

Having heard of MOND (an article in SciAm whose contents I've forgotten) but not read much about it, does MOND add predictive power over what we get from General Relativity?  Or does it merely make Newtonian mechanics agree more closely with GR?

From the article, they made it sound like GR was wrong.  However, after more indepth searching, it appears to either 'correct' GR or at least makes Newtonian mechanics work better within the framework.

Trying to make Newtonian Dynamics fit into Quantum mechanics is like trying to make sparrow swim and a Salmon Fly, whatever happens it won't be pretty and you will most likely be dissapointed.


Newtonian Dynamics rely on Certainties, and Quantum Mechanics on Probabilities.

General Relativity is, generally, just an evolution of Newtonian Dynamics.

So the difrenece between MOND and Relativity just sounds like the difference between Netwonian Calculus and Liebniz Calculus

Trying to make Newtonian Dynamics fit into Quantum mechanics is like trying to make sparrow swim and a Salmon Fly, whatever happens it won't be pretty and you will most likely be dissapointed.

I don't believe MOND was intended to be a TOE.  I think it was intended to replace dark matter.

sorry TOE??? i hate trying to figure out what acronyms mean i would search on google for what it stands for, but i imagine i would get quite a few strange fettish sites ;-)

sorry TOE???

Sorry, TOE stands for a Theory Of Everything.   String theory is trying to unite QM and GR, so it is a TOE.

Einstein tried to make a theory of everything, and by trying to do so he violated his own postulates, and before he died he stated that his toe was total bollocks and a waste of time.

Does the development of MoND negate the problem of entropy? (I know that is a result of Newtonian physics coming to their ultimate conclusion).

Trying to make Newtonian Dynamics fit into Quantum mechanics is like trying to make sparrow swim and a Salmon Fly, whatever happens it won't be pretty and you will most likely be dissapointed.


Newtonian Dynamics rely on Certainties, and Quantum Mechanics on Probabilities.

General Relativity is, generally, just an evolution of Newtonian Dynamics.

So the difrenece between MOND and Relativity just sounds like the difference between Netwonian Calculus and Liebniz Calculus

errm, you do realize that we are getting pretty close to combining GR and QM. And no, GR is a completely different way of looking at the universe, space, and time from newtonian physics. It is a classical theory though as it doesn't incorporate the uncertainty principle.

Does the development of MoND negate the problem of entropy? (I know that is a result of Newtonian physics coming to their ultimate conclusion).

what problem?

Einstein tried to make a theory of everything, and by trying to do so he violated his own postulates, and before he died he stated that his toe was total bollocks and a waste of time.

Because he refused to accept Quantum Theory. If he had acceptted it and worked with it and not to tryed to disprove it, perhaps he could of had a shot at a ToE.

People forget that when Einstien said "God does not play dice.", referring to the uncertainty principle of quantum physics, he was proved wrong. Very wrong.

thats true he was developing his ToE to try and refute an off shoot of his own theory, but einstein before he died restated the "God does not play dice" with "God does play dice, but the dice are loaded"

Quote from: "Dogplatter"

Does the development of MoND negate the problem of entropy? (I know that is a result of Newtonian physics coming to their ultimate conclusion).

what problem?

The problem that under heliocentric, Newtonian physics, the energy in the universe is projected to eventually run out, causing the heat-death of the universe and preventing anything from happening.

well the universe will probably suffer a heat death



but we ain't gonna be around to see it.... hell earth ain't even gonna be round to see it

thats true he was developing his ToE to try and refute an off shoot of his own theory, but einstein before he died restated the "God does not play dice" with "God does play dice, but the dice are loaded"

actually no, wrong again. His famous EPR paper that attacked quantum entanglement and non-locality has actually been used time and time again to prove him wrong. Einstien, Poldolsky, and Rosen claimed that entanglement was actually just the result of hidden variables in the particles and quantum theory was incomplete because otherwise it would violate locality. Locality meaning that only particles in proximity of each other can effect each other. Turns out the EPR paper was wrong on both points. There are no hidden variables in entanglement, the particles have the same quantum state and are linked together. Whatever happens to one will happen to the other. This also violates EPR's notion of locality, which is also untrue. Particles do not have to be in proximity of each other, to affect each other.

The dice are NOT loaded. There are no hidden variables.

on another note, why are we arguing about newtonian physics(1700s), GR(1915), and quantum physics(1930), all of them are old news in the science world.

on another note, why are we arguing about newtonian physics(1700s), GR(1915), and quantum physics(1930), all of them are old news in the science world.

This thread was originally about MoND, which is relatively new.  Yes, we all know about your love for inflationary cosmology and string theory, we get it.

Quote from: "troubadour"

on another note, why are we arguing about newtonian physics(1700s), GR(1915), and quantum physics(1930), all of them are old news in the science world.

This thread was originally about MoND, which is relatively new.  Yes, we all know about your love for inflationary cosmology and string theory, we get it.

then talk about it if you get it. it's what's NOW.

Quote from: "TheEngineer"

Quote from: "troubadour"

on another note, why are we arguing about newtonian physics(1700s), GR(1915), and quantum physics(1930), all of them are old news in the science world.

This thread was originally about MoND, which is relatively new.  Yes, we all know about your love for inflationary cosmology and string theory, we get it.

then talk about it if you get it. it's what's NOW.

This thread is about MoND which is NOW.  If you want to have a discussion about string theory, start a thread about it.

hell earth ain't even gonna be round to see it

The Earth was never round to see it  :lol:

hehe that was a great responce dogplatter =)

Quote from: "DrQuak"

hell earth ain't even gonna be round to see it

The Earth was never round to see it  :lol:

what do you mean? it didn't look round when you were landing in your spaceship? you're obviously not of this world.