Does Negative Mass Exist in the Universe?

[arivero]

Guys this isn't very complicated.. Eqns of motion of a negative mass particle (-m)

F = (-m) a = G (-m) m /r^2 ==> a = GM/r^2. It accelerates towards a positive mass particle, just as normal mass does.

What about a negative length too?


it would change the sign of the aceleration. you can postulate that negative mass sees negative leghts and save the day

 

[Severian]

I am afraid I don't have the stamina to read the whole thread, but I thought I would make a comment anyway.

In Quantum Field Theories negative mass doesn't make much difference. For a scalar (spinless) object, the expression in the Lagrangian (ie. the physical description) is alway m^2, so if m<0 you get the same thing. Therefore whether or not the mass is positive or negative is just a matter of definition.

For a fermion, the mass in the Lagrangian is linear but you can just redefine your fermion field to make it positive.

As for GR, the important quantity is the energy, not the mass, so the appropriate question would be, 'are there negative energy states?'

In other words, I don't think there is any reason why you couldn't have negative mass, but it would behave exactly the same as what we already see, and would just be a definition. A more interesting question is 'are there imaginary masses'?

 

[Rade]

...A more interesting question is 'are there imaginary masses'?

By imaginary do you mean masses that mathematically can only be described by (i) as a type of complex number superposition between real + imaginary, where i = the square root of -1 ?

 

[Severian]

By imaginary do you mean masses that mathematically can only be described by (i) as a type of complex number superposition between real + imaginary, where i = the square root of -1 ?

Yes, so that the square of the mass is negative, and the particle is a tachyon.

 

[Norman]

Yes, so that the square of the mass is negative, and the particle is a tachyon.

Not really all that interesting since it has been rigorously proven that you cannot send a "message" with a tachyon. Check out john baez's site for a great explanation of it.

 

[selfAdjoint]

Not really all that interesting since it has been rigorously proven that you cannot send a "message" with a tachyon. Check out john baez's site for a great explanation of it.

WIth all respect to Professor Baez, the history of "rigorous no-go theorems" in physics is not too magnificent.

 

[Norman]

WIth all respect to Professor Baez, the history of "rigorous no-go theorems" in physics is not too magnificent.

A very good point that made me smile a little also at how cavalier my statement was. But the experimental search for the tachyon has not been too magnificent either... so I suppose we will wait.

 

[Severian]

Not really all that interesting since it has been rigorously proven that you cannot send a "message" with a tachyon. Check out john baez's site for a great explanation of it.

It is interesting because of the consequences the presence of a tachyon would have for the stability of the vacuum.

 

[actionintegral]

Do not loose track of reality. According to David Gross (Nobel Luareate) We are in a state of confussion...these equations tell us nothing about where space and time come from and describe nothing we would recognize. We are missing something fundamental.
What we know is a collection of mathematical short cuts which predict. we know not why or how.

I came across this post out-of-context. I would like to know more about it.

 

[Nexus555]

Here's something interesting to think about. If negative mass did exist, it would probably be nearly impossible to identify in the lab. Think about it, negative mass means negative gravity, which means something with negative mass wouldn't attract matter, it would repel it... To me that means that we won't be able to find it anytime soon, because it's repel away from positive gravity...

I'm very doubtful and unsure about dark energy/matter at this point, but a good idea would be that the dark energy and matter is actually the negative mass/energy in the universe, and it may cause the universe to expand because it's reactions with positive mass and energy. Maybe that's why it "spreads" too, because when it comes on contact with new space, it attracts the NEGATIVE mass and energy and continues to repel positive mass and energy...

Just an assumption.

 

[Haelfix]

"In other words, I don't think there is any reason why you couldn't have negative mass, but it would behave exactly the same as what we already see, and would just be a definition. A more interesting question is 'are there imaginary masses'?"

It wouldn't make much of a difference for electroweak or strong force interactions, but it very much would for gravity. Since the equations of motion for a massless spin2 gauge field just reduces to Newtons law in the nonrelativistic limit...

 

[Hans de Vries]

"In other words, I don't think there is any reason why you couldn't have negative mass, but it would behave exactly the same as what we already see, and would just be a definition. A more interesting question is 'are there imaginary masses'?"

It wouldn't make much of a difference for electroweak or strong force interactions, but it very much would for gravity. Since the equations of motion for a massless spin2 gauge field just reduces to Newtons law in the nonrelativistic limit...

Imaginary masses would flip the sign in Klein Gordon:

\partial^2_t \psi - \partial^2_x \psi \ =\ m^2 \psi

Which says as much as: "The acceleration of psi away from zero is
proportional to psi..." This gives us the Bessel I1 and K1 functions
in the space-time propagator instead of the usual J1 and Y1 from
which the Bessel I1 nicely shows the explosive result...

http://mathworld.wolfram.com/ModifiedBesselFunctionoftheFirstKind.html
http://mathworld.wolfram.com/ModifiedBesselFunctionoftheSecondKind.html

(Unless you have a λ which holds it back at 4th order of course.)

The Bessel K1 is not so explosive but it still haunts us today as the thing
which is supposed to cause propagation outside the light-cone over a
range of 1/m, like in P&S (2.52) and Zee (I.23). This "leaking range"
would be infinite in the limit case of massless particles. Simulations
however don't show any propagation outside the light-cone at all.

This story goes back to RF's "Theory of positrons, 1949" where he
found the Hankel functions in the tables instead of the separate Bessel J
and Bessel Y functions. The Hankels are the complex combinations
I1 + i Y1 and I1 - i Y1 and the Y1 becomes our K1 outside the
light-cone where the argument becomes imaginary...Regards, Hans

 

[petm1]

does negative mass exists?

I would think that negative mass as it relates to us, would be the wake of our movement through existence, we are always at the flux point between where we are and where we have been and negative mass being that part of space where mass was, after it has moved on. I would think that photons show us negative matter at all times, and the only time you sense positive mass is when you touch it.