negative mass

[HG Bells]

lets suppose that some one found that there was a negative mass particle then we could have space ships with no net mass. but how how do you accelerate an object with no mass? any ideas

[RyanJ]

lets suppose that some one found that there was a negative mass particle then we could have space ships with no net mass. but how how do you accelerate an object with no mass? any ideas

 

It would be very interesting for sure. Have a look at Newton's laws of motion and plus in some negative mass and speed and you'll see some interesting results.

 

it seems that the harder you push an object with negative mass the more it would push back so you'd actually have to pull it to make it move. Not at all practical nor useful. That's how I interpret it anyway.

[Sisyphus]

 

it seems that the harder you push an object with negative mass the more it would push back

 

That's what mass does!

[RyanJ]

That's what mass does!

 

I think I phrased that rather badly

 

I was thinking more along the lines of [math]F=ma, F=-1*12, F=-12N[/math]

 

Better put the object would accelerate in the opposite direction to which it is pushed.

 

Sorry if I put that badly. I should have thought it through a little better

[Severian]

There is actually no such thing as negative mass by construction.

 

If you mean negative gravitational mass (which is not what the original post is suggesting) then you can't have it because of the structure of GR.

 

If you mean negative inertial mass (which appears to be what is intended in the OP) you either can't have them, or always have them, depending on your point of view. There are two types of masses in our fundamental theories - bosonic and fermion masses. Bosonic masses (like for the Z-boson or the Higgs) always appear in the equations as their square [math]m^2[/math] so having negative mass is exactly the same as a positive mass (you couldn't tell the difference, so there is no difference).

 

For fermions (eg the electron) it is similar - although the mass now appears unsquared, one can always redefine the fermion fields themselves (actually a rotation in the complex plane) to absorb the minus sign. So again, there is no difference.

[BenTheMan]

Severian---perhaps he meant a tachyon?

[pioneer]

Negative mass would be the opposite of positive or regular mass. So if we had half negative and half positive mass we would have zero mass. For space travel, we build the inside of regular mass for living quarters, and the shell of negative mass, so it adds to zero mass. This way the entire composite would be able to travel at C due to zero mass. At C the positive mass would increase to infinity but the negative mass to negative infinity so that there is not net use of energy while we travel at C. This is all well and good ,but how would you make negative mass?

 

If we move positive or regular mass we need to add energy. To make negative mass we would need to take away energy. Since mass can exist down to absoute zero, we would have to break that barrier into the negative side of abolute zero so we can generate negative mass/energy. This is all done in play since we can't even reach absolute zero yet.

[BenTheMan]

pioneer---

 

The point severian made is that there is no such thing as negative mass---a suitable field redefinition always gets rid of it.

 

On the other hand, people have thought about tachyons, which have (effectively) an imaginary mass.

[pioneer]

I know there is none. I was simply working the assumption that there was to see where the logic took me. I was surprised by minus degrees Kelvin.

[alan2here]

1. I'm in space pushing something with a mass of 1 forward and it's pushing me 1 backwards and we float apart.

 

2. I'm in space pushing something with a mass of -1 forward and it's pushing me -1 backwards and we float together and nether one of us moves anywhere.

 

3. You would have to suck it along? possibly there is a flaw in my logic of 3 but I cant work it out, someone else rewrite 3 if it doesn't make any sense.

[HG Bells]

 

For fermions (eg the electron) it is similar - although the mass now appears unsquared, one can always redefine the fermion fields themselves (actually a rotation in the complex plane) to absorb the minus sign. So again, there is no difference.

 

but Severian by your own argument there is negative mass

 

its just that we use mass the same way we use AC electricity(in electricity there is negative 110V then positive 110V and the net is 0 but we use it as 110V) same with the mass we are only using the absolute value of it and not the positive value so then there must be a way to use the negative

[Severian]

That was why I said: "either can't have them, or always have them, depending on your point of view."

 

But since these equations I am talking about are the fundamental Lagrangians, and there is no observable difference, there can be no observable difference in any process. So there can be no "way to use" them at all.