Physicists create an object with negative mass!

Original post by Fullofsurprises

If this is true, then everyone will have to be really positive all the time

How will you manage? :smile:

Reply 22

Original post by Mathemagicien

In relativistic quantum field theories, mass usually shows up squared. So although there are interesting things that can happen when mass changes sign, the thing that "breaks" relativity (i.e., FTL particles) is imaginary mass, so that mass squared is negative.

Do you think it might be possible to give a gentle definition to what mass is? I had assumed it is just a proxy for matter but then negative mass would imply negative matter and that isn't very meaningful. I'm struggling to understand the concept. Mass is a scalar so the sign doesn't imply a directionality. Then what is it and what happens after zero mass that is opposite to positive mass?

Reply 23

Kyx

OP

6

Original post by Mathemagicien

I think the important thing to remember is that it doesn't actually have negative mass, it only acts as though it does in certain circumstances.

I have no idea how this negative mass effect was created, but there are some quantum theory related things iirc, so I imagine it accelerates towards the Earth as per usual.

Maybe. But even if it did actually have negative mass, it would fall towards the earth?

Posted from TSR Mobile

Reply 24

Original post by Mathemagicien

I don't know what mass is. I am no expert. Apparently there are at least two types - inertial mass, and gravitational. For all I know I am talking absolute :innocent:

. Take my 'knowledge' with a few tonnes of salt.

I asked my physics teacher what mass is and he threw a pen at me. It wasn't even a projectiles lesson that time!

Reply 25

Original post by Kyx

GMm/r^2

If one of the masses is negative, then the force would be in the other direction

But then it would accelerate on the opposite direction to that force which is straight down, so it would obey it...

Posted from TSR Mobile

Original post by Mathemagicien

I think the important thing to remember is that it doesn't actually have negative mass, it only acts as though it does in certain circumstances.

I have no idea how this negative mass effect was created, but there are some quantum theory related things iirc, so I imagine it accelerates towards the Earth as per usual.

Guys, it's not negative mass.

Look up effective mass. Read the actual paper published (you should have access if you're a uni student?).

Reply 26

Kyx

OP

6

Original post by Athematica

I asked my physics teacher what mass is and he threw a pen at me. It wasn't even a projectiles lesson that time!

Ask him if negative mass is possible. If he says no, show him this. If he says yes, show him this. If he says idk, show him this :tongue:

Posted from TSR Mobile

Reply 27

Kyx

OP

6

Original post by hezzlington

Guys, it's not negative mass.

Look up effective mass. Read the actual paper published (you should have access if you're a uni student?).

Not yet I'm not :frown:

But now we are theorising about actual negative mass :tongue:

Posted from TSR Mobile

Reply 28

Original post by Kyx

Not yet I'm not :frown:

But now we are theorising about actual negative mass :tongue:

Posted from TSR Mobile

Have fun with that!!

Reply 29

Original post by Kyx

Physicists have created a fluid that accelerates in the opposite direction to a force that is applied to it. This can be explained by Newton's laws of motion provided the mass is negative, just like charge can be positive or negative

Source: Physical Review Letters, BBC news

Posted from TSR Mobile

I read the article and I'm no physicist, but it doesn't exactly sound like they've created an 'object' with negative mass. What it sounds like is that they have manipulated some incredibly cold atoms with lasers so that they exhibit some strange properties similar to what negative mass might look like in a theoretical way. Not quite the same thing. :holmes:

I think.

Reply 30

Original post by Mathemagicien

That sounds similar to some things I used to hear about in New Scientist. It certainly isn't anything to be too excited about - well, more exciting than celebrities and their new drama, but less than an actual breakthrough.

Yes, the ratio between genuine major scientific breakthroughs and media coverage of supposed major scientific breakthroughs is about 1:25000 or something like that.

What was the last genuine science story? Graphene?

Reply 31

Original post by Fullofsurprises

I read the article and I'm no physicist, but it doesn't exactly sound like they've created an 'object' with negative mass. What it sounds like is that they have manipulated some incredibly cold atoms with lasers so that they exhibit some strange properties similar to what negative mass might look like in a theoretical way. Not quite the same thing. :holmes:

I think.

Almost, it's not even 'negative mass'.

Negative mass is still a hypothetical concept that's never been observed in a lab. This was a fluid displaying negative effective mass at a particular state of matter (when objects get very, very cold - odd things start to happen).

Reply 32

Original post by Fullofsurprises

Yes, the ratio between genuine major scientific breakthroughs and media coverage of supposed major scientific breakthroughs is about 1:25000 or something like that.

What was the last genuine science story? Graphene?

Graphene?!!!

What about the new planets??

:frown:

k den

Original post by hezzlington

Graphene?!!!

What about the new planets??

:frown:

Yes, those are very cool. But I thought they'd been discovered for quite a while now and are therefore basically an older story than graphene?

Reply 35

Original post by Mathemagicien

Probably the coverage of Darwin's returns from his voyages to foreign lands.

Haha. Did that get publicised at the time, or was it only much later that Darwin became a thing?

Reply 36

Original post by Fullofsurprises

Yes, the ratio between genuine major scientific breakthroughs and media coverage of supposed major scientific breakthroughs is about 1:25000 or something like that.

What was the last genuine science story? Graphene?

They created metal hydrogen in a Harvard lab recently. It can theoretically be used as a superconductor in solid form and therefore be used for power lines that lose no power when transporting electricity.

Reply 37