According to a New Scientist article, it has been found that the motion of human sperm breaks Newton’s 3rd Law of Motion, i.e. the forward force on the sperm is greater than the reaction force of the sperm on the fluid it is swimming through.

There are also many other articles on-line with the same claim, e.g:
https://www.msn.com/en-us/news/technology/scientists-caught-sperm-defying-one-of-the-major-laws-of-physics/ar-AA1iJSnp

“Newton’s third law can be summed up as “for every action, there is an equal and opposite reaction”. It signifies a particular symmetry in nature where opposing forces act against each other. In the simplest example, two equal-sized marbles colliding as they roll along the ground will transfer their force and rebound based on this law.

However, nature is chaotic, and not all physical systems are bound by these symmetries. So-called non-reciprocal interactions show up in unruly systems made up of flocking birds, particles in fluid – and swimming sperm.”

I say this is nonsense, it has nothing to do with “unruly systems”. They have simply got their numbers wrong, or they are ignoring part of the reaction force.

Any comments?

The Rev Dodgson said:

According to a New Scientist article, it has been found that the motion of human sperm breaks Newton’s 3rd Law of Motion, i.e. the forward force on the sperm is greater than the reaction force of the sperm on the fluid it is swimming through.

There are also many other articles on-line with the same claim, e.g:
https://www.msn.com/en-us/news/technology/scientists-caught-sperm-defying-one-of-the-major-laws-of-physics/ar-AA1iJSnp

“Newton’s third law can be summed up as “for every action, there is an equal and opposite reaction”. It signifies a particular symmetry in nature where opposing forces act against each other. In the simplest example, two equal-sized marbles colliding as they roll along the ground will transfer their force and rebound based on this law.

However, nature is chaotic, and not all physical systems are bound by these symmetries. So-called non-reciprocal interactions show up in unruly systems made up of flocking birds, particles in fluid – and swimming sperm.”

I say this is nonsense, it has nothing to do with “unruly systems”. They have simply got their numbers wrong, or they are ignoring part of the reaction force.

Any comments?

If the 3rd law gets broken then nothing in mechanics works.

Do you happen to have the source paper?

The Rev Dodgson said:

Any comments?

Biology journalists can fuck right off.

dv said:

Do you happen to have the source paper?

These fellas https://journals.aps.org/prxlife/abstract/10.1103/PRXLife.1.023002 might do.

dv said:

Do you happen to have the source paper?

No, just the short article linked, and the even shorter New Scientist article.

dv said:

The Rev Dodgson said:

According to a New Scientist article, it has been found that the motion of human sperm breaks Newton’s 3rd Law of Motion, i.e. the forward force on the sperm is greater than the reaction force of the sperm on the fluid it is swimming through.

There are also many other articles on-line with the same claim, e.g:
https://www.msn.com/en-us/news/technology/scientists-caught-sperm-defying-one-of-the-major-laws-of-physics/ar-AA1iJSnp

“Newton’s third law can be summed up as “for every action, there is an equal and opposite reaction”. It signifies a particular symmetry in nature where opposing forces act against each other. In the simplest example, two equal-sized marbles colliding as they roll along the ground will transfer their force and rebound based on this law.

However, nature is chaotic, and not all physical systems are bound by these symmetries. So-called non-reciprocal interactions show up in unruly systems made up of flocking birds, particles in fluid – and swimming sperm.”

I say this is nonsense, it has nothing to do with “unruly systems”. They have simply got their numbers wrong, or they are ignoring part of the reaction force.

Any comments?

If the 3rd law gets broken then nothing in mechanics works.

My thoughts exactly :)

sigh

SCIENCE said:

dv said:

Do you happen to have the source paper?

These fellas https://journals.aps.org/prxlife/abstract/10.1103/PRXLife.1.023002 might do.

Shouldn’t have passed peer review.
PRX Life … I looked up its Journal Impact Factor and it doesn’t even have one.

dv said:

SCIENCE said:

dv said:

Do you happen to have the source paper?

These fellas https://journals.aps.org/prxlife/abstract/10.1103/PRXLife.1.023002 might do.

Shouldn’t have passed peer review.
PRX Life … I looked up its Journal Impact Factor and it doesn’t even have one.

Yeah we suppose this is one of the issues right here.

LOL

I’m often reminded of the ABC journo who did a piece about a local inventor who was talking about the room-temperature superconductors he had invented in his shed. Just went out and talked to the bloke and reported this news, dryly and uncritically, like it was a mildly interesting human interest story.

SCIENCE said:

dv said:

SCIENCE said:

These fellas https://journals.aps.org/prxlife/abstract/10.1103/PRXLife.1.023002 might do.

Shouldn’t have passed peer review.
PRX Life … I looked up its Journal Impact Factor and it doesn’t even have one.

Yeah we suppose this is one of the issues right here.

LOL

“Nothing in the physical universe makes sense anymore” should probably go to a more prestigious established journal.

Ye cannae change laws of physics.

Searching on flocking birds rather than sperm came up with:

https://www.quantamagazine.org/a-new-theory-for-systems-that-defy-newtons-third-law-20211111/

“For these unruly systems, statistical mechanics falls short in representing phase transitions. Out of equilibrium, nonreciprocity dominates. Flocking birds show how easily the law is broken: Because they can’t see behind them, individuals change their flight patterns in response to the birds ahead of them. So bird A doesn’t interact with bird B in the same way that bird B interacts with bird A; it’s not reciprocal. Cars barreling down a highway or stuck in traffic are similarly nonreciprocal. Engineers and physicists who work with metamaterials — which get their properties from structure, rather than substance — have harnessed nonreciprocal elements to design acoustic, quantum and mechanical devices.

Many of these systems are kept out of equilibrium because individual constituents have their own power source — ATP for cells, gas for cars. But all these extra energy sources and mismatched reactions make for a complex dynamical system beyond the reach of statistical mechanics. How can we analyze phases in such ever-changing systems?”

I hope it’s the reporter misunderstanding what the scientist guy told him.

Unruly reporting.

I think part of the problem is that even scientists talk as though “action” and “reaction” were two separate things, rather than different views of the same thing, which is an interaction between two objects.

The Rev Dodgson said:

Searching on flocking birds rather than sperm came up with:

https://www.quantamagazine.org/a-new-theory-for-systems-that-defy-newtons-third-law-20211111/

“For these unruly systems, statistical mechanics falls short in representing phase transitions. Out of equilibrium, nonreciprocity dominates. Flocking birds show how easily the law is broken: Because they can’t see behind them, individuals change their flight patterns in response to the birds ahead of them. So bird A doesn’t interact with bird B in the same way that bird B interacts with bird A; it’s not reciprocal. Cars barreling down a highway or stuck in traffic are similarly nonreciprocal. Engineers and physicists who work with metamaterials — which get their properties from structure, rather than substance — have harnessed nonreciprocal elements to design acoustic, quantum and mechanical devices.

Many of these systems are kept out of equilibrium because individual constituents have their own power source — ATP for cells, gas for cars. But all these extra energy sources and mismatched reactions make for a complex dynamical system beyond the reach of statistical mechanics. How can we analyze phases in such ever-changing systems?”

I hope it’s the reporter misunderstanding what the scientist guy told him.

I’m a reasonable man but these people need to get in the bin

dv said:

The Rev Dodgson said:

Searching on flocking birds rather than sperm came up with:

https://www.quantamagazine.org/a-new-theory-for-systems-that-defy-newtons-third-law-20211111/

“For these unruly systems, statistical mechanics falls short in representing phase transitions. Out of equilibrium, nonreciprocity dominates. Flocking birds show how easily the law is broken: Because they can’t see behind them, individuals change their flight patterns in response to the birds ahead of them. So bird A doesn’t interact with bird B in the same way that bird B interacts with bird A; it’s not reciprocal. Cars barreling down a highway or stuck in traffic are similarly nonreciprocal. Engineers and physicists who work with metamaterials — which get their properties from structure, rather than substance — have harnessed nonreciprocal elements to design acoustic, quantum and mechanical devices.

Many of these systems are kept out of equilibrium because individual constituents have their own power source — ATP for cells, gas for cars. But all these extra energy sources and mismatched reactions make for a complex dynamical system beyond the reach of statistical mechanics. How can we analyze phases in such ever-changing systems?”

I hope it’s the reporter misunderstanding what the scientist guy told him.

I’m a reasonable man but these people need to get in the bin

Strap them to the centrifuge:

Ah, A Plain Cartesian

SCIENCE said:

Ah, A Plain Cartesian

A cartesian diver

The Rev Dodgson said:

I think part of the problem is that even scientists talk as though “action” and “reaction” were two separate things, rather than different views of the same thing, which is an interaction between two objects.

Fine.

Just remember that “Action = Reaction” is statics, not dynamics. If your sperm is moving, then that’s dynamics not statics.

In dynamics, it resolves the law Action minus Reaction is rate change of Momentum.

In other words, in fluid dynamics the Navier-Stokes equations apply.
Now we need to be careful of laminar vs turbulent flow. For small objects such as sperm it’s laminar flow, so that’s OK.

But it isn’t the potential flow approximation to laminar flow because there is probably vortex shedding in flagellate swimming, like the vortex shedding we see from the Hawk Moth and Bumblebee.

mollwollfumble said:

The Rev Dodgson said:

I think part of the problem is that even scientists talk as though “action” and “reaction” were two separate things, rather than different views of the same thing, which is an interaction between two objects.

Fine.

Just remember that “Action = Reaction” is statics, not dynamics. If your sperm is moving, then that’s dynamics not statics.

In dynamics, it resolves the law Action minus Reaction is rate change of Momentum.

In other words, in fluid dynamics the Navier-Stokes equations apply.
Now we need to be careful of laminar vs turbulent flow. For small objects such as sperm it’s laminar flow, so that’s OK.

But it isn’t the potential flow approximation to laminar flow because there is probably vortex shedding in flagellate swimming, like the vortex shedding we see from the Hawk Moth and Bumblebee.

No, reaction = (sum of external reactions + inertial reaction) so Action = -Reaction applies in any inertial frame of reference.

Calculating the actions and reactions in a fluid becomes a little difficult, which is presumably where they went wrong, but it doesn’t mean things are “breaking Newton’s 3rd Law of Motion”.

The Rev Dodgson said:

mollwollfumble said:

The Rev Dodgson said:

I think part of the problem is that even scientists talk as though “action” and “reaction” were two separate things, rather than different views of the same thing, which is an interaction between two objects.

Fine.

Just remember that “Action = Reaction” is statics, not dynamics. If your sperm is moving, then that’s dynamics not statics.

In dynamics, it resolves the law Action minus Reaction is rate change of Momentum.

In other words, in fluid dynamics the Navier-Stokes equations apply.
Now we need to be careful of laminar vs turbulent flow. For small objects such as sperm it’s laminar flow, so that’s OK.

But it isn’t the potential flow approximation to laminar flow because there is probably vortex shedding in flagellate swimming, like the vortex shedding we see from the Hawk Moth and Bumblebee.

No, reaction = (sum of external reactions + inertial reaction) so Action = -Reaction applies in any inertial frame of reference.

Calculating the actions and reactions in a fluid becomes a little difficult, which is presumably where they went wrong, but it doesn’t mean things are “breaking Newton’s 3rd Law of Motion”.

Yeah But Why Admit Error When You Can Call Physics Wrong ¿