Can any object cause fluctuations in a magnetic field?

[Deleted member 690984]

Summary:: Can a moving object cause disruptions in a magnetic field that could be detectable?

Hello,

I was hoping someone could assist me on a query I have regarding disruptions in a magnetic field. For some context, I am creating a science fiction story which features a non-humanoid alien species. The alien has an extremely sensitive sense of magnetoreception (don't worry, this is not a biology question); since each location on the planet has a unique magnetic signature, the creatures form extremely complex and highly detailed magnetic maps of their environment to aid in navigation, not at all unlike homing pigeons or sharks. They also use this sense of magnetoreception to aid their otherwise poor proprioceptive sense (the creatures resemble octopuses with most of their neurons in their arms), as they use their detailed magnetic mapping to calculate their body's position relative to the magnetic field.

My question is this: these creatures are naturally deaf, so, given this keen sense of magnetoreception, would another animal moving nearby create *any* kind of fluctuation in the planet's magnetic field, no matter how small and insignificant, that these creatures could detect - for example, to avoid danger? What would be needed to cause such a fluctuation (again, no matter how minute, as the creatures only need to detect this locally, not over enormous distances) that they could pick up using this sense? Would you need magnetic materials present in the other animal in order to cause small fluctuations in the field they could pick up?

Any assistance that any of you can provide will be greatly beneficial!

 

[jim mcnamara]

Neurons - if your beasties have a brain and CNS - create a EM field that can be sensed by sharks and some kind of eels and lampreys on earth. So they could sense other fellow octo-monsters I would guess.

Movement at small velocities - that object is not a likely choice to generate a magnetic field. Other animals would be a better choice for a source. Magnetic ores also. Planetary magnetospheres are a good choice.

Pigeons can migrate using Earth's magnetic field for guidance, as another kind of example. A few bacteria species sense magnetic fields, too.

See: https://phys.org/news/2020-05-animals-earth-magnetic-field.html
For Earth animal version of your question.

 

[Jarvis323]

It is believed by some scientists that magnetoreception works at least in some cases through exploitation of quantum entanglement.

https://www.pbs.org/wgbh/nova/article/birds-quantum-entanglement/

Note: the article able has some outdated info. It says in it that there is no evidence that humans can sense magnetic fields, but about a month after the article was written, it was shown that humans can seem to sense magnetic fields.

https://www.sciencemag.org/news/2019/03/humans-other-animals-may-sense-earth-s-magnetic-field

It wouldn't be a stretch to give them some additional quantum sensing based abilities besides magnetoreception. I'm not an expert on quantum sensing, but I believe the possibilities are pretty expansive in theory. You could probably come up with some realistic enough way that they could sense movement.

​

Quantum Sensors have applications in a wide variety of fields including microscopy, positioning systems, communication technology, electric and magnetic field sensors, as well as geophysical areas of research such as mineral prospecting and seismology.[2] Many measurement devices utilize quantum properties in order to probe measurements such as atomic clocks, superconducting quantum interference devices, and nuclear magnetic resonance spectroscopy.[2][11] With new technological advancements, individual quantum systems can be used as measurement devices, utilizing entanglement, superposition, interference and squeezing to enhance sensitivity and surpass performance of classical strategies.

A good example of an early quantum sensor is an avalanche photodiode (ADP). ADPs have been used to detect entangled photons. With additional cooling and sensor improvements can be used where photomultiplier tubes (PMT) in fields such as medical imaging. APDs, in the form of 2-D and even 3-D stacked arrays, can be used as a direct replacement for conventional sensors based on silicon diodes.[12]

The Defense Advanced Research Projects Agency (DARPA) launched a research program in optical quantum sensors that seeks to exploit ideas from quantum metrology and quantum imaging, such as quantum lithography and the NOON state,[13] in order to achieve these goals with optical sensor systems such as lidar.[14][15][16]

For photonic systems, current areas of research consider feedback and adaptive protocols. This is an active area of research in discrimination and estimation of bosonic loss.[17]

Injecting squeezed light into interferometers allows for higher sensitivity to weak signals that would be unable to be classically detected.[3] A practical application of quantum sensing is realized in gravitational wave sensing.[18] Gravitational wave detectors, such as LIGO, utilize squeezed light to measure signals below the standard quantum limit.[19] Squeezed light has also been used to detect signals below the standard quantum limit in plasmonic sensors and atomic force microscopy.[20]

Quantum sensing also has the capability to overcome resolution limits, where current issues of vanishing distinguishability between two close frequencies can be overcome by making the projection noise vanish.[21][22] The diminishing projection noise has direct applications in communication protocols and nano-Nuclear Magnetic Resonance.[23][24]

Entanglement can used used into improve upon existing atomic clocks[25] or create more sensitive magnetometers.[26][27] Quantum radar is also an active area of research. Current classical radars can interrogate many target bins while quantum radars are limited to a single polarization or range.[28]

https://en.wikipedia.org/wiki/Quantum_sensor

 

[BillTre]

There are a lot of animals that already can sense electrical signals in their environment. These are in the form of fluctuating signals. Static signals are not so well detected, probably not so important (since it is probably not a food opportunity nor a threat).
I am thinking here that this relates to your basic idea because a changing electrical field will also have a magnetic component (electromagnetism).

These animals make different uses of these sensory abilities.

Some passively listen to their environment for various reasons, like some sharks or rays (related) have a passive electrosensory system. These predators can pick up the electrical signal of the heart beat of small animals buried in the sand from a foot or more away. The heart beat produces a sudden fluctuation in the local electrical field, due to the ion movements, going the short distances of a cell's membrane. Owls do this with sound.

Some are actively electrosensing (or electroreceptive). Like a radar or sonar system, they send out a defined pulse of energy. Using the same kind of electroreceptor cells as the passively electrorecepetive animals use, they sense how the electric field in which they reside responds. This kind of information allows them to map things around them in the water, even if they are not actively making electric signals. They can sense differences in conductivity of the medium (rock vs. salty water) and get an idea of what shape they are. Echolocating bats do this with sound.
This sounds more like what you are interested in, in your story.

This is different from knowing where you are anywhere on the globe. That would be more on the scale of a cueing system used by animals doing long distant migrations (like some birds).
Small bits of magnetite have been found in various parts of nervous systems, so a sensory role has been proposed, but not to my knowledge, been well demonstrated. Several other cues are also available to guide long distance migrations. It is certainly not clear that just a static magnetic field is solely responsible for their migratory abilities. What migrating animals use to navigate are probably a series of cues, concerning which way to go and where to turn or stop.

Even if you did have a refined ability to sense these unchanging magnetic fields, I not sure that you could, without at least one other orientating cue (like seeing the north star?), determine a single position on the globe. All an individual organism will have to go on from a magnetic signal is its strength and the animals orientation to the field. It needs additional cues.

they use their detailed magnetic mapping to calculate their body's position relative to the magnetic field.

These things sound like they would be highly susceptible to to disruption by local varying fields (keep away from microwave ovens!). This could be a strategy for either a predator to disable a prey or for a preys predator defense system.

What you are describing, sounds like a second independent (from earth) origin of life, as a system of chemicals.
I have read a book once that had aliens that were of some vaguely described self-sustaining electromagnetic entity. They lived in the highly charged electromagnetic environment of a star's plasma. Your critter's (so overpoweringly focused on magnetic sensing) sound better suited to that kind of environment.
This would be more of an electromagnetic life form than a chemically based one.

 

[Rive]

would another animal moving nearby create *any* kind of fluctuation in the planet's magnetic field

As long as the permeability of such animal is sufficiently different from the permeability of the environment, it would.
The problem is, that difference in permeability would be very small: evolution would just erase such animals, not long after the invention of predation.

I think it would be better to go with the setup @BillTre hinted: for close range 'danger' sense electromagnetism is a far more realistic choice.

these creatures are naturally deaf

Sorry, but I think that one is an absolute story killer.

 

[Deleted member 690984]

Wow, some fantastic responses here! I'll get to each one individually shortly (working at the moment). Thanks folks!

 

[Deleted member 690984]

There are a lot of animals that already can sense electrical signals in their environment. These are in the form of fluctuating signals. Static signals are not so well detected, probably not so important (since it is probably not a food opportunity nor a threat).
I am thinking here that this relates to your basic idea because a changing electrical field will also have a magnetic component (electromagnetism).

These animals make different uses of these sensory abilities.

Some passively listen to their environment for various reasons, like some sharks or rays (related) have a passive electrosensory system. These predators can pick up the electrical signal of the heart beat of small animals buried in the sand from a foot or more away. The heart beat produces a sudden fluctuation in the local electrical field, due to the ion movements, going the short distances of a cell's membrane. Owls do this with sound.

Some are actively electrosensing (or electroreceptive). Like a radar or sonar system, they send out a defined pulse of energy. Using the same kind of electroreceptor cells as the passively electrorecepetive animals use, they sense how the electric field in which they reside responds. This kind of information allows them to map things around them in the water, even if they are not actively making electric signals. They can sense differences in conductivity of the medium (rock vs. salty water) and get an idea of what shape they are. Echolocating bats do this with sound.
This sounds more like what you are interested in, in your story.

This is different from knowing where you are anywhere on the globe. That would be more on the scale of a cueing system used by animals doing long distant migrations (like some birds).
Small bits of magnetite have been found in various parts of nervous systems, so a sensory role has been proposed, but not to my knowledge, been well demonstrated. Several other cues are also available to guide long distance migrations. It is certainly not clear that just a static magnetic field is solely responsible for their migratory abilities. What migrating animals use to navigate are probably a series of cues, concerning which way to go and where to turn or stop.

Even if you did have a refined ability to sense these unchanging magnetic fields, I not sure that you could, without at least one other orientating cue (like seeing the north star?), determine a single position on the globe. All an individual organism will have to go on from a magnetic signal is its strength and the animals orientation to the field. It needs additional cues.These things sound like they would be highly susceptible to to disruption by local varying fields (keep away from microwave ovens!). This could be a strategy for either a predator to disable a prey or for a preys predator defense system.

What you are describing, sounds like a second independent (from earth) origin of life, as a system of chemicals.
I have read a book once that had aliens that were of some vaguely described self-sustaining electromagnetic entity. They lived in the highly charged electromagnetic environment of a star's plasma. Your critter's (so overpoweringly focused on magnetic sensing) sound better suited to that kind of environment.
This would be more of an electromagnetic life form than a chemically based one.

This is a great response - so thank you first. You raise a good point re the magnetic sensing, I added that in as these creatures are actually based on octopuses, which have a very poor sense of self-perception due to their heavily decentralised nervous system - as an example, the only way they know what movements their body has made is by observing their arms with their eyes. They secrete a chemical so that their own suckers don't latch onto other arms.

Rather than having an over-developed magnetoreceptive sense (e.g. to control their sense of self-perception), I feel like the electrosensing by sending out a pulse of energy to map their environment may be better, such as a powerful sonic vocalisation of some kind, but rather than "hearing" like we do, they use their receptor cells to make a detailed map of their environment.

As you say otherwise such a heavily developed magnetic sensing seems more focused for an electromagnetic environment. I did have the idea of a plasma-based lifeform found inside a star as it happens, so it may be better for that.

 

[Deleted member 690984]

Sorry, but I think that one is an absolute story killer.

Curious, why do you think so? After all, not every creature has a sense of hearing. Although if I'm now giving them an electroreceptive sense, that's analogous to a sense of hearing.

 

[Rive]

Curious, why do you think so? After all, not every creature has a sense of hearing.

But you depicted a creature which can sense minuscule changes in magnetic field as primary sense. No way that the evolution of such creature would omit 'listening' to rhythmic changes in magnetic fields. Especially, since you included 'danger' sensing.

Just as you wrote:

I feel like the electrosensing by sending out a pulse of energy to map their environment may be better, such as a powerful sonic vocalisation of some kind

'Listening' to rhythmic changes - that's hearing. Of some kind.
It's especially a tricky stuff since with this setup about magnetic: possibly electromagnetic sensing all the world is a stage microphone...

 

[Deleted member 690984]

But you depicted a creature which can sense minuscule changes in magnetic field as primary sense. No way that the evolution of such creature would omit 'listening' to rhythmic changes in magnetic fields. Especially, since you included 'danger' sensing.

Just as you wrote:

'Listening' to rhythmic changes - that's hearing. Of some kind.
It's especially a tricky stuff since with this setup about magnetic: possibly electromagnetic sensing all the world is a stage microphone...

That's true, they will have a form of 'hearing', just not necessarily sonic-based hearing that we have - that's more what I was getting at by saying they were deaf. Deaf as we would perceive hearing. I've decided to go with a passive electroreception so they can sense the bioelectric fields given off by other creatures, but again this would only give them a picture of their environment (beyond what they can see with their eyes) in terms of what creatures are around them.

Would it be evolutionarily believable to give them a form of echolocation to create maps of their environment as well as electroreceptive, or just one or the other? I'm just thinking that electroreception wouldn't be able to tell them if, say, a tree is falling, because they don't have sonic-based hearing. We hear a tree crack and begin to fall so we know to run away, but if they can't detect something like that they'd just get squashed. Or would it make more sense for them to also be magnetoreceptive to create maps, since they are already electroreceptive, and magnetism and electricity are linked?

 

[Deleted member 690984]

Does anyone have any thoughts on the above post?