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Royal Navy says quantum navigation test a success

thequantuminsider.com

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Re: Royal Navy says quantum navigation test a success

#91

Post by dumpsterdiver »

sph wrote: post #76
dumpsterdiver wrote: post #56

Earlier quoted context omitted.

[flagged]

> any stable solar system capable of sustaining life will emit a steady heartbeat, just like a living being What do you mean? What would be the source of the regular wave-like signal, and why only systems with life have one? Do you mean that actual hearts beating create gravitational waves?

> What do you mean? What would be the source of the regular wave-like signal

The source of the signal would be a solar system that contains planets in a stable enough orbit to harbor life.

> and why only systems with life have one?

Solar systems that harbor life (our own, for example) are not the only stable solar systems. A stable solar system is however required to be the genesis grounds of life as we understand it, otherwise the building blocks of such potential life would be swallowed in the chaos and heat.

Re: Royal Navy says quantum navigation test a success

#92

Post by andromeduck »

layer8 wrote: post #89
andromeduck wrote: post #31

Looks like what's happening is they've found a way to use BSEs [1] to measure small variations in the earth's gravity caused by undersea terrain, probably so that they can then use existing satelite measured data [2], to recover absolute position via Terrain Contour Matching [3] like a gulf war tomahawk missle. Edit: Seems like there's another company that's doing the same thing [4] with BSEs [5]. [1] https://physics…

What does BSE stand for? Your link doesn’t mention it.

Ahh brain fart, supposed to be BECs

https://www.livescience.com/54667-bose-einstein-condensate.h...

Re: Royal Navy says quantum navigation test a success

#94

Post by JumpCrisscross »

otikik wrote: post #54
jchallis wrote: post #13

This is the most obvious practical application of my PhD topic. A Bose Einstein Condensate is an extremely sensitive detector of gravity- a nuclear submarine could use it to make an ultra-accurate map of the world based on variations in the gravitational constant g. This would remove one of the primary reasons subs need to surface , in order to GPS lock. It’s a naval chart that would not require surfacing. A French p…

A submarine itself is quite massive, and has big moving parts (e.g. the rotor). The crew has less mass, but it would be very close, and also in constant movement. Wouldn’t this interfere with those measurements? Would they need to stop the engine and play “frozen TikTok” while the measurement device is active?

> Wouldn’t this interfere with those measurements

Towed sensors and multiple passes over known calibration zones?

Re: Royal Navy says quantum navigation test a success

#95

Post by krisoft »

jofer wrote: post #84
jchallis wrote: post #13

This is the most obvious practical application of my PhD topic. A Bose Einstein Condensate is an extremely sensitive detector of gravity- a nuclear submarine could use it to make an ultra-accurate map of the world based on variations in the gravitational constant g. This would remove one of the primary reasons subs need to surface , in order to GPS lock. It’s a naval chart that would not require surfacing. A French p…

It's somewhat unlikely (but not impossible) that this method is based on navigating by matching patterns of the shape of the geoid (aka variations in g). We need accurate maps of the geoid for a lot of different reasons. (Military as well as civilian. Potential fields geophysics is super useful for all kinds of different geologic use cases, and regardless, if you want to target an ICBM, you need an accurate geoid.) H…

> The biggest issue is that you also need to know absolute elevation very precisely to use the measurement of g that you get.

I don't think so. What you are saying is true if for some reason you want to work with absolute values, but nobody would do that. You measure many data points as your submarine flies over the landscape for a time, and then you match the measured curve with predicted curves from bathymetric maps. This is an optimisation problem where you try to find the best match. Precise elevation is an output from this process not an input requirement.

> but when things don't vary much (i.e flat topography and not a ton varying geologically), you don't have much of a unique signal to match to

100%. This is also true for cruise missiles which fly by TERCOM[1]. And there is an interesting consequence to it. Submarines and cruise missiles don't just bumble around randomly. The navigators also know this limitation so they set trajectories which plays to their strength. In the case of the cruise missile planners they have tools to evaluate the navigational quality of a terrain contour matching algorithm over a proposed trajectory with Monte Carlo methods. Probably submariners have the same.

This means in practice you can know that the submarines are more likely to take certain routes. They will prefer approaching from hilly terrain over flat, but also over extended flat areas they will prefer to overfly butes to regain navigational accuracy. This of course won't tell you precisely where the submarine is, but can help an adversary more economically allocate their ASW assets.

> At any rate, it's a very useful tool for many other things, but I'm skeptical it could be turned into a precise navigational aid

Yeah. I mean I heard that people proposed to make measurements of stars to find your location. The fools. Haven't they heard of clouds? Sometimes you can't see as far as your own nose for days.

Every navigational system ever devised have limitations and peculiarities. If you are comparing gravitational tercom with the ease and quality and simplicity of GPS then of course it will look crude and cumbersome. But of course GPS adds other complications and dangers to the life of a submariner. Used well, and in the right circumstances it can be potentially very valuable technique.

1: https://en.wikipedia.org/wiki/TERCOM

Re: Royal Navy says quantum navigation test a success

#96

Post by sgt101 »

kebman wrote: post #30
rocqua wrote: post #25

I'm surprised we don't see more military research for SAT-NAV alternatives. In any big conflict SAT-NAV is trivial to turn off. If you can still position yourself and your enemy can't, that is an enormous advantage in targeting, logistics, coordination, and situational awareness. Seems like a no-brainer.

You're probably surprised that you don't see it, because it's top secret. Here's an example of something you don't hear about: AI Assisted Battlefield Tactics. While I've never heard of it (certainly not in the press), I simply assume that they're doing research on it. I base this assumption on the AlphaStar AI from DeepMind that would completely pawn Grand Masters in the game of StarCraft 2. While AlphaStar is obvio…

Acushully...

There is a very specific problem - the simulation speed problem - that is in the way.

For games RL agents can be trained by running billions of adversarial simulations. Set up a battle between two agents and reward the one that wins, try variations and repeat, and repeat, and repeat. The trick is to manage the search process so as to not waste time on strategy branches that won't get anywhere, but the idea is very simple.

Unfortunately for things like real world conflict the simulations aren't that representative of what really happens, they are also really really really really complex and slow, and so finding wining strategies is a bit hard.

Re: Royal Navy says quantum navigation test a success

#97

Post by mytailorisrich »

julienfr112 wrote: post #44
jchallis wrote: post #13

This is the most obvious practical application of my PhD topic. A Bose Einstein Condensate is an extremely sensitive detector of gravity- a nuclear submarine could use it to make an ultra-accurate map of the world based on variations in the gravitational constant g. This would remove one of the primary reasons subs need to surface , in order to GPS lock. It’s a naval chart that would not require surfacing. A French p…

Is the gravity really constant ? I mean, big chunk of lava moving with different concentration of iron would make it change, wouldn't it?

No, as the parent said it isn't. This is why you can create a map of the variations like this one: https://svs.gsfc.nasa.gov/11234

Re: Royal Navy says quantum navigation test a success

#98

Post by aaron695 »

andromeduck wrote: post #31

Looks like what's happening is they've found a way to use BSEs [1] to measure small variations in the earth's gravity caused by undersea terrain, probably so that they can then use existing satelite measured data [2], to recover absolute position via Terrain Contour Matching [3] like a gulf war tomahawk missle. Edit: Seems like there's another company that's doing the same thing [4] with BSEs [5]. [1] https://physics…

> measure small variations in the earth's gravity

This would be incorrect.

It is just a very accurate, unproven in the field, accelerometer.

https://www.youtube.com/watch?v=XwKKOPd-5cU - "Royal Navy's experimental ship carries out first trial of quantum navigation system"

"The quantum accelerometer uses ultracold atoms to make highly accurate measurements. When cooled to extremely low temperatures the atoms start to display their ‘quantum’ nature, resulting in wave-like properties. As the atoms move through the sensor, an ‘optical ruler’ is formed by using a series of laser pulses. This allows the acceleration of the atoms to be precisely measured."

Re: Royal Navy says quantum navigation test a success

#99

Post by alexpotato »

jchallis wrote: post #13

This is the most obvious practical application of my PhD topic. A Bose Einstein Condensate is an extremely sensitive detector of gravity- a nuclear submarine could use it to make an ultra-accurate map of the world based on variations in the gravitational constant g. This would remove one of the primary reasons subs need to surface , in order to GPS lock. It’s a naval chart that would not require surfacing. A French p…

> a nuclear submarine could use it to make an ultra-accurate map of the world based on variations in the gravitational constant g

I believe in the book version of the Hunt for Red October by Tom Clancy, they mention that the Soviets did something similar but using a magnetometer.

Super cool to see the newest versions of this are going from sci-fi to fact.

Re: Royal Navy says quantum navigation test a success

#100

Post by jofer »

krisoft wrote: post #95
jofer wrote: post #84

Earlier quoted context omitted.

It's somewhat unlikely (but not impossible) that this method is based on navigating by matching patterns of the shape of the geoid (aka variations in g). We need accurate maps of the geoid for a lot of different reasons. (Military as well as civilian. Potential fields geophysics is super useful for all kinds of different geologic use cases, and regardless, if you want to target an ICBM, you need an accurate geoid.) H…

> The biggest issue is that you also need to know absolute elevation very precisely to use the measurement of g that you get. I don't think so. What you are saying is true if for some reason you want to work with absolute values, but nobody would do that. You measure many data points as your submarine flies over the landscape for a time, and then you match the measured curve with predicted curves from bathymetric map…

> What you are saying is true if for some reason you want to work with absolute values, but nobody would do that. You measure many data points as your submarine flies over the landscape for a time, and then you match the measured curve with predicted curves from bathymetric maps.

The variations due to changes in elevation are orders of magnitude larger than the variations you're relying on using for navigation. Distance from the center of the Earth is the primary signal you're measuring, for better or worse. It's not just relative vs absolute. You can probably assume the sub isn't changing depth rapidly and ocean currents are long wavelength, which would allow relative measurements to be somewhat feasible.

However, nothing about this requires a new quantum sensor. Ship-borne gravity anomaly measurements have been around for half a century. The previous methods are more than precise enough. In fact, they were done on submarines first before ships - it's easier to measure without waves.

What's triggering this now? Something doesn't add up... If it were purely based on using gravity anomaly along track measurements as a "fingerprint", it wouldn't need a new sensor. There's likely another mechanism they're using or they're using it for other reasons in addition to navigation.

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