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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

#151

Post by bequanna »

bluGill wrote: post #138
beambot wrote: post #117

Earlier quoted context omitted.

Let's use a magnetometer as an example. Inertial navigation system (INS) is just using the magnetometer as a compass, so errors in bearing accumulate over time. Instead, if you built a map of magnetic field strength, the slight spatial variation of field strength would let you precisely localize on the map. In robotics parlance, this is the difference between dead reckoning versus SLAM (simultaneous localization and…

The earths magnetic field is not constant. I don't know how much it changes, but I know magnetic north drifts a bit every year. And every once in a while the field reverses (IIRC we are like 10k years overdue for a reversal if we read the history of them right - a lot of guesses go into that of cousre)

Right, but it seems it is constant enough in the near term for practical purposes.

Re: Royal Navy says quantum navigation test a success

#152

Post by dumpsterdiver »

sethammons wrote: post #109
dumpsterdiver wrote: post #91

Earlier quoted context omitted.

> 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…

How does stability lead to a wave? We can see wobble in stars to know they are getting tugged by planets. Are you expecting similar with gravity? I'm not a physicist nor astronomer. I wouldn't expect any gravity waves as I'd expect the star system to have a center of mass that stays in roughly the same space.

> How does stability lead to a wave?

All gravitational events lead to a wave. A system emitting stable waves creates a "pattern".

Re: Royal Navy says quantum navigation test a success

#153

Post by awesometech »

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…

Submarines do not have to surface to get a GPS lock.

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

"On the surface or at periscope depth, submarines have used these methods to fix their position"...GPS being one of them.

A submarine can also navigate by the stars without surfacing.

https://www.usni.org/magazines/proceedings/2021/october/navi...

"This is precisely the information required by the traditional method of celestial navigation, and it is accomplished without the need to surface or use a sextant!"

Re: Royal Navy says quantum navigation test a success

#154

Post by Rygian »

fho wrote: post #143
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…

May I ask: how sensitive? Sensitive enough to, say, detect the movement of something moving at a known frequency on the other side of the planet? Are we on the edge of gravitation based communication channels?

I would wonder how massive the thing on the other side of the planet has to be, in order to be detectable.

The more mass necessary, the more energy you'll need to send messages.

Unless the detection is extremely accurate, you would be better off spending that energy in electromagnetic radiation that bounces off the atmosphere.

Re: Royal Navy says quantum navigation test a success

#155

Post by yodon »

jchallis wrote: post #61
themodelplumber wrote: post #19

Earlier quoted context omitted.

Fascinating. Q for you since you are so clued in. I am a ham radio operator and was thinking about novel forms of signal propagation. I landed on the idea of gravitons. Could gravitonic signal propagation be done somehow? While researching, I keep coming across familiar terms I know from radio land. Just curious if the fields here could be harnessed for communication. Thanks.

The big big downside of gravity waves is that they have no dipole radiators - with electric charge you have + and - and that allows very efficient propagation. For gravity there is only one charge ,and this allows only quadrupole radiation - making it extremely awful for transmission.

Yes, but there is no dispersion relation or absorption by the interstellar medium (not directly related to the quadrupole nature, but that which makes a radiation hard to detect also makes it hard to interfere with).

Re: Royal Navy says quantum navigation test a success

#156

Post by bumby »

elbigbad wrote: post #144
1nf_ wrote: post #79

Earlier quoted context omitted.

The majority of INS platform drift is from a thing called "tilt error" - where the IRS initially misjudges the exact direction of the gravitational vector during alignment. All this will do is improve the accuracy of the accelerometers but will still have the drift caused in the INS itself. How will this make such a large improvement over what we have already?

Can you talk more about this source of error? When I google this, your post is the main thing that comes up for the term…

A long, long time ago I used to work as a technician in a shop that aligned INS for aircraft (although I didn't work on them myself). I think what the OP is referring to is that during the alignment process, the assumption is that the acceleration due to gravity is always perpendicular to the INS gimbal frame. So if there are any errors in the INS leveling during alignment, they can cause errors in the INS calibration. I assume this is what the OP means by "tilt error" (although this is the first time hearing of the term). These errors then get compounded during use. You can look up INS alignment processes for more information.

Re: Royal Navy says quantum navigation test a success

#157

Post by jubjubbird »

narenkeshav wrote: post #86
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…

Would it be possible to replicate that on mobile phones? Or a special device is required? 1. trying to figure out the feasibility?

The MEMS accelerometers in our phones are in theory sensitive to gravity changes, but they're not nearly sensitive enough. This group is trying to improve the MEMS sensing technology, but it's doubtful it will be as good as classical gravity meters (falling mass, or spring) or quantum (BEC) ones:

https://www.gla.ac.uk/research/beacons/nanoquantum/wee-gglas...

One important distinction is between measuring gravity (generally, acceleration in the vertical direction) and the gravity gradient. The latter is generally easier and more useful for navigation.

Re: Royal Navy says quantum navigation test a success

#158

Post by andromeduck »

martopix wrote: post #148
white_dragon88 wrote: post #146

Earlier quoted context omitted.

I would imagine that there is is an insane amount of gravitational noise from things like the planet’s asymmetry and events occurring all the way from the core to the crust, the ocean… to cut through that noise you need one big thumper.

The most obvious source of noise seems to me the fact that the submarine is moving and has therefore nonzero accelerations all the time

Most obvious would be the phase of the moon.

Re: Royal Navy says quantum navigation test a success

#159

Post by yodon »

bottom999mottob wrote: post #33
HyperSane wrote: post #28

Earlier quoted context omitted.

There is no way that subs can be controlled accurately enough to do that.

There is no way anyone would hyperbolize the experience of their friend squeezing a submarine through ravines on the internet.

When a storyteller has clearly hyperbolized the parts of their story that can be fact checked, they have destroyed any reason to believe the remainder of their words.

Re: Royal Navy says quantum navigation test a success

#160

Post by andromeduck »

smilespray wrote: post #53
andromeduck wrote: post #20

Earlier quoted context omitted.

Yup and it's called is called Terrain Contour Matching! https://en.wikipedia.org/wiki/TERCOM

Isn't this the old radar terrain mapping system codnamed FINGERPRINT? It's conceptually similar, but they didn't use quantum gravity mapping in the 50s.

Think so? I don't find anything on Google. I thinkOme documentary said it was called SLAM on the tomahawk?
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