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Physicists detect signs of neutrinos at Large Hadron Collider

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Re: Physicists detect signs of neutrinos at Large Hadron Collider

#111

Post by db48x »

zodiac wrote: post #108
hungryforcodes wrote: post #102

Earlier quoted context omitted.

But it's at pretty near the speed of light and how would there be an advantage to doing it the way the GP says?

Let the radius of the earth be R. Say you want to send a message from the north pole to the south pole. If you use radio waves that travel around the earth, the shortest distance they can travel is πR ≈ 20,000km. If you use neutrinos that travel through the earth, the shortest distance is 2R ≈ 12,700km. So the advantage is about 7,300km (or in time units, 25ms ≈ 7,300km / (the speed of light))

You’re talking about using gigawatts of power, and detectors that weigh in at thousands of tons, in order to send a signal best measured in bits per decade. It’s an idiotic suggestion; fiber optics beat anything based on neutrinos hands–down. Authors who make their aliens use neutrino communications are idiots. But that’s ok, most authors are idiots, and most of them stopped taking physics in high school. Authors who take physics seriously are quite rare, even in the science fiction genre.

If you want a book written by someone who knows some real physics, read The Clockwork Rocket by Greg Egan. He changed one simple law of physics, worked out the consequences for quantum mechanics and relativity, made up some plausible–enough biology, and wrote a series of books in the resulting universe. The characters in the book have to discover or teach each other those laws, so the book is actually a pretty decent way to learn something of the laws of our own universe too. He wrote a huge amount of supplementary material as well, going into all the details. Truly an astounding accomplishment.

Re: Physicists detect signs of neutrinos at Large Hadron Collider

#112

Post by hungryforcodes »

db48x wrote: post #111
zodiac wrote: post #108

Earlier quoted context omitted.

Let the radius of the earth be R. Say you want to send a message from the north pole to the south pole. If you use radio waves that travel around the earth, the shortest distance they can travel is πR ≈ 20,000km. If you use neutrinos that travel through the earth, the shortest distance is 2R ≈ 12,700km. So the advantage is about 7,300km (or in time units, 25ms ≈ 7,300km / (the speed of light))

You’re talking about using gigawatts of power, and detectors that weigh in at thousands of tons, in order to send a signal best measured in bits per decade. It’s an idiotic suggestion; fiber optics beat anything based on neutrinos hands–down. Authors who make their aliens use neutrino communications are idiots. But that’s ok, most authors are idiots, and most of them stopped taking physics in high school. Authors who…

Awesome-- I've heard of him, but didn't know he had done so much detailed work on his stories. I'll check him out.

Re: Physicists detect signs of neutrinos at Large Hadron Collider

#113

Post by JProthero »

gus_massa wrote: post #45
JProthero wrote: post #39

Earlier quoted context omitted.

This is a great analogy, I'd never seen it translated into tangible terms like that before. I remember reading that, at close enough range, the neutrino emissions from a supernova would be intense enough to be dangerous to structures made of ordinary matter, despite the weakness of their interactions, and that they would reach an observer earlier than other forms of radiation due to their ability to escape the collap…

Perhaps " Lethal Neutrinos " https://what-if.xkcd.com/73/

I think my source was a book, but the XKCD is a better link! I think the book reference I had mind may have stated the effect in terms of force.

Re: Physicists detect signs of neutrinos at Large Hadron Collider

#114

Post by ithkuil »

hungryforcodes wrote: post #110
zodiac wrote: post #108

Earlier quoted context omitted.

Let the radius of the earth be R. Say you want to send a message from the north pole to the south pole. If you use radio waves that travel around the earth, the shortest distance they can travel is πR ≈ 20,000km. If you use neutrinos that travel through the earth, the shortest distance is 2R ≈ 12,700km. So the advantage is about 7,300km (or in time units, 25ms ≈ 7,300km / (the speed of light))

Fair enough, your calculation seems valid. But my point still stands -- are we going to build enormous LHCs all over the world to get a (maximum) 24 millisecond advantage in global communications via neutrinos?!

I assume the story is "if we find a magic new tech that is otherwise similar to our existing tech in terms of cost effectiveness, size, bandwidth, reliability, etc, and it also could pass straight through earth, then we could shave off 25ms and that would be useful"

Re: Physicists detect signs of neutrinos at Large Hadron Collider

#115

Post by Ma8ee »

astrange wrote: post #109
Ma8ee wrote: post #95

Earlier quoted context omitted.

No, they are still not the same. If I understand you correctly, you are saying that Dark Matter would correspond to Gravitons. But that would just prove my point, because Gravitons is just a hypothetical explanation of gravity, in the same way as Dark matter is a hypothetical explanation of, e.g., the rotation profiles of galaxies. (And here we have so far left out that the only reason Dark matter makes sense is beca…

Well, one reason dark matter is winning over modified gravity theories is that there seem to be some galaxies that don't have dark matter. So MOND needs more special pleading there, unless the observations are wrong.

The only thing I was arguing was that Gravity has a much more solid basis than Dark Matter. I certainly don't think I made it sound like I think MOND is more likely than Dark Matter (even though I confess that I still think the issue is far from settled).

Re: Physicists detect signs of neutrinos at Large Hadron Collider

#116

Post by zodiac »

hungryforcodes wrote: post #110
zodiac wrote: post #108

Earlier quoted context omitted.

Let the radius of the earth be R. Say you want to send a message from the north pole to the south pole. If you use radio waves that travel around the earth, the shortest distance they can travel is πR ≈ 20,000km. If you use neutrinos that travel through the earth, the shortest distance is 2R ≈ 12,700km. So the advantage is about 7,300km (or in time units, 25ms ≈ 7,300km / (the speed of light))

Fair enough, your calculation seems valid. But my point still stands -- are we going to build enormous LHCs all over the world to get a (maximum) 24 millisecond advantage in global communications via neutrinos?!

> If there were a way to reliably detect neutrinos in sufficient quantities they'd be ideal since you could send messages through the earth and at near light speed, I suppose.

> As opposed to how we communicate now globally?

From this interaction I thought you'd missed the point that "send messages through the earth" is something we're currently not doing. Of course you're right that the "if there were a way to reliably detect neutrinos" is doing a lot of work.

Re: Physicists detect signs of neutrinos at Large Hadron Collider

#117

Post by zodiac »

db48x wrote: post #111
zodiac wrote: post #108

Earlier quoted context omitted.

Let the radius of the earth be R. Say you want to send a message from the north pole to the south pole. If you use radio waves that travel around the earth, the shortest distance they can travel is πR ≈ 20,000km. If you use neutrinos that travel through the earth, the shortest distance is 2R ≈ 12,700km. So the advantage is about 7,300km (or in time units, 25ms ≈ 7,300km / (the speed of light))

You’re talking about using gigawatts of power, and detectors that weigh in at thousands of tons, in order to send a signal best measured in bits per decade. It’s an idiotic suggestion; fiber optics beat anything based on neutrinos hands–down. Authors who make their aliens use neutrino communications are idiots. But that’s ok, most authors are idiots, and most of them stopped taking physics in high school. Authors who…

I am well aware of the "disadvantages" (to put it mildly) of hypothetical neutrino-based communications and I never suggested that they could viably replace EM-based communication
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