ET Will Phone Home Using Neutrinos, Not Photons 299
KentuckyFC writes "Neutrinos are better than photons for communicating across the galaxy. That's the conclusion of a group of US astronomers who say that the galaxy is filled with photons that make communications channels noisy whereas neutrino comms would be relatively noise free. Photons are also easily scattered and the centre of the galaxy blocks them entirely. That means any civilisation advanced enough to have started to colonise the galaxy would have to rely on neutrino communications. And the astronomers reckon that the next generation of neutrino detectors should be sensitive enough to pick up ET's chatter."
Re:OK I got dibs (Score:3, Interesting)
Encryption? (Score:2, Interesting)
Too little too late? (Score:1, Interesting)
Unless aliens have some sort of incredible way of communicating through subspace, or wormholes, or some other fantastic medium through which they can shorten or eliminate the pesky problem of distance, neutrinos over photons won't make too much of a difference, even if they are used solely for advertising their presence.
Re:Civil rights of aliens (Score:5, Interesting)
Re:Still bound by the speed of light (Score:1, Interesting)
Re:Speed of Light != Useless (Score:5, Interesting)
They had it down to 18 hrs from Great Britan... I think that's damned impressive.
Re:Still bound by the speed of light (Score:5, Interesting)
Not if they're made of meat [baetzler.de].
Re:What about those from the sun? (Score:3, Interesting)
I watched my husband help design and build a detector for his PhD research. There are a lot of scientists hard at work on the problem, but right now advances are incremental.
Re:Noise free? (Score:1, Interesting)
The beaming means you don't need quite as much signal, because it doesn't point in all directions. The energy of these neutrinos is also much larger than those produced in stellar reactions, so they are easy to discriminate.
The problem, of course, is that detecting them efficiently is well-nigh impossible. This is what I do, and it's hard -- your data rate would be abysmal. I think radio or lasers is really a much better choice.
Re:What about those from the sun? (Score:3, Interesting)
No. (Score:1, Interesting)
The SNO experiment used 1000 tonnes of heavy water in a 12m acrylic sphere suspended in a 30-meter barrel shaped cavity 6800 feet below ground, and was only able to detect several dozen of the trillions of neutrinos passing through the area.
What will your receiver look like, if you want a usable signal? Or your transmitter for that matter?
Re:OK I got dibs (Score:2, Interesting)
Re:Still bound by the speed of light (Score:5, Interesting)
Think of your own life. When you are 10 the idea of working on one project for a year seems like forever. Heck you can not even stand ten minutes of down time. It seems sooo long to you.
By the time your 40 a year seems like a short amount of time and five minutes is a blink of an eye.
If you where a 1000 years old and where going to live for another 50,000 years waiting 200 years for a reply wouldn't seem so bad.
Even waiting a thousand years for data to come back from a probe is very doable.
But no I do not think you can have ultra turtles.
Re:Still bound by the speed of light (Score:4, Interesting)
Apparently, it does. Entangled particles *always* have opposite angular momentum. This has been observed experimentally. It may not be accurate to say that one particle is "transmitting" to another. It may be more accurate to say that each particle is independently reading the same variable in some higher dimension. But something is happening. It's not a trick.
Whether or not we can use this information to transmit information of our choosing is another issue entirely.
doing so breaks the link
It's possible that what you mean to say is that observing the system causes it to collapse, in which case you are right. But I'm not aware of any way to actually break the link between two entangled particles.
Re:Still bound by the speed of light (Score:3, Interesting)
You're oversimplifying it a bit. There really is something spooky going on there. The full explanation is lengthy, but I'm going to give it a try anyway.
First off, consider the photon from a classical physics perspective. We know photons can be polarized to discreet angles, and we know how to compute the chances of a photon passing through a polarizer as a function of the difference in angles between the photon and the polarizer. Say you send a beam of incoherent light through a polarizer oriented at an arbitrarily selected 12.34 degrees. 50% of that light will pass through and the other 50% will be absorbed or deflected. But that 50% that passes through will now be oriented at 12.34 degrees. 100% of that beam of light will pass through through one or more polarizers oriented at 12.34 degrees, with no absorption.
If you pass your beam of 12.34-degree light through a polarizer oriented at 57.34 degrees, you'll find that 50% of that light will be absorbed and the other 50% will pass through, and the 50% that passes through will now be oriented at 57.34.
If you pass your beam of 12.34-degree light through a polarizer oriented at 102.34 degrees, you'll find that all of that light will be absorbed.
But, if pass some 12.34-degree light through a 57.34-degree polarizer, and then pass what makes it past that first filter through a 102.34-degree polarizer, you find that 25% of the original beam of 12.34-degree light makes it through. In other words, the light can't be twisted 90 degrees in one step, but it can be done in two steps.
As it happens, the chance of a photon passing through a polarizer is the square of the cosine of the difference in angle between the photon and the polarizer. For easy remembering, it's 100% at the same angle, 75% at 30 degrees, 50% at 45 degrees, 25% at 60 degrees, and 0% at 90 degrees.
Now, let's go quantum. In the quantum world, "measuring" the polarization angle of an individual photon has different meaning. If the photon is randomly polarized, you have no way to pin its angle down to a particular value. The best you can do is pass the photon through a polarizer. This will either pass the photon through, aligning the photon's angle to match, or deflect the photon. All that you are allowed to say about the previous polarization angle of a photon that passes through the detector is "well, it wasn't 90 degrees apart from my detector, otherwise it wouldn't have passed through.".
Now, with entanglement, things become really strange, though. Based on a classical physics view, usinglaws of conservation of this and that you could deduce that a pair of photons created from one subatomic event would have zero net momentum and the same random angle of polarization. You would then go on to predict that if you measured both members of each pair with polarizers set at the same angle, there would be no correlation of results, because each photon would be its own entity with its own 50% chance to pass the deflector or be absorbed by it, each not influenced by the other.
But quantum mechanics predicts (and I'm actually not 100% clear on why or how) that with entangled photons, the rate of correlation of measurement of their polarization angles is the square of the cosine of the difference in angles between the two detectors. And these predictions are known to be true. There's even a name for them: Violations of Bell's Inequality.
So, the implications should be pretty clear. If both detectors are at the same angle, their results will correlate 100% of the time. So if Detector A registers a "pass" with one member of an entangled photon pair, Detector B either will have already registered the same result or will eventually register the same result. Note that this applies if you change the orientation of