1642: "Gravitational Waves"

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Zinho
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1642: "Gravitational Waves"

Postby Zinho » Thu Feb 11, 2016 6:37 pm UTC

Image

"That last LinkedIn request set a new record for the most energetic physical event ever observed. Maybe we should respond." "Nah."

I read somewhere that if users aren't trading cat pictures on your system, the system is broken...

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Re: 1642: "Gravitational Waves"

Postby Flumble » Thu Feb 11, 2016 8:11 pm UTC

EVENT: xkcd UPDATE ON THURSDAY EVENING!
EVENT: ZORLAX THE MIGHTY AND 41 OTHERS LIKE THIS xkcd

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Re: 1642: "Gravitational Waves"

Postby J%r » Thu Feb 11, 2016 8:55 pm UTC

Zinho wrote:I read somewhere that if users aren't trading cat pictures on your system, the system is broken...

Perhaps that's what linkedin is for. It's actually 'Link kedi', kedi is Turkish for cat.

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david.windsor
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Re: 1642: "Gravitational Waves"

Postby david.windsor » Thu Feb 11, 2016 9:50 pm UTC

Wait... nobody is using it to send porn?
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Re: 1642: "Gravitational Waves"

Postby Keyman » Thu Feb 11, 2016 11:16 pm UTC

david.windsor wrote:Wait... nobody is using it to send porn?

No? Gravitational waves were detected when two huge bodies slammed together.
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Re: 1642: "Gravitational Waves"

Postby rmsgrey » Fri Feb 12, 2016 1:53 am UTC

Keyman wrote:
david.windsor wrote:Wait... nobody is using it to send porn?

No? Gravitational waves were detected when two huge bodies slammed together.

Though most porn doesn't end with a new body appearing...

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Re: 1642: "Gravitational Waves"

Postby Pfhorrest » Fri Feb 12, 2016 2:21 am UTC

rmsgrey wrote:
Keyman wrote:
david.windsor wrote:Wait... nobody is using it to send porn?

No? Gravitational waves were detected when two huge bodies slammed together.

Though most porn doesn't end with a new body appearing...

No, that's a topic for particle physics instead.
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Re: 1642: "Gravitational Waves"

Postby rhomboidal » Fri Feb 12, 2016 5:28 am UTC

The mortgage offer from the Triangulum Galaxy sounds like a tetrahedron scheme.

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Re: 1642: "Gravitational Waves"

Postby StClair » Fri Feb 12, 2016 5:31 am UTC

the ... music of the spheres.

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Re: 1642: "Gravitational Waves"

Postby Eutychus » Fri Feb 12, 2016 6:17 am UTC

Am I the only one who immediately wanted to send Randall a LinkedIn request?
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Re: 1642: "Gravitational Waves"

Postby The Moomin » Fri Feb 12, 2016 9:07 am UTC

Maybe the gravity waves are a LinkedIn request in morse code from Matthew McConaughey.
I possibly don't pay enough attention to what's going on.
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Re: 1642: "Gravitational Waves"

Postby DonJaime » Fri Feb 12, 2016 9:22 am UTC

I don't think 'pedant' is really the right word.

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Re: 1642: "Gravitational Waves"

Postby Eternal Density » Fri Feb 12, 2016 9:29 am UTC

Here's the relevant press release from LIGO, for convenience/posterity: https://www.ligo.caltech.edu/news/ligo20160211

rmsgrey wrote:
Keyman wrote:
david.windsor wrote:Wait... nobody is using it to send porn?

No? Gravitational waves were detected when two huge bodies slammed together.

Though most porn doesn't end with a new body appearing...

That depends on the ratio of condoms to hotdogs.
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Re: 1642: "Gravitational Waves"

Postby cellocgw » Fri Feb 12, 2016 12:46 pm UTC

rhomboidal wrote:The mortgage offer from the Triangulum Galaxy sounds like a tetrahedron scheme.


What else would we expect from someone with your username? :roll:

I award you today's Free Internet anyway.
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Re: 1642: "Gravitational Waves"

Postby Reecer6 » Fri Feb 12, 2016 1:28 pm UTC

This Xyhnoperian prince just sent me a wave saying he needed a small amount of a thousand dollars to take his space bucks out of his galactic royal treasury, and that he'll gladly share the trillions with me if I do, but I just can't figure out how to slam my money together hard enough so he'll get it. Any tips?

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Re: 1642: "Gravitational Waves"

Postby Mahnarch » Fri Feb 12, 2016 4:23 pm UTC

I have a money smoosher.

If you send it to me, I'll make sure it gets to him.

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JohnTheWysard
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Re: 1642: "Gravitational Waves"

Postby JohnTheWysard » Fri Feb 12, 2016 5:11 pm UTC

The next generation of gravity wave detectors will examine much longer wavelengths; eventually they hope to detect the waves from the Big Bang.

Just hope it's a voice saying "Let there be Light" in Hebrew, and not Brahma saying "OK, Vishnu, you can play with this for a while but then give it to your brother Shiva!"

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Re: 1642: "Gravitational Waves"

Postby david.windsor » Fri Feb 12, 2016 6:00 pm UTC

JohnTheWysard wrote:The next generation of gravity wave detectors will examine much longer wavelengths; eventually they hope to detect the waves from the Big Bang.

Just hope it's a voice saying "Let there be Light" in Hebrew, and not Brahma saying "OK, Vishnu, you can play with this for a while but then give it to your brother Shiva!"

It will be a bowl of petunias saying "Not again."
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Re: 1642: "Gravitational Waves"

Postby Barker » Fri Feb 12, 2016 6:14 pm UTC

EVENT:Try this one weird trick to detect gravity waves!

Cervisiae Amatorem
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Re: 1642: "Gravitational Waves"

Postby Cervisiae Amatorem » Fri Feb 12, 2016 6:35 pm UTC

Is it possible to purposefully encode information in gravitational waves and really send messages like this?

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Re: 1642: "Gravitational Waves"

Postby peewee_RotA » Fri Feb 12, 2016 6:39 pm UTC

We suddenly stopped getting messages when Google Wave shut down
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Re: 1642: "Gravitational Waves"

Postby Pfhorrest » Fri Feb 12, 2016 7:00 pm UTC

Cervisiae Amatorem wrote:Is it possible to purposefully encode information in gravitational waves and really send messages like this?

If you have amazing control of some enormous masses and the ability to move them at high velocities and change those velocities rapidly, then yes.

Or, alternately, if your recipient has much more sensitive equipment than we do, then the same as above but with smaller masses and lower velocities.

Technically when you tap out an old-fashioned telegram, the motion of your hand is encoding the same telegram message into gravitational waves broadcast across the universe at an amplitude that pretty much nobody will ever notice.
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cryptoengineer
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Re: 1642: "Gravitational Waves"

Postby cryptoengineer » Fri Feb 12, 2016 7:12 pm UTC

Two interesting points:

First:
The waves detected are two black holes spiraling into each other.

The period of the rotation shortens as they get closer, so the frequency of the waves gets higher, but they remains within human hearing range.
You can listen to the coalescence here:

https://youtu.be/aEPIwEJmZyE?t=2731 (that's 45:30 into the press conference).

Second: (from an acquaintence in another forum)

Some kind soul on one of the car forums I lurk on has posted a link to
the paper...

https://dcc.ligo.org/public/0122/P15091 ... 150914.pdf

Page 3 has a -scary acceleration curve for the final approach.

From a relative velocity of about 0.32c to 0.6 c in about 0.2 of a
second, or about 1.4c/second, for a body with mass of order 30 solar
masses!

And unsurprisingly, that's the average over that .2 of a second - the
curve itself is a hockey stick, with a -much- higher acceleration just
before impact :-O

Science, don't you just love it?

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Re: 1642: "Gravitational Waves"

Postby eidako » Sat Feb 13, 2016 12:33 pm UTC

DonJaime wrote:This reminds me of http://everything2.com/user/sam512/writeups/On+Digital+Extremities, for obvious reasons.


Amusing story, though it makes one wonder what a so-advanced-it's-magic race would consider payment to be. Chances are it would be something absolutely worthless to us (dilithium crystals) or something beyond priceless (the souls of countless teenage girls spanning the course of human history). When godlike beings can warp reality, create complex objects out of thin air, and in general seem to be above concepts like scarcity, the thought that they would want anything from an inferior civilization like us is a scary prospect.

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Re: 1642: "Gravitational Waves"

Postby Neil_Boekend » Sat Feb 13, 2016 12:38 pm UTC

I still hope the first indication of alien life will not be all children on earth stopping in their tracks, chanting "We are coming".
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Re: 1642: "Gravitational Waves"

Postby rmsgrey » Sat Feb 13, 2016 3:24 pm UTC

eidako wrote:
DonJaime wrote:This reminds me of http://everything2.com/user/sam512/writeups/On+Digital+Extremities, for obvious reasons.


Amusing story, though it makes one wonder what a so-advanced-it's-magic race would consider payment to be. Chances are it would be something absolutely worthless to us (dilithium crystals) or something beyond priceless (the souls of countless teenage girls spanning the course of human history). When godlike beings can warp reality, create complex objects out of thin air, and in general seem to be above concepts like scarcity, the thought that they would want anything from an inferior civilization like us is a scary prospect.


Being post-scarcity in material goods doesn't preclude an appetite for art or other forms of data. Who knows - maybe Plan 9 will turn out to be a sleeper hit over in Andromeda?

Of course, if they get hooked on Reality TV, that could make things awkward for us - "In this decade's episode, an extinction-level asteroid is on a collision course with the planet. Let's see how the monkey-people react!"

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Re: 1642: "Gravitational Waves"

Postby ManaUser » Sat Feb 13, 2016 6:37 pm UTC

Cervisiae Amatorem wrote:Is it possible to purposefully encode information in gravitational waves and really send messages like this?

Sure, if you can push black holes around. No problem for Zolax, apparently. They don't call Zolax "The Mighty" for nothing.

Of course technically human-scale events like jumping or waving your hand should create gravitational waves too, but needless to say they would be substantially weaker and harder to detect.

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Re: 1642: "Gravitational Waves"

Postby da Doctah » Sun Feb 14, 2016 1:38 am UTC

rmsgrey wrote:Being post-scarcity in material goods doesn't preclude an appetite for art or other forms of data.


Oh me yarm, they've come for our Bitcoins!

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Re: 1642: "Gravitational Waves"

Postby Eternal Density » Sun Feb 14, 2016 1:47 am UTC

Reecer6 wrote:This Xyhnoperian prince just sent me a wave saying he needed a small amount of a thousand dollars to take his space bucks out of his galactic royal treasury, and that he'll gladly share the trillions with me if I do, but I just can't figure out how to slam my money together hard enough so he'll get it. Any tips?
Try Dogecoin. That'll at least get you to the moon.
peewee_RotA wrote:We suddenly stopped getting messages when Google Wave shut down
Ah, I'd been looking to make a Google Wave joke but I couldn't make it work.
Thanks.
da Doctah wrote:
rmsgrey wrote:Being post-scarcity in material goods doesn't preclude an appetite for art or other forms of data.


Oh me yarm, they've come for our Bitcoins!

Haha, I hadn't seen that when I thought of Dogecoin :P

Or try Earth Coin https://www.youtube.com/watch?v=P-lVEv0TaQs
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Re: 1642: "Gravitational Waves"

Postby Soupspoon » Sun Feb 14, 2016 3:11 am UTC

rmsgrey wrote:Being post-scarcity in material goods doesn't preclude an appetite for art or other forms of data.

I'm minded of this story. (Which doesn't seem to get a better treatment, anywhere else I've looked, but if you know the story from the summary, you'll know what I mean.)

ETA: Or perhaps read it here? I haven't checked beyond the first page, but it might be complete. Anyway, just to demonstrate what I was thinking of when I read the above....

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Re: 1642: "Gravitational Waves"

Postby orthogon » Sun Feb 14, 2016 9:36 am UTC

ManaUser wrote:
Of course technically human-scale events like jumping or waving your hand should create gravitational waves too, but needless to say they would be substantially weaker and harder to detect.

I find it strange that the whole thing is being presented as though only very unusual situations cause gravitational waves. As I understand it most movements of mass cause the waves, but you need some really colossal masses and huge accelerations before they're strong enough to detect.
xtifr wrote:... and orthogon merely sounds undecided.

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Re: 1642: "Gravitational Waves"

Postby Soupspoon » Sun Feb 14, 2016 12:04 pm UTC

orthogon wrote:
ManaUser wrote:
Of course technically human-scale events like jumping or waving your hand should create gravitational waves too, but needless to say they would be substantially weaker and harder to detect.

I find it strange that the whole thing is being presented as though only very unusual situations cause gravitational waves. As I understand it most movements of mass cause the waves, but you need some really colossal masses and huge accelerations before they're strong enough to detect.

<whisper whisper whisper>
..sorry, had the volume turned too low. What I was saying was that it takes unusual situations to create detectable gravity waves, at least at our current state of play. If it was even harder, we wouldn't1 yet have discovered them, and if it was much easier then we might or might not already have experienced anomalies that could even have been almost 'normal' life, like tides.

One of the benefits to the detection (other than adding to the evidence that Einstein had a lot of the right ideas, as well as the few ideas that he didn't) are not primarily "Hey, we can now detect colliding black holes, randomly throughout the universe!", although that may be a bonus, but more that perhaps we can now start to detect the ripples from beyond the opaque limits of the early Universe, beyond where we can examine through EM waves alone.

I mean, what sort of Gravity Events occurred right at the beginning..? Or, if that's still too tricky to disengage, in the bare moments afterwards when the precursor to the clumping started to happen?


1 Taking it as read that we did, this time, and it's not a highly-specific experimental error of some kind, naturally. ;)

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Re: 1642: "Gravitational Waves"

Postby rmsgrey » Sun Feb 14, 2016 1:06 pm UTC

orthogon wrote:
ManaUser wrote:
Of course technically human-scale events like jumping or waving your hand should create gravitational waves too, but needless to say they would be substantially weaker and harder to detect.

I find it strange that the whole thing is being presented as though only very unusual situations cause gravitational waves. As I understand it most movements of mass cause the waves, but you need some really colossal masses and huge accelerations before they're strong enough to detect.


All movements of mass create gravity waves, in much the same way that tossing a pebble into a lake creates waves - they're there, but they're hopelessly lost in the background. The analogy's not precise because water shows a distinction between surface waves (ripples) and body waves, but you get the idea.

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Re: 1642: "Gravitational Waves"

Postby orthogon » Sun Feb 14, 2016 4:20 pm UTC

To be clear, I wasn't referring to the discussion on this forum, but to the presentation in the media and to some extent in popular science programmes. I intended my post to be supportive of ManaUser and others.

Incidentally, is this - the way that enormous masses need to move incredibly fast to create barely detectable g-waves, whereas a few electrons can generate EM waves that are easily receivable thousands of kilometres away - the same thing as the idea that we often hear that gravity is in some sense very much weaker than electromagnetism?
xtifr wrote:... and orthogon merely sounds undecided.

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Re: 1642: "Gravitational Waves"

Postby Heimhenge » Sun Feb 14, 2016 6:48 pm UTC

orthogon wrote:Incidentally, is this - the way that enormous masses need to move incredibly fast to create barely detectable g-waves, whereas a few electrons can generate EM waves that are easily receivable thousands of kilometres away - the same thing as the idea that we often hear that gravity is in some sense very much weaker than electromagnetism?


When you hear "electromagnetism is 39 orders of magnitude stronger than gravity" what they're usually comparing is the size of the two forces between, say, two protons at a certain distance or a proton and an electron. But that can be misleading as discussed here:

http://www.huffingtonpost.com/victor-stenger/myths-of-physics-2-gravit_b_5718233.html

So I'm not sure that's the reason why gravitation waves are so weak. It's not like we're comparing two test masses, or requiring one mass to react to another's movement. Maybe it has something to do with the permeability of free space being "easier" for photons than for gravitons?

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Re: 1642: "Gravitational Waves"

Postby ijuin » Sun Feb 14, 2016 8:44 pm UTC

The other thread on this in the Science forum on this board cited an estimate that around four solar masses worth of energy were released by this black hole collision. That is approximately 10^48 joules, or ten thousand FOEs (1 FOE = 10^Fifty-One Ergs). One FOE is approximately the energy output of the Sun over its entire past and (projected) future lifespan, or the energy output of a Type Ia supernova.

It is this fantastically high energy that makes it visible at a range of over a billion light years. An event such as a stellar-mass black hole falling into Sagittarius A (our galaxy's central black hole, 30k light years from us) could be nine orders of magnitude less energetic and result in the same signal strength received at Earth.

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Re: 1642: "Gravitational Waves"

Postby ManaUser » Mon Feb 15, 2016 3:12 am UTC

So how much energy would it take to create an event here on Earth—let's say one kilometer from the detector—with the same signal strength?

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Re: 1642: "Gravitational Waves"

Postby Copper Bezel » Mon Feb 15, 2016 3:49 am UTC

Inverse square law, right? 9.5e12 kilometers to the light year, distance this time was like a billion light years, so that's another 10^9. Square that, and your signal would be 10^44 times smaller.

But LIGO could only detect a specific range of frequencies, and any event that would generate frequencies this high would necessarily have to be a very energetic one. A much longer wavelength would be much harder to detect and much more difficult to filter out from background noise. I mean, the whole idea of the interferometer is that the arm of the detector has to measurably change length while the packet of light is in transit. The slower the oscillation, the longer the detector needed.
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Re: 1642: "Gravitational Waves"

Postby ijuin » Mon Feb 15, 2016 5:02 am UTC

Copper Bezel wrote:Inverse square law, right? 9.5e12 kilometers to the light year, distance this time was like a billion light years, so that's another 10^9. Square that, and your signal would be 10^44 times smaller.


So, tens of kilojoules at that range. A NATO-standard hand grenade exploding (or any typical motor vehicle crash) would be energetic enough strictly in terms of energy released, but I think that a source needs to be separated from the detector by several times the detector's own length to avoid "near field" effects.

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Re: 1642: "Gravitational Waves"

Postby Ae7flux » Mon Feb 15, 2016 12:03 pm UTC

I first heard the local group joke in astronomy class more years ago than I care to remember. It's been one of my favourites ever since.
There is an x such that x entirely fails to signify just in case x lacks a specific combination of rotary and reciprocating motion.


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