back to article Did the Earth move for you, too? Grav waves sensed from black holes' bang 1.8bn LYs away

Scientists have recorded the most accurate reading of gravitational waves yet by using the upgraded LIGO and Virgo observatories together for the first time. The ripples were detected on August 14 at the Laser Interferometer Gravitational-wave Observatories (LIGO) in Louisiana and Washington state in the US, and the Virgo …

Anonymous Coward

VIRGO funding

... US National Science Foundation, which funds both detectors ...

To be clear, the US NSF funds both LIGO detectors (there are two). The VIRGO detector is funded primarily by CNRS and INFN - the French and Italian national organisations, with important contributions made by many laboratories across Europe.

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Mass moves in mysterious ways

Science for the win!

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Re: Mass moves in mysterious ways

Actually it moves according to the Einstein equation.

"Mass tells spacetime how to curve"

"Curved spacetime tells mass how to move".

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Re: Mass moves in mysterious ways

...and the Heart of Gold tells them both to get knotted, IIRC.

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Anonymous Coward

60 square degrees

is still a hell of a lot of sky to scan for something, particularly when you don't know what to expect.

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Coat

Re: 60 square degrees

"... is still a hell of a lot of sky to scan for something ..."

Given that there are about 41253 square degrees in a sphere then reducing the search area to just 60 is not bad though.

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Boffin

A three-sun tidal wave!

That's a lot of gravity!

I wonder how near you'd have to be to personally experience the tug.

But gravitational energy is negative and exactly balances the positive mass which creates it. How can positive mass be converted into negative energy as the article suggests?

It makes more sense if three suns' worth of mass were lost as radiation, as that would cause a three-sun ripple or wave in its gravitational field. A black hole itself cannot release mass that fast, so it would have been outlying stuff that hadn't quite fallen in yet.

Or, is my physics farcically bad?

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Re: A three-sun tidal wave!

I think defining what "gravitational energy" is supposed to be would be a good starting point.

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Re: A three-sun tidal wave!

The tidal forces (difference between your head and feet) will always swamp the wave effect so you will be spaghettified well before you could feel the waves.

There's a more mathematical answer elsewhere on this site in the comment related to a previous detection by Ken Strain who actually works in this area.

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Re: A three-sun tidal wave!

I wonder how near you'd have to be to personally experience the tug.

When the detection as announced last year I worked out what the displacement would be from a light year away. I forget the exact result now, but I think it was on the order of a metre. The problem is, how would you experience that? It's a contraction and expansion of space and time, propagating at the speed of light. Would you even be able to detect that with your human senses? Would the tidal force instantaneously tear apart all matter larger than an atom? I'm having trouble thinking that one through.

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Re: A three-sun tidal wave!

I am inclined to think you are right. Energy in the gravitational wave being absorbed by any solid or liquid mass. Fascinating.

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Facepalm

Re: A three-sun tidal wave!

You need gravitational energy defining?

It is minus the work that is done in moving an object in a gravitational field from one place to another. The absolute gravitational potential energy of an object is minus the work needed to move it to a point indefinitely far away from the centre of the field.

I learned that at school, I suppose you need a degree in astrophysics to be taught that these days.

And no, I am not going to post Einstein's equations for the associated curvature of spacetime, which the philosophically-minded may take as a more ontological definition.

Sigh.

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Re: A three-sun tidal wave!

Human senses tend to rely on rate of change: a small but sharp change in spacetime would feel much the same scale as a large but leisurely one. Gravitational mass is assumed to be identical to inertial mass, so a change in gravity would be indistinguishable from an acceleration due to change in velocity. But if the wave took say half an hour to peak, then it would have to be stonkingly huge, three suns' worth maybe, before one would feel it.

Interestingly, large black holes have gentler tidal forces than small ones, while the effects of a merger are more dramatic. So one stands a better chance of feeling the wave from a couple of supermassives merging than one does from a couple of babies like the two observed this time round. Yes, the tides would dominate with these two.

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Re: A three-sun tidal wave!

"I think defining what "gravitational energy" is supposed to be would be a good starting point."

It's a heavy subject, man...

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Re: A three-sun tidal wave!

*I* once personally experienced a tug, you know. Oh yes.

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Re: A three-sun tidal wave!

Um. I'll share the little secret Ms McEvoylet us into in fourth year GCE physics.

Everything you are taught at O level is a lie. When you do A level, the first thing yhou need to do is forget everything you've been taught.

The the same thing happens at degree level.

Or so she said. She's not around to check with, alas.

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Units of Energy

Does anyone know the Reg unit for the "Energy equivalent to three solar masses" ? - Like 3 ChuckNorrises ?

Or is that a contradiction in terms, because there can only be one Chuck Norris.

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Anonymous Coward

Re: Units of Energy

3 *Black* Chuck Norrises.

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Re: Units of Energy

Crossover upvote for you!

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For anyone interested in reading the paper...

https://arxiv.org/abs/1709.09660

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Coat

and the Virgo detector near Pisa, Italy.

Are we sure it wasn't caused by the collision of 2 pizza dough's being spun and colliding?

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If you like such racist comments, aren't you sure those in the US was not due to people firing at each other there? After all, lead has a bigger mass than pizza. Or maybe two obese Americans nearby the detector?

BTW: while pizza today is made everywhere, it came from Naples, not Pisa. Typical food in Tuscany is different.

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So now it's racist to suggest people in Italy make pizza?

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LDS
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It shows you know very little beyond stereotypes. A joke about the Tower of Pisa at least would have shown a little knowledge.

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When I'm asked to visualize Italy, I would probably imagine a series of images gleaned from experience, among them a pizza. Many people like to engage in word play involving such shared images, to the delight of all.

Well, not all. There's you. You don't appear to be having any fun. It's too bad too, because a good chuckle now and then can really brighten up this dreary old world. :)

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It wasn't funny. Again, you just show your little knowledge of the world. As if visualizing America I would see hamburgers or cowboys hats only, or visualizing England fish and chips. You also decided to mock only the Italian detector, as if, of course, Italians can't do nothing more than pizza. Just, Pisa is one of the cradles of modern physics. A couple of names like Galileo and Fermi should tell you something....

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Stop this SJW bullshit of being offended on the part of others for no go good reason forthwith!

It wasn't funny.

I'm part italian and I don't care.

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3 suns just vanished?

where did the other 3 solar masses go?

31 + 25 = 56 and not the stated 53.

That's an awesome amount of matter just disappearing!

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Re: 3 suns just vanished?

That's the energy in the gravitational waves.

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Re: 3 suns just vanished?

thanks John. I re-read and now understand... but shiiiiiiiit. Thats a hell of a bang!

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Re: 3 suns just vanished?

How is matter converted into gravitational energy?

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Re: 3 suns just vanished?

E=mc^2

Okay, that's the relationship, not the method and in the context of this event I have no real idea.

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Re: 3 suns just vanished?

I think the energy came from the angular momentum of that system, which in this case was pretty huge. The waves carry the angular momentum away, allowing the holes to spiral into each other.

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m(ass)es

53 solar masses? Isn't that a bit small for a black hole?

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Re: m(ass)es

Yes, infinitely small.

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tfb
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Boffin

Re: m(ass)es

No, a 53 solar mass BH is fairly massive for a BH which originated from a collapsed star rather than by some long accretion process. In fact I am fairly sure that it's above what the upper limit was expected to be until recently: I think all of the things LIGO has observed so far (certainly the first observation) were rather unexpectedly heavy objects.

(Obviously the 53 solar mass object *didn't* originate from a collapsed star directly but from a merger, but even the two ancestors are rather heavy for stellar BHs I think).

(as to size: they're pretty small: I think the Schwarzschild radius of the resulting object is 156km -- or 7097 brontosaurus (linguine is kind of an impractically small unit here)).

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Re: m(ass)es

AIR from the discussions regarding the first observation, 30 solar masses is about the limit for "primordial" black holes. These were formed directly from hydrogen clouds, and have not had any substantial mass gains since.

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I'm glad to see they haven't been wasting taxpayers' money on anything so mundane as curing diseases. That would never do.

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You know where to send your proposal to get money for your genius idea of "curing diseases", buster!

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Mushroom

Indeed not: they're spending taxpayers' money on doing some deeply astonishing engineering. Engineering, sadly has never benefited humanity in any way at all: cars and NMR machines are harvested by artisanal labourers wearing clothes of hand-spun wool.

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Facepalm

And every time we cure a disease, someone invents a new one! >:-(

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Incomprehensible

Right, i've had enough.

A light year i can deal with.

A galaxy 100 light years across i can cope with.

But 1.8bn light years away is the final straw.

I bet it's not even near the edge either.

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Re: Incomprehensible

It's about 13% of the way to the edge.

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Holmes

Re: Incomprehensible

A galaxy isn't 100 light years, more like 100,000 light years.

That's your difficulty, missed a step. Now that 1.8bn light years doesn't look so big!

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Alien

Incredible stuff, as the Nazz says.

My take, FWIW, where did it all come from? Big bang is too easy a term to describe the entities involved in this discovery.

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G F Fielding

I am very excited about these new developments and I will watch with a keen interest.

(G F FIELDING).

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