# LISA Pathfinder drops its gravity-wave-finding golden boxes

Its publicity thunder stolen by last week's announcement that the Laser Interferometry Gravitational-wave Observatory has seen the signal of the waves, the European Space Agency's LISA Pathfinder has passed what the agency calls a “major milestone”. The LISA – Laser Interferometer Space Antenna – Pathfinder is a proof-of- …

1. #### billionth-of-a-metre accuracy

Isn't that a nanometer ?

Nanometer accuracy a million clicks away ? In space ?

Count my mind boggled.

1. #### Re: billionth-of-a-metre accuracy

Can some kind soul convert this to standard el Reg units please?

1. #### @Ru'

Unless I made a mistake, a nanometer is apparently 0.00000000714 linguine.

2. #### Re: billionth-of-a-metre accuracy

It isn't (yet?) part of SER units, but if we take a gnat's whisker to be the smallest gap through which visible light can propogate, then a nanometre is several gnat's milli-whiskers.

2. #### Re: billionth-of-a-metre accuracy

Compared to the accuracy level of LIGO - 10^-18 meters or nine orders of magnitude better - I'm not sure if this will be more accurate if it is really "only" accurate to 10^-9 meters.

Yeah, million km arms beats LIGO's 4km (which is actually 600 km since it is reflected back and forth 75 times) but it doesn't seem like it is enough to overcome LIGO's massive sensitivity advantage. Unless the larger arms have a much bigger effect i.e. 10x longer arms = 1000x greater sensitivity since gravity waves are traveling through three dimensions. Anyone know how the math works out on this comparison?

1. #### Re: billionth-of-a-metre accuracy @ DougS

This is just the test setup.. The full setup will use an orbital triangle with arms of rather impressive length, with a verymuch higher resolution than anything we could possibly hope to build on earth.

Because.. well... earth isn't big enough for starters.

2. #### You missed one

"First, it was planned and built long before last year's LIGO data collection run that led to last week's announcement, and launched in December 2015; second, replication matters in science."

Third - Now that we can detect them, it's time to see what we can detect with them. We have just realised it's possible to "see" with a whole new window to the universe.

3. This post has been deleted by its author

4. #### Major omission in the article

LISA Pathfinder is designed to detect gravitational waves in a different frequency range to the ones detected by LIGO. See, for instance: https://en.wikipedia.org/wiki/Gravitational_wave#/media/File:The_Gravitational_wave_spectrum_Sources_and_Detectors.jpg .

1. #### Re: Major omission in the article

"LISA Pathfinder is designed to detect gravitational waves in a different frequency range to the ones detected by LIGO."

Beat me to it. Asking what the point of LISA is now we have LIGO is like asking what the point of building radio telescopes is when we can already see visible light, or what the point of sonar is when we have ears. Just because they happen to look at the same kind of waves doesn't mean they're trying to do exactly the same thing.

1. #### Re: Major omission in the article

In all of the interviews I listened to concerning the confirmation of gravity waves, the boffins invariably pointed out that this was the beginning of an entire new method for exploring the universe. One visible light telescope wasn't considered "enough" nor were the first telescopes designed to detect radio waves or x-rays. Too, one major advantage of gravity wave detectors is they can "see" farther back in time than electromagnetic radiation will allow. This is a really good start, but it is just a start.

5. #### Year: 2095

(in a nasal, echoey, crackley voice) - 'We apologize for the delay of the 07:50 time-warp tunneling service from East Cheam to the Large Magellanic Cloud this morning, this is due to the wrong frequency gravitational waves permeating the space-time continuum around Clapham and Tooting.'

6. #### GOLD....PLATINUM!!!!

At the very least, this will divert the attentions of thieves nicking copper cable of the rail/motorway systems.

This could start a whole new space race of Shell suited astronauts attempting to get into space in 1975 Transit vans with catapult launch systems. Expect the first attempts soon (As soon as they have nicked enough rubber bands for the launch system and visited Macburger for supplies).

7. #### The heavens are sacred and house of the mighty gods!

Stop littering them with science instruments like the tops of volcanoes!

8. #### Re. alien SPAM

"Enlarge your pseudopods with this One Weird Trick"

"Has your black hole been involved in a collision that wasn't your fault?"

"Send 5 cubic metres of Element 93 to this star system, and get 5000 by the next galactic rotation"

"Files locked? Pay us 50,000 credits and we will unlock them for you"

1. #### Re: Re. alien SPAM

Nice, but you're a week late:

http://xkcd.com/1642/

1. #### Re: Re. alien SPAM

CARRIER LOST

in space

9. #### Skaffen-Amtiskaw

All this talk of minute electrostatic forces and boxes following spaceships puts me in the mind of field effectors and knife-missiles.

RIP IMB.

10. I'm not saying it's not impressive but if they've launched the trial now, why do we have to wait 18 years to launch the rest if it works?!

1. Hopefully the grand LIGO success will cause a newly-formed Yank committee to rejoin eLISA and make it LISA again, with originally-designed full capability. And to accelerate that ridiculously far-future deadline to something much sooner. LISA will be even more awesome than LIGO.

11. #### Re. LISA

Maybe they can sell it as a way to locate foreign nuclear submarines? :-)

I had an intriguing idea about detecting a SCRAM on a reactor by listening out for a specific set of neutrino signatures but detecting mass displacement directly will also work.

The sticking point is that my modified detector uses materials not found in nature, but so far it has attracted some interest.

See paper soon to be published in "Scientific American".

12. #### Yes, replication matters

I was staggered to read in the detailed article published on arxiv (http://arxiv.org/ftp/arxiv/papers/1602/1602.03837.pdf) that the claim to have found gravitational waves is based on one observation. The run was conducted when the observation occurred happened when German and Japanese devices that also aim to find these waves were not operational.

I'm sure the researchers involved have done an excellent job of eliminating other possible explanations but, really, one observation?

1. #### Re: Yes, replication matters

They will have a lot of explaining to do if they fail to detect any more ...

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