from Hacker News

LIGO Detects Gravitational Waves for Third Time

by eaq on 6/1/17, 3:28 PM with 107 comments

  • by cletus on 6/1/17, 4:29 PM

    The numbers here are just staggering:

    - Black hole merger occurred 3 billion light years away

    - Two solar masses were converted to energy

    - Briefly 10^34 megatons of energy were released every second

    This is hard to intuitively wrap your head around because we think of space as constant. Something like this can distort space itself. Amazing stuff.

  • by smortaz on 6/1/17, 5:58 PM

    FYI - if you want to check out the data, the code, even an audio of the wave checkout:

    https://notebooks.azure.com/roywilliams/libraries/LIGOOpenSc...

    It's a Jupyter notebook that anyone can clone and run.

    [edit: updated link]

  • by mturmon on 6/1/17, 3:59 PM

    I was at a talk by Janna Levin, astrophysicist and author of a book Black Hole Blues that describes LIGO. (E.g., https://www.nytimes.com/2016/04/18/books/review-black-hole-b...)

    She gave a neat analogy between GWs, as sensed by LIGO, and an electric guitar. In the sense that a distant pluck on the string is transmitted as a wave down the string to the pickup, which senses a little wiggle in the string and amplifies it. I thought it was a poetic analogy that gives a second meaning to the word "instrument" in this context.

  • by eaq on 6/1/17, 4:08 PM

    The paper describing the event is available to the public at https://dcc.ligo.org/LIGO-P170104/public

    The instrument data of this event is also available to the public at https://losc.ligo.org/events/GW170104/

  • by wolfram74 on 6/1/17, 3:52 PM

    Anyone familiar with this branch of astronomy want to explain why one detection in a volume on the order of 27 billion cubic light years is reasonable? Are they still processing data and will find more events? Is the sensitivity highly anisotropic so the detection volume is significantly smaller? Or are events like this just really conveniently rare that we get about 1 every data gathering interval?

  • by netcraft on 6/1/17, 5:32 PM

    Great veritasium video about this latest wave: https://www.youtube.com/watch?v=NVKO7UCIlgs

    What is involved with increasing sensitivity I wonder? Is it purely lengthening the arms? or are there other advancements required?

    Hopefully one day we can have these things in space, isolated from noise and curvature of the earth and no need for vacuum equipment.

  • by gjem97 on 6/1/17, 4:27 PM

    > These are collisions that produce more power than is radiated as light by all the stars and galaxies in the universe at any given time.

    Astounding, especially given that these are happening at regular intervals in our "neighborhood".

  • by shortstuffsushi on 6/1/17, 4:23 PM

    Somewhat naive questions, as I know very little about astronomy. Do black holes "move?" How is it that they could merge if they're stationary, unless they're pulling each other in I guess? If black holes are indeed pulling in everything, does that mean the whole universe would eventually be one giant black hole?

  • by mudil on 6/1/17, 5:40 PM

    Here's what I don't understand.

    In the first detection, they mentioned that two black holes collapsed, emitted gravitational waves, and the resulting combined mass was less than then sum of two previous masses because energy was spent on gravitational wave generation. Hence it means, that due to gravitational interactions, objects leak mass. Now, we know that every object in the universe is gravitationally related to every other object, plus universe is expanding hence objects are constantly in flux with each other. The question is where all the leaked mass goes? Can this leakage account for dark matter? What about the space-time, does it function as a storage medium for this energy that now came from the leaked mass?

    Please explain...

  • by castis on 6/1/17, 6:40 PM

    When a gravitational wave hits the earth, does the planet oscillate in place for the duration, or is our position in the cosmos displaced, or something else altogether?

  • by nsxwolf on 6/2/17, 5:29 AM

    Does the calculation of how long ago this event occurred account for the speed at which the universe is expanding? Does it need to?

  • by nurettin on 6/1/17, 5:22 PM

    How does LIGO separate vibrations caused by a nearby truck from whatever reading that is required for gravitational waves?

  • by shawkinaw on 6/1/17, 9:00 PM

    This is awesome. I spent a summer in high school at LIGO Hanford (Washington), it's so cool to see positive results starting to come out of it.