“Delay is the deadliest form of denial.” -C. Northcote Parkinson

Every massless particle and wave travels at the speed of light when it moves through a vacuum. Over a distance of 130 million light years, the gamma rays and gravitational waves emitted by merging neutron stars arrived offset by a mere 1.7 seconds, an incredible result! Yet if the light was emitted at the same time as the merger, that 1.7 second delay shouldn’t be there, unless something funny is afoot.

In the final moments of merging, two neutron stars don’t merely emit gravitational waves, but a catastrophic explosion that echoes across the electromagnetic spectrum. The arrival time difference between light and gravitational waves enables us to learn a lot about the Universe. Image credit: University of Warwick / Mark Garlick.

While your instinct might be to attribute an exotic cause to this, it’s important to take a look at “mundane” astrophysics first, such as the environment surrounding the neutron star merger, the mechanism that produces the gamma rays, and the thickness of the matter shell that the gamma rays need to travel through. After all, matter is transparent to gravitational waves, but it interacts with light all the time! 30 years ago, neutrinos arrived four hours before the light did in a supernova; could this 1.7 second difference be an ultra-sped-up version of the same effect?

The remnant of supernova 1987a, located in the Large Magellanic Cloud some 165,000 light years away. The fact that neutrinos arrived hours before the first light signal taught us more about the duration it takes light to propagate through the star’s layers of a supernova than it did about the speed neutrinos travel at, which was indistinguishable from the speed of light. Image credit: Noel Carboni & the ESA/ESO/NASA Photoshop FITS Liberator.

There’s no doubt that the first gamma rays from this neutron star-neutron star merger arrived after the gravitational waves did. But why? Find out on this week’s Ask Ethan!

Comments

  1. #1 John
    Baltimore
    October 28, 2017

    Joel Mills,

    Good question! Thank you!

  2. #2 Omega Centauri
    October 28, 2017

    I would imagine the neutrino signal ought to be comparable to that from a core collapse SN. What does the theory say? And how close would the event need to be (SN1987 was only a couple hundred thousand LY.) for detection.

  3. #3 Michael Mooney
    October 28, 2017

    General comment on this blog:

    “In with Bang!… out with a whimper.”

    Really?! As your blog dies (I know you like the language), you go out quibbling about that 1.7 second difference!

  4. #4 Mihir
    India
    October 28, 2017

    Hi Ethan,
    Please tell us something about Hoyel’s steady state Universe.
    How steady state Universe works?

  5. #5 dean
    October 29, 2017

    Because Mooney, the 1.7 seconds is factual. Nothing you write is remotely close to factual.

  6. #6 Steve Blackband
    October 29, 2017

    #3
    You quibble incessantly about something infinitely small when you say 0.999,,,,, isn’t the same a 1. 🙂

  7. #7 Steve Blackband
    October 29, 2017

    On reading about LIGO, a text said that when the black holes merged, ‘they radiated 100 times more energy than all the stars in the universe combined’.
    Is that right? Thats mind blowing.

    Also I asked if making the chirp ‘audible’ was misleading – I assumed they must have shifted down. But it seems the frequency is in the audible range so maybe its not so bad. They compare the chirps from different objects to an orchestra, LIGO will only detect ‘violins and violas’ and new devices are underway to hear more. The Europeans are building and underground version of LIGO with arms twice as long.

  8. #8 Steve Blackband
    October 29, 2017

    And then there is the space detector with satellites a million miles apart. Fun time to be alive!!

    Thanks Ethan for a great blog. Tell me where to go to follow your discourse.

  9. #9 John
    Baltimore
    October 29, 2017

    Steve Blackband,

    Where to go next: https://www.patreon.com/startswithabang

  10. #10 Michael Mooney
    October 29, 2017

    @dean #5: “Nothing you write is remotely close to factual.”

    Fact: The dimensions of physical objects and distances between them does not depend on how they are differently observed and measured, contrary to special relativity. The cosmos exists independently of all observation. the job of science is to accurately describe the world as it is, not to create an infinite variety of versions of it via differing observations, as relativity does.

    Fact: There is no evidence for an actual entity/medium “spacetime” which is curved by mass and guides the motion of masses, contrary to general relativity. Yet GR claims the above as fact, beyond criticism.

    Fact: There is no evidence for “Hawking radiation” by which black holes “evaporate,” contrary to the beliefs of all Hawking followers (including Ethan.)

    Fact: Nobody knows how old the universe is, because an eternally oscillating, “Bang/ Crunch” cosmos has not been ruled out, and no other model explains cosmic origin.
    Related fact: “Everything manifesting out of nothing” is a blind stupid appeal to magic. It did not all pop out of a Cosmic Magic Hat.

    Fact: personal attacks are not science.

  11. #11 Michael Mooney
    October 29, 2017

    @Steve Blackband #6
    First, I didn’t bring it up. Second, numbers are meaningless without referents in the world. Third, a very very very large and ever increasing PART of anything is still not the whole thing (represented by 1.)
    Ability to think and reason clearly is at least as important as a high degree of expertise in crunching numbers.

  12. #12 Steve Blackband
    October 29, 2017

    Thanks John.

  13. #13 Steve Blackband
    October 29, 2017

    #3 sounds like a personal attack to me.

    #10, “The cosmos exists independently of all observation.”

    How can you call that a fact when you cannot prove it i.e. cannot show it true unless you observe it?

    #11. I was winding you up – hence the smiley face. I thought it was funny 🙂

    Not not being funny: then again, tell me what is between 0.999… and 1 if they are different.

    I think we’ve done this to death. Signing off from this blog.
    It has been fun and informative.
    May the Bang be with you!!!!!

  14. #14 Michael Mooney
    October 29, 2017

    SB (even in your absence),
    My #3 was not science. Ethan’s focus on trivia ignores all major serious criticism, like my #10.

    If you believe that things cease to exist when not being observed you are in serious need of a reality check. Even if the universe were only 13.7 billion years old, it existed for quite awhile before being observed. But that is too philosophical/ reasonable for you.
    You seem to have ignored my answer in #11 to the stupid shit about a part being the same as the whole. Yes, it was done to death… until you resurrected it yet again.
    Bye.

  15. #15 dean
    October 29, 2017

    “Fact: personal attacks are not science.”

    That was not a personal attack – it was a statement of, well, fact. You continually object to things that experience and experiment support, and to theoretical conjectures of what might be, not because you have the ability to counter the physics with your own research or calculations, but because of your imagined offense to your third rate “philosophy of knowing” crap.

    “Second, numbers are meaningless without referents in the world.”
    Mathematicians from the past and the present are laughing at you.

    “Third, a very very very large and ever increasing PART of anything is still not the whole thing (represented by 1.)”

    And they are boggled by your inability to understand even the simplest of concepts.

  16. #16 Steve Blackband
    October 29, 2017

    Ah well.
    Its weird I think but I will actually miss MM.
    #14, I dont have beliefs, thank you. You do, without evidence, You think that by just thinking you know what happened before.
    I DONT.
    we have theories that we test and until shown otherwise….
    Crap. We don’t even know what 96% of the universe is made of.
    But by sitting around an jabber walking you can figure it all out.

    Sorry dude. Not gonna happen.

    You’re a 0.999,,,, thats for sure.

    Common now MM, THATS funny 🙂

    Have a good life my man. Its been a pleasure, for real.

  17. #17 Narad
    October 29, 2017

    numbers are meaningless without referents in the world

    Those “referents” are usually called “observers.” Anyway, does the Poincare group get to be sad here?

  18. #18 Michael Mooney
    October 29, 2017

    @SB #16: “#14, I dont have beliefs, thank you. You do, without evidence, You think that by just thinking you know what happened before.
    I DONT.”

    Are you sure you don’t BELIEVE that “philosophy is bullshit,” to quote a famous physicist? You avoided any dialogue on philosophy of science that I presented. You have no clue that epistemology is the bedrock foundation of science. (Just more mystical philosophy to you.)

    I do think (make that ‘know’) that the world must exist before it can be observed. Is that too philosophical?

    I know that the whole observable universe didn’t just pop into existence out of nothingness. That is religion, (“Let there be light!”) not science. The oscillating universe is the only alternative to such nonsense.
    The last word is yours if you want it.

  19. #19 dean
    October 29, 2017

    Wow Mooney, you are clueless about everything

  20. #20 Sinisa Lazarek
    October 30, 2017
  21. #21 Gerald Lane Summers
    October 30, 2017

    Mondays shall hereinafter be known as “Snark Day.”

  22. #22 Narad
    October 30, 2017

    General comment on this blog:

    “In with Bang!… out with a whimper.”

    Mirrors are your friends, MM.

  23. #23 Narad
    October 30, 2017

    You avoided any dialogue on philosophy of science that I presented.

    Was this the list of random assertions preceded with the word “fact”?

  24. #24 Narad
    October 30, 2017

    <

    Are you sure you don’t BELIEVE that “philosophy is bullshit,” to quote a famous physicist?

    I’m pretty sure that Frankfurt was misusing what should be a term of art, if that helps. Get cracking.

  25. #25 Michael Mooney
    October 30, 2017

    Final comments on the value (or not) of philosophy.

    Philosophy Is Bullshit:
    https://webhome.phy.duke.edu/~rgb/Philosophy/axioms/axioms/node34.html

    Many contemporary physicists continue to quote Hume. Nobody in physics has a patent on bashing philosophy, even though each physicist has one, lurking beneath their conscious awareness.
    Instrumentalism is Ethan’s avowed philosophy. Scientific realism is my choice for a science which intends to describe the world, not create multiple versions of it via our creative imaginations and theoretical speculations…
    … here known as established facts according to Ethan’s latest opinion.

    I hope Ethan gets a job as a science fiction advisor. (I heard he applied to the Star Trek franchise.) He would allow a lot of “creative license” for impossible fiction like time travel … and shrinking cosmic distances… and apply enough math to make it sound like science.

    Ps: It’s not just “snarky Monday.” Every day here at SWAB is a snarky swarm of mainstream INITIATES all over any who dare to criticize.
    I will not miss that.

  26. #26 dean
    October 30, 2017

    “Final comments on the value (or not) of philosophy.”

    That should be on philosophy as you see it, not as it is. The way you see it, just like the way you view science and mathematics, is ass-backwards and ignorant.

    You certainly will not be missed.

  27. #27 Narad
    October 30, 2017

    Many contemporary physicists continue to quote Hume.

    This seems extraordinarily unlikely. Maybe you should have preceded the assertion with ‘Fact:’. Have you even perused A Treatise of Human Nature? I haven’t much encountered the principle of association of ideas in the literature, although an understanding here sure as hell could prevent you from incessantly making a fool of yourself.

  28. #28 Narad
    October 30, 2017

    P.S. MM: Do delta functions exist?

  29. #29 Narad
    October 30, 2017

    P.P.S. MM: Is the Levi-Civita symbol a tensor?

  30. #30 CFT
    October 31, 2017

    Narad,
    The curtains have closed, the fat lady has sung, you need to go home now. Shoo.

  31. #31 Narad
    October 31, 2017

    The curtains have closed, the fat lady has sung, you need to go home now. Shoo.

    Poor baby. Remember, there’s always the “expanding Earth” approach to gravity if you get bored with the “electric universe.”

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