“The years of searching in the dark for a truth that one feels but cannot express, the intense desire and the alternations of confidence and misgiving until one breaks through to clarity and understanding, are only known to him who has himself experienced them.” -Albert Einstein

In 2015, for the very first time, gravitational waves were directly detected from the merger of two massive black holes. These ripples in space traveled over a billion light years before they were finally detected. When they were, it validated Einstein’s theory of General Relativity in an entirely new fashion, and proved the physical existence of a phenomenon that was doubted even by Einstein himself.

Computer simulation of two merging black holes producing gravitational waves. Image credit: Werner Benger, cc by-sa 4.0.

In a stunningly well-researched and well-written book, Ripples In Spacetime, award-winning science writer Govert Schilling takes us on a journey that not only details how these waves came to be detected, but it puts the entire story in historical and scientific context. The past, present, and future of gravitational wave astronomy, plus what it means for humanity and the scientific endeavor, is brilliantly discussed.

An artist’s impression of the three LISA spacecraft shows that the ripples in space generated by longer-period gravitational wave sources should provide an interesting new window on the Universe. LISA was scrapped by NASA years ago, and will now be built by the European Space Agency, with only partial, supporting contributions from NASA. Image credit: EADS Astrium.

Come take an in-depth dive into what wonders this book holds — particularly if you’re a LIGO skeptic — and if you like what you’re reading, pick yourself up a copy and get the full story!


  1. #1 Pentcho Valev
    August 3, 2017

    “It’s also a bit shocking that the Pound-Rebka experiment, very simple in concept, was derided as too complex to describe for the book. Yet all that experiment did was cause a nuclear emission at a low elevation, and note that the corresponding nuclear absorption didn’t occur at a higher elevation, presumably due to gravitational redshift, as predicted by Einstein.”

    This is easy to explain. Perhaps Govert Schilling is just prudent – he knows (all clever scientists do) that the gravitational redshift was predicted by Newton’s emission theory of light, not by Einstein. Accordingly, the Pound-Rebka experiment is a confirmation of the variable speed of light predicted by the emission theory:

    University of Illinois at Urbana-Champaign: “Consider a falling object. ITS SPEED INCREASES AS IT IS FALLING. Hence, if we were to associate a frequency with that object the frequency should increase accordingly as it falls to earth. Because of the equivalence between gravitational and inertial mass, WE SHOULD OBSERVE THE SAME EFFECT FOR LIGHT. So lets shine a light beam from the top of a very tall building. If we can measure the frequency shift as the light beam descends the building, we should be able to discern how gravity affects a falling light beam. This was done by Pound and Rebka in 1960. They shone a light from the top of the Jefferson tower at Harvard and measured the frequency shift. The frequency shift was tiny but in agreement with the theoretical prediction. Consider a light beam that is travelling away from a gravitational field. Its frequency should shift to lower values. This is known as the gravitational red shift of light.”

    Albert Einstein Institute: “One of the three classical tests for general relativity is the gravitational redshift of light or other forms of electromagnetic radiation. However, in contrast to the other two tests – the gravitational deflection of light and the relativistic perihelion shift -, you do not need general relativity to derive the correct prediction for the gravitational redshift. A combination of Newtonian gravity, a particle theory of light, and the weak equivalence principle (gravitating mass equals inertial mass) suffices. […] The gravitational redshift was first measured on earth in 1960-65 by Pound, Rebka, and Snider at Harvard University…”

    Pound, Rebka and Snider knew that their experiments had confirmed the variation of the speed of light predicted by Newton’s emission theory of light, not the gravitational time dilation predicted by Einstein’s relativity:

    R. V. Pound and G. A. Rebka, Jr, APPARENT WEIGHT OF PHOTONS

    R. V. Pound and J. L. Snider, Effect of Gravity on Gamma Radiation: “It is not our purpose here to enter into the many-sided discussion of the relationship between the effect under study and general relativity or energy conservation. It is to be noted that no strictly relativistic concepts are involved and the description of the effect as an “apparent weight” of photons is suggestive. The velocity difference predicted is identical to that which a material object would acquire in free fall for a time equal to the time of flight.”

  2. #2 Alan G.
    The Galactic Empire
    August 3, 2017

  3. #3 CFT
    August 3, 2017

    LIGO’s supposed discovery is going BYE-GO…(that pesky little noise to signal ratio thingy…they still haven’t straightened out their story) and the Higgs discovery isn’t really that far behind (the particle isn’t a higgs). I’d be surprised if after the feathers settle if anyone was really that eager for funding “LIGO 2, The sequel in space!!”

  4. #4 CFT
    August 3, 2017

    There are no ripples Ethan, just computer generated noise matched to a pattern of something completely imagined and never observed. Before you go blathering about what was discovered, maybe you should just sit down and wait a while for the dust to settle on the so called ‘discovery’. You really e jumping the gun, just like with BICEP2.
    P.S. Ethan, space time does not ripple. It can curve according to Einstein’s math, but that is caused by a local source of mass that produces the curve, you and many others seem to be treating space time as if it can move like a medium or mediation force, as if it actually were a rubber sheet that could stretch or vibrate.

  5. #5 Elle H.C.
    August 4, 2017


    “There are no ripples …”

    We’ll see, Virgo joined LIGO in the science run on Tuesday, this months they will measure together. Afterwards all three detectors will go into another upgrade phase (for ~1 year) to improve the sensitivity.

  6. #6 CFT
    August 4, 2017

    @Elle H.C. #5,
    Yes, just throw more money at the problem. That should do the trick quite nicely…if you are trying to fund a perpetual physicist make-work employment machine. How about instead, some serious review and scrutiny of the testing methodology and a much shorter author list (Sorry, If you have 1000+ authors, you have little to no risk of actual accountability) should be required before further funding is provided. A lack of a straightforward explanation of why not one of the 1000+ ‘authors’ failed to discern their own signal from noise in their very own results does not exactly produce confidence with team LIGO.
    Please realize LIGO is already treading the same kind of ‘Doh!!’ incompetency waters BICEP2 disappeared into, namely, the experiment has more to do with a glorified ‘I want to see gravity waves’ Rorschach test than an actual scientific discovery. I’d laugh, but this sloppy psyche department joke has cost over a billion dollars (of taxpayers money) and still counting.

    They conclude:

    “It would appear that the 7 ms time delay associated with the GW150914 signal is also an intrinsic property of the noise. The purpose in having two independent detectors is precisely to ensure that, after sufficient cleaning, the only genuine correlations between them will be due to gravitational wave effects. The results presented here suggest this level of cleaning has not yet been obtained and that the identification of the GW events needs to be re-evaluated with a more careful consideration of noise properties.”

    LIGO has not refuted this dire conclusion.

    (In other ‘less long winded and cautiously walking back words’, NO, they did not make a discovery and detect gravity waves, just processing artifacts of their noise.)
    Maybe they could hire Ethan to paint a smiley face on this. He’ll have his work cut out for him.

  7. #7 Elle H.C.
    August 4, 2017

    @CFT #6,

    “It would appear that …”

    Therefor it is good to have Virgo and/or LISA to possibly debunk LIGO’s claim, and to check if or if not the lighting storm was the source. They might have fooled us … so we’ll see … and we no longer have to use weasel words.

    I don’t see the problem with the money, most of it flows back into the system, and the people getting it do little or no harm with their work, give them a little more credit. BTW Virgo is European so it are other people who are investing. They’re also expanding general know how and it’s good to have competition.

    Regarding the many people on the paper, I guess that’s because scientific research has become a lot more complicated. You could compare it to a watch, 100 years ago one person could build it on his own, now you have thousands working on an Apple Watch, everyone having some input and deserving some credit. Steve Job didn’t do it on his own … There’s no reason to be envious.

  8. #8 CFT
    August 5, 2017

    @Elle. H.C. #7,
    There’s no reason to be Envious?? Say what?
    Actually, if it wasn’t for Steve Jobs, there would be no Apple. No Bill Gates? No Microsoft. Sorry, but sometimes it takes someone to actually take charge and turn a bunch of people into a company that actually does something.
    “Regarding the many people on the paper, I guess that’s because scientific research has become a lot more complicated. ”
    Actually, no. No matter the size or complexity of the project, there still should always be a precious few who are responsible and who get the glory for success, or the ridicule of failure. This is what gets things done and prevents rampant mediocrity. When the ‘group’ is responsible, no one is, I learned this first hand in the fiasco of several ‘group projects’ in my physics classes that my teacher was using to try and instill the virtues of groupthink. I also learned if I didn’t take responsibility (and do the actual work myself in case my ‘comrades’ flaked out), nothing happened. I also made careful documentation of who did what, so when my teacher asked for our projects, I was VERY clear of who actually did and didn’t do what. I had no guilt whatsoever about calling folks out that I had warned multiple times that they needed to contribute or they wouldn’t get credit for the project while keeping the director, my teacher in the loop and informed (Little Red Hen in action). I have no respect whatsoever for the ‘We are all going to get credit’ mentality when no one steps up and takes responsibility, and in truth, in the real world (i.e. not academia or government work), when you don’t work, you don’t have a job for very long.
    When I told my father of my troubles with the group ‘project’ of equals, he laughed and explained this is why communism literally doesn’t work (he had firsthand experience about it, as he had lived under it until the Hungarian Revolution of 1956).
    A motion picture takes a lot of people too (watch the credits sometime), and there is ALWAYS a director and a producer at the top of the billing, followed by a few actors. Everything else is just a union contract required participation trophy of acknowledgement that even the onsite nurse, the best boy’s assistant’s assistant and they guy who brought their coffee get their names mentioned. Giving the junior plumber and the director …and everyone else equal credit in the film is just bad groupthink in inaction.

  9. #9 Ariel Paisley
    United States
    August 5, 2017

    The parallels between the behavior of waves in fluids and the behavior of waves in spacetime seem obvious to me. The two dimensional surface of the ocean appears spherical and smooth from mega-scales, yet the oceans are actually a composition of an infinite number of waves viewed up close. It stands to reason that spacetime should appear smoothly curved at mega scales and yet be infinitely active and complex at pico scales.

    Visualize waves propagating in four dimensions through spacetime which behave similarly to waves on a two dimensional pond surface and extend the observable phenomena from the pond surface to a four dimensional construct. These four dimensional waves are composed of infinitely complex sub-waves, so the surface of spacetime is rippled and rough when viewed from one scale and yet appears smooth from another scale.

    I suspect that expanding our imagination to hyper-macro scales is where we will find the answers we are seeking. The reason we can’t yet “close-the-deal” on a “theory-of-everything” is we are thinking way too small. The universe is vastly larger than most of us can imagine and we just can’t see around the corners of curved spacetime. Once we begin thinking at the correct scales, everything will fall together like a child’s jigsaw puzzle. We just can’t see it because we just can imagine that everything we can perceive in the entire universe is comparatively less than the relative size of a “sunspot” on the surface of a star.

  10. #10 Elle H.C.
    August 5, 2017

    @CFT #8,

    My comment wasn’t about leadership and/or groupthink, it’s just a fact that lots of people work on the project. Steve Jobs even asked at the end of his keynotes that the people who worked on ‘his’ projects to stand up, and so they were acknowledged. The same goes for LIGO there are leaders who are pushing this project further doesn’t mean that the little ones deserve some credit just like at the end of a movie.

  11. #11 Paul Dekous
    August 5, 2017

    If all light within a Black Hole moves towards the singularity, than why shouldn’t all the Quarks start doing the same, wich turns Protons into …

    Fact is we still need some serious proof that a BH is actually an object and not a hurricane-like phenomenon driven by forces from the outside … hurricanes can also merge just like ‘Black Holes’.

    The book might have a crucial flaw, just like the Solar system didn’t revolve around the Earth but the Sun, Galaxies don’t revolve around ‘Black Holes’ object, but around a calm ‘massless’ area …