World Science Scholars

2.5 Gravitational Wave Astrophysics

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    • Numerical relativity is a field of study that attempts to produce approximate numerical solutions to the Einstein field equations for various astrophysical situations, like black hole mergers. Until recently this was a very difficult task, with programs crashing well before they produced meaningful results. What do you think of the fact that Einstein wrote these equations but himself could not solve them except in greatly simplified cases?

    • Einstein didn’t have today’s mathematical methods and computers to solve the problem.

    • Well, just try to solve the complete (!) equations by hand and you’ll see pretty soon that you’ll run into problems. Even with numerical relativity it took some time and more sophisticated technology (both hard- and software) to finally come to some templates which are solutions of individually defined merging black holes. More templates, including neutron stars and mixed versions (BH – NS) and a larger bandwith of the involved masses are yet to come.

    • Yeah I think Gravitational Waves are the new astrophysical window to what we think as the Cosmos. Dear World Science U, I have questions for the Experts, these are here
      1. How can Gravitational Waves tell us about the existence of Extra Spatial Dimensions and of indeed Strings in String Theory??
      2. We need a theory for Quantum Space-time and a sophisticated theory of Quantum Gravity, my point is that I study Loop Quantum Gravity so how Gravitational waves can be described by Loop Quantum Gravity??
      3. Why a Gravitational Wave will fail to escape the Event Horizon of a Black Hole??
      4. If a Gravitational Wave will fail from escaping a Black hole, then how we observed those Gravitational waves.

    • Philosophically, has one to be able to solve self written equations? I think no as there are equations without solution, at this time.

    • The fact that he couldn’t solve the equations, although he wrote them, exemplifies how far ahead of himself he was. Even in his assumed errors, Einstein was correct. I respect the boldness and courage he exemplified in his work and thoroughness before publishing.

    • The gravitational waves are generated from a point in space just outside the combined event horizon when the two black holes emerge, hence the waves can escape. Nothing that is generated within the combined event horizon can escape. Given that all the mass of each black hole is concentrated at its centre, the event horizon is not an actual physical surface – it is simply a region in space. Hence, when the two event horizons of the colliding black holes merge into one, the central masses of each black hole must still be moving towards each other. Do they continue to spiral inwards towards a final merger? Presumably so, but we will never detect gravitational waves from that part of the collision.

    • It seems to me that he did not have the facilities that we have now to be able to solve those equations

    • I understand why LIGO cannot detect low frequency GW, the arms are not long enough to measure the change on the scale of the lengths of the arms. I understand why Pulsar Timing Array cannot measure high frequencies, the pulsar pulses shape and sampling is two broad. But why cannot (e)LISA measure together with the low frequencies also the high frequencies to cover the range of LIGO, too? What kind of noise is eLISA limited by in high frequencies?

    • As I am listening to the lecture, I can follow along, but don’t ask me to explain anything to anyone after! Einstein came up with a theory that could predict things he could not even understand. That blows my mind.

    • I think he was more aware of the process than the solution

    • Computers are not the best tools for doing math – they are great at approximation, often to a very precise degree. That said, those approximations work very well since physical measurement also has accuracy limitations. Knowing the error range is important here, and knowing this, and being able to create these simulations, makes the science more accessible and helps move it forward. That Einstein was not a great mathematician does not detract from his physics.

    • he was more of a theoretical person, he understood the process but not the entire solution

    • The ideas that Einstein formulated lead these discoveries, they are part and parcel. He may not have been able to solve these problems numerically, but directly contributed the materials required for others to further this work.”In great attempts, it is glorious even to fail.”- Vince Lombardi, perhaps Einsteins’ failure to produce the necessarily calculated data wasn’t because of his inability to do the math. It was the enormity of it; The sheer amount of calculations would have taken decades, lifetimes to compute.

      So we must remind ourselves, just as it took time to construct LIGO, and LISA, that all great things take time. After all, Rome wasn’t built in a day. And neither was the volume of scientific work that we have today.

    • Hello Ladies and Gentlemen,

      I think Einstein was very new to this topic and could not fathom the depth of it.

      His culture was mostly agrarian, traditional, and not innovative.

      He was a product of his times, nurture over nature.

      I would love to work at LIGO myself. The smootheness of the topic is very appealing.

    • A

    • Einstein’s mind’s eye could probably see the answers, so then he wrote down the questions. Which were relative relativities, similar to how you might see a solution as something you want to accomplish then research to find out how to get it done. See the end from the beginning, find the middle, then begin.

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