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Gravitational waves

Research done at Nikhef. Gravitational waves. Gideon Koekoek January 9 th 2008. Overview of the talk. Graviational waves: a revolution What are gravitational waves? Measuring gravitational waves What we @ Nikhef / Vu are doing Conclusions. Why gravitational waves?.

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Gravitational waves

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  1. Research done at Nikhef Gravitational waves Gideon Koekoek January 9th 2008

  2. Overview of the talk • Graviational waves: a revolution • What are gravitational waves? • Measuring gravitational waves • What we @ Nikhef / Vu are doing • Conclusions

  3. Why gravitational waves?

  4. Why gravitational waves? What is so interesting about them? We already have telescopes, neutrino detectors and stuff like that to study the Universe, right? So why do we want to measure gravitational waves as well?

  5. Theory: how correct is General Relativity? Astronomy: what is the nature of Dark Matter and/or Dark Energy? Astronomy: what processes occur in exotic objects? Cosmology: what happened after the Big Bang? Why gravitational waves? We need gravitational waves!! There are questions we cannot answer without GWs:

  6. This is us Why gravitational waves? What is the nature of Dark Matter/Dark Energy? Most of the Universe, we don’t know anything about! We need gravitational waves!

  7. Light can only see up to here ..neutrino’s can only see up to here.. ..but gravitational waves can see up to here! Why gravitational waves? How about the Big Bang? We need gravitational waves!

  8. What are gravitational waves?

  9. 1st Law: motion in straight lines if there is no force. What are gravitational waves? Wait, what is gravity in the first place? Gravity is a force! v F Earth’s path is not straight, but bent by a force

  10. Gravity is not a force; it’s the curvature of space (and time) What are gravitational waves? • Newton does not agree with Relativity, • All matter behaves the same under gravity Einstein disagreed.. Still a straight line, but in curved spacetime!

  11. This is a very small number! ~ 10-45 (!!) You need a lot of energy to curve spacetime; gravity is weak! What are gravitational waves? Q: What curves spacetime? A: energy does! Ok, good. Now about those gravitational waves..

  12. Flat spacetime, plus a little curvature What are gravitational waves? Curvature in the vacuum? A wave equation: a curvature hμυ oscillates through space!

  13. What are gravitational waves? An example: gravitational waves produced by a binary star system We want to measure these waves! Binary stars: source of GW’s Us

  14. Measuring gravitational waves

  15. 10-45 (!!) Measuring gravitational waves A blessing and a curse: GW’s interact very weakly Blessing: once produced, they can’t be disturbed Curse: very difficult to measure them ourselves!

  16. Note: a million times smaller than a proton! Measuring gravitational waves Amplitude and frequency of gravitational waves emitted by a binary system of masses M1 and M2 at separation r

  17. A: with an interferometer! Fabry-Perot cavities: increase the arm length Measuring gravitational waves Q: How to measure gravitational waves? Idea:if a GW comes by, the length of the arms is disturbed: phase difference between the arms →interference pattern

  18. LISA(US + EU) 5 106 km arms Launch: ~2015(?) Measuring gravitational waves These things actually exist! LIGO (US) 4 km arms VIRGO (EU) 3 km arms

  19. What we @ Nikhef/Vu are doing

  20. Management Theory of gravitational waves Hardware, data analysis,.… You? What we @ Nikhef/Vu are doing Nikhef has taken and carried out the initiative to start a research group focusing on gravitational waves

  21. Conclusions

  22. Conclusions • Gravitational waves are ripples in spacetime that travel with velocity c; • They can teach us a lot about binary star systems, Dark Matter/Dark Energy, the Big Bang.. etc etc; • Measuring GW’s is difficult; it can be done by using interferometers; • Nikhef is working (both experimentally and theoretically) on Virgo and LISA

  23. Conclusions Interested to do a Masters? Contact Tjeerd Ketel ( TJ.Ketel@few.vu.nl) or Jo van den Brand ( jo@nat.vu.nl) The end

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