"The short answer is that gravitons do exist, in the sense that there is theoretical evidence that they must exist, observational evidence that they do exist, and no good reason to doubt that they exist."
"While we don't have observations of a graviton, we do have observations which are completely consistent with momentum being radiated away from tight binary star systems in accordance with the theory of General Relativity, and therefore have evidence of gravitational radiation. To date, most other propagating momentum has been traced to quantized particle-like phenomena, including phonons in lattices and the gauge bosons of the Standard Model."
"The evidence comes from measuring the spin of an object called a "pulsar", which is supposed to be a spinning compact mass - a neutron star, perhaps. The pulsar orbits around a companion star that is nearby. The energy of the system was observed to decrease slightly over a time of several years. The decrease appeared to be consistent with the amount of decrease predicted by general relativity from the radiation of gravitational energy. We believe that if gravitational energy is radiated, then it must be radiated in discrete quanta. These quanta would be "gravitons". There is no direct evidence for gravitons to date."
I have an issue with gravitons which is, no doubt, due to my ignorance on the topic at hand. However, my undertanding is that the empirical observation described above can be explained solely in terms of gravitational waves. There is no need to invoke the idea of graviton just because of analogy with other parts of physics. Perhaps geometry of spacetime behaves diffently in this respect; perhaps the difficulties in marrying QM and GR are an indication of this.
Gravitational waves were predicted in Einstein's time and I'm pretty sure that gravitons were not needed in the gravitational wave description at that time. My point is that *perhaps* we are extrapolating empirical evidence too far if we say that the binary star observation supports *gravitons*. OTOH I have no doubt that gravitational waves are real because of the binary star observation.
Regards,
Antti
Antti Savinainen, Ph.D., B.Ed.
Adjunct Professor (University of Jyväskylä)
Senior Lecturer in Physics and Mathematics
Kuopion Lyseo High School
Finland
E-mail: <antti.savinainen@kuopio.fi>
Website: <http://kotisivu.dnainternet.net/savant/>
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Viesti on tarkastettu roskapostinsuodatus- ja virustorjuntaohjelmistolla.
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