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The Gravitational Constant could conceivably not be a constant. Experimental measurements are over the map - most only agree on 3 - 5 significant digits of accu
by spacejoe 11y ago
The Gravitational Constant could conceivably not be a constant. Experimental measurements are over the map - most only agree on 3 - 5 significant digits of accuracy.
- greglindahl 11y agoNote this text from Wikipedia: "Under the assumption that the physics of type Ia supernovae are universal, analysis of observations of 580 type Ia supernovae has shown that the gravitational constant has varied by less than one part in ten billion per year over the last nine billion years.[13]" The ref is: J. Mould; S. A. Uddin (2014-04-10), "Constraining a Possible Variation of G with Type Ia Supernovae", Publications of the Astronomical Society of Australia 31: e015, arXiv:1402.1534, Bibcode:2014PASA...31...15M, doi:10.1017/pasa.2014.9 It's not the first paper to look into that issue, either! Always fun to remind people that physics involves more than what happens inside the lab.
- spacejoe 11y agoYet we don't have a high precision value for it. From the same Wikipedia article: "Published values of G have varied rather broadly, and some recent measurements of high precision are, in fact, mutually exclusive.[4][6]"
- AnimalMuppet 11y ago> the gravitational constant has varied by less than one part in ten billion per year over the last nine billion years. Um, that adds up to 9/10, doesn't it? That means that in ten billion years, it could vary by nearly a factor of 2.
- unabst 11y agoThis. Constants don't come first. Experimental measurement does. It's not like constants are backed by anything. They are what they are because they're always the same no matter how many times we measure them. If they changed, they wouldn't be constants. They are free to change. The one's that haven't just haven't.