A Riddle for all members to solve (and the answer is NOT the first one you think of either btw),
" I was, I am, I always will be but no-one can actually reach or attain me."
WHAT am I?
The speed of light ?
Sorry but another Nope on that one as well. Keep on trying though please.
Nah, gravity’s speed beats the socks off c. LO-effing-L.
Coffeo and I were dealing with gravitational attraction between sun and earth, specifically, does gravity travel at speed of light and take ~8.3 minutes to reach earth?
From that, since the sun moves about the galactic center,
1 ) is earth attracted to where the sun is or to where the sun was 8.3 minutes ago?
2 ) is jupiter attracted to where the sun is or to where the sun was more than five hours ago?
@yvilletom No, not really since the Gravitational pull exerted by the Sun on the Earth is counteracted by the distance of the Earth from the Sun and the Centrifugal force the Earth experiences as it orbits the Sun.
Centrifugal forces ALWAY force objects to TRY to move OUTWARDS away from the centre and NOT towards the centre,
Basis Physic at work there btw.
LIGHT travels at approx. 186,000 miles per second, hence it takes, given that 1 Au (Astronomical Unit being the mean distance from the Earth to the Sun btw) is approx. 93,000,000 million miles it takes the light emitted by the Sun approx. 8.325 seconds for it reach the Earth, hence when one views the Sunrise it has already happened approx. 8.325 seconds ago.
Please, PLEASE do a bit of research and get the FACTS first.
@yvilletom But that calculation is ALSO dependent upon the position of the Earth in its orbit around the Sun since there are fluctuations in the orbital path btw.
8.325 minutes IS the average btw and dependent upon both the Orbital Fluctuations AND the point on the planets surface where the measurement/s are taken PLUS the Season at the time of measurement as well.
@Triphid, @yvilletom I do wish people would stop talking about gravity as if it were a force. I even heard an astrophysicist, who should have known better, talk about 'the force of gravity' on TV the other day. What she should have said was 'the effect of gravity. It isn't a force, and it doesn't travel. Gravitational waves travel, but it is not gravitational waves that hold the solar system together, it's just plain gravity. Always there, doesn't go anywhere. Therefore, NO SPEED.
@Coffeo The internet says the “no speed” idea is a product of an Einsteinian thought-experiment: general relativity.
Being a theoretical physicist, aka mathematician, Einstein made no hypothesis he could test. Nor has anyone else found empirical evidence for it.
Though it lacks evidence, many people believe it.
@yvilletom If you have the appropriate background, you will find the following article of interest:
[link.springer.com]
I freely admit that my mathematics isn't up to following it in detail (and probably never has been, even back in the days long ago when I gave first-year lectures on relativity). But it is nonetheless interesting. If you like, you can easily skip to the conclusions.
There is a more approachable article in Wikipedia:
[en.wikipedia.org]
@Coffeo So many words, so much mathematics, all based on Georges LeMaitre’s misuse of an Edwin Hubble hypothesis to support the Genesis story.
Without America’s fundamentalist xians, LeMaitre’s explanation would have died decades before the Soviets put a man into earth orbit in 1961 and started getting taxpayer support.
@Coffeo No.
I intended my “Nah, gravity’s speed beats the socks off c.” as humor. Your “Probably not” and my “Love it” would have ended our exchange but a visitor entered.
Your comment to both of us moved me to do a search I hadn’t done and I learned that GR is the source of your “no force” and “no speed” views.
Einstein’s biographer Isaacson described his need to rebel and I see SR and GR as pranks motivated by that need. Time will tell.
I once heard a Unitarian minister say his Sunday services were for people who haven’t kicked the church habit.
America’s race to the moon once provided me with a hefty salary, and the Standard Model provides salaries for tens of thousands of people. IMO, its lack of evidence and millions of words — along with scifi’s excitement — are for people who haven’t fully kicked religion.
@yvilletom I don't rubbish the standard model. It does a sterling job in those areas where it works, and anyone would be crazy to use GR in such cases. GR comes in when the standard Newtonian approach fails. GR passes all the tests, yet we know that it, too, must be incomplete. You don't need to rebel against GR, just don't use it when you don't need it. Or, in your case, just ignore it.