Gee, sorry. My interest in cosmology is very recent. I'll try to keep more up-to-date. Should have said "cosmological fluid," I guess. BTW, I believe the value of 77.3 KM/sec/mega-parsec for the Hubble constant came from a recent issue of "Astronomy," to which my stepson subscribes. (But I could...
Johninch,
Fascinating article, mostly over my head. But note that in the range of -5 billion years (light-years) to present, objects still appear to be slowing their recession velocity from us as time flows forward. I think I have a basic lack of understanding of time itself, maybe...
Thanks...
Thank you all for your thoughtful answers and references. I have looked at Ned Wright's paragraph in the link above, which for me raises more questions. I was thinking of our basic observations, assuming only speed of light and recession velocity (due to red shift), not even considering whether...
Perhaps I am missing something obvious, but here it is anyway.
Observation of an astronomically distant object is essentially observation of a past condition of the object, due to the fixed speed of light. And IIRC, the Hubble constant seems to say that all sufficiently distant objects recede...
Um, well, I know that if the tangential velocity of an object in an elliptical orbit is increased just as it reaches apogee, it tends to circularize the orbit at the distance of the apogee from the planet. So it seems to me that the inverse would be true... that if the object were slowed while...
Ranger, thanks again!
One more question... if the tangential velocity of an orbiting body is decreased in such a manner, what happens to its orbit's shape? If it was originally perfectly circular, does it become elliptic? Does the average distance to the body which it is orbiting decrease, i.e...
Thank you, ranger. So the planet "captures" the probe to some extent. In your example, then, I would guess that if the probe is accelerated by 2U, the planet must be slowed in its orbit around the sun by some minuscule amount, depending on its mass. I think this would be noticeable if the probe...
I have always wondered how passing into and out of a planet's gravitational field would result in a net gain in velocity. http://pluto.jhuapl.edu/mission/whereis_nh.php" is an example: the New Horizons Jupiter/Pluto probe using Jupiter to get 9000 km/hr speed increase.
It seems to me that...
A little (but not much) off topic: recommend you read Stephen Wolfram's "A New Kind of Science," in which he deals with our perception of randomness (among many other things)!
---- Bill
The problem I have with "a property of space" is that if space is not "nothing," what is it? I thought the Michelson-Morley experiment was supposed to have proved that space is in fact not an "Ether" that has properties, but rather that it is, in fact, the absence of anything at all. Granted...