Recent content by jobigoud

I think co-orbiting means the two bodies actually shares the same orbit. For example Jupiter and the trojan satellites.

I think the reasoning is sound, but the Hubble constant is not simply "slightly decreasing". For most of the time, the expansion has been much closer to linear than to exponential. If I understood correctly, what is observed is a slight acceleration from linear. With time, recession velocities...

Did you take into account the fact that as the device moves further away from the Sun towards the Venus orbit, its surface of incidence will decrease and it will not receive as many light than when it was at Mercury's distance ? Also, the sail being at an angle, it will not receive the full F.

Dark energy is not meant to explain the expansion itself, but rather the acceleration of the expansion.

Acceleration of the expansion means that the Hubble parameter is decreasing less rapidly than before. But it's still decreasing.

Sorry if it looked like so, but I was definitely NOT referring to him not mentionning acceleration. (I have realized that acceleration of expansion has confused me before, and find it easier to first work out the concepts without it anyway.) I was referring to the « velocities left over from...

I happened to read bits of this book last night. I think it's more critical than sloppy language. I've only ready Chapt 2, Expansion of the Universe, but there are several issues. He states several times that the recession velocity of very distant galaxies must be corrected to avoid going...

No, it is not believed that expansion has anything to do with a drop in gravitational forces. Gravitational forces are not observed to drop. In fact, locally, gravity counteracts the expansion : the Solar System does not expand. The expansion is only observed for objects separated by very...

I'll have a try at it. elapsed time = t1 - t0 If t1 is +∞, then elapsed time is also +∞, even if t0 is an actual value instead of -∞.

I am sorry if I'm going to add to the confusion for not understanding what you mean, but I think you had it right initially and that you are mistaken now. - The observed galaxy is indeed further away now that what we observe it to be. (if we measure it using the "lookback time") - It was...

I'm no cosmology expert, and I find the question interesting, however I think your logic is wrong here. We have the statement : "if nothing else is taken into account outside the Black Hole (A), then nothing can escape the event horizon (B)." You use this to infer that under different...

How convenient :biggrin: So I can say that God is actually a tiny invisible pink unicorn that lives under my bed, because, you know, since we are talking about something supernatural, any logical stretch is allowed.

It would seem that you guys do not use the accepted definition for the word "universe". Universe: The totality of everything that exists. It cannot be in something, or located. It is everything.

During its normal life, the nuclear reactions in the star's core creates outward pressure that compensate the gravity. It is only when the star has radiated most of its energy from nuclear reactions that it has trouble fighting gravity. Depending on its mass at this point, it may collapse to a...

I wasn't applying my instinct to general relativity but at trying to refute the proposition that if there had actually been an explosion of matter into space the effects wouldn't necessarily be distinguishable from expansion of space itself. This is what the original poster suggests, that the...