ACG52

In an interview given (I think) in 1919, after the confirmation of Mercury's precession, a reporter said to David Eddington that only 4 people understood Einstein's theory of Relativity. Eddington was silent for a moment, and the reporter asked what he thought of that, and Eddington replied, 'I'm trying to think of who the other three are".

Einstein also stated that energy produces gravity. In Pohl's Hechee series, there was an ancient race who used Black holes as a refugee while they caused a cycle of the universe to build a universe more suited to their race. I was thinking of Alan Dean Foster's Flinx series, in particular Flinx Transcendent.

Able to leap tall conclusions in a single bound... If I've done the calculation correctly, (which I must admit, I doubt), then on earth, we would observe 99956 UTU.

There was a science fiction book where the ancient weapon left by the obligatory disappeared progenitor race was a concentration of light which was so 'dense' (remember, fiction) that the gravitational field generated by the energy formed a 'massless black hole' which of course was used against the ultimate Evil from intergalactic space.

Because gravity bends space/time and light will always follow the geodesic.

No, it doesn't.

Do you have reading comprehension problems? It was clearly stated that this was an example from Thorne's book.

You're right.................. I've reconsidered. No change.

Well, there is clearly no T in my name. Everything you've posted on this forum has been inane, illogical, and totally lacking in any kind of fact. You are one of those scientifically illiterate people who believe that their ideas are as good as those who actually know something about the subject. They are known as cranks.

I prefer this theory because there isn't any other which adequately and parsimoniously explains our observations of galactic structure, and this one does. Since dark matter (as theorised) does not interact with the electromagnetic spectrum, and that is our only way of making observations, it has not been 'seen'. We do have indirect observational evidence of the existence of dark matter in gravitational lensing observations. Are you one of these who believes actual knowledge gets in the way of your thinking?

There is no such thing as gravitational chain. Again, totally incorrect. Education in astronomy would help you.

I'm not sure how you manage to get that from MigL's description of Kip Thorne's 'time machine'. The point was, that given a wormhole with one end stationary and the other end in a spaceship moving at relativistic speed experiencing time dilation, you can set up a closed timelike loop.

Not really much at all. Although the BH at the center is estimated to have a mass of 3 million solar masses, that's not much at all compared with the 400 billion in the galaxy as a whole. And gravitation falls off as the square of the distance. The dark matter is theorized to exist in something of a halo surrounding and penetrating the galaxy.

It definitely 'Time Warps'. Thorne has a chapter on the use of a wormhole and a spaceship at relativistic speeds as a time machine. I'd be more specific but I loaned my copy to my son, so I'm unlikely to see it anytime soon.

The book is not available online. Google the title and see what you get.

Completely wrong.

A minor correction. The name of the book by Kip Thorne is Black Holes and Time Warps; Einstein's Outrageous Legacy.

I'm sorry, I didn't realize you were a seventh grader, or I wouldn't have been so harsh. Well certainly, keep it up. But as long as we're here, explain what you mean by 'pure darkness'.

At 200 million lightyears from a gravitationally bound system, such as the Virgo galactic group, of which our galaxy is a member, expansion happens, at the rate of 73 km/sec/megaparsec. Closer than 200 million lightyears to any galactic group, gravity overcomes expansion. Keep in mind, the universe is pretty damn big.

Are we defining matter as that which has spatial extent and inertial mass?

You know that this is simply pure nonsense, don't you? Have you ever gone outside at night. Have you ever looked up? Have you ever seen the stars? Have you ever seen the moon? And what the hell is 'pure darkness' supposed to be? Oh don't be silly. Have you ever studied physics of any kind beyond the high school level? Have you ever studied grammar beyond the elementry school level? I got my degree in physics over 30 years ago, and while I've never worked as a physicist, I continue to read. This is one of a cranks favorite sayings. Write a bunch of nonsense which means nothing, but has arithmetic symbols and then say 'prove me wrong'. It doesn't you nit. High relativistic speeds is the domain of Special Relativity. Never mind, every science forum gets quite a few like you. BTW, don't PM me any more if you're thin skinned. MODS, can we move this to the trash can now?

All right, is it just me, or did this make no sense at all?

No one is talking about star age verification. I was explaining something which you clearly misunderstand, to wit, the phrase 'star's age'. If you read the link on stellar nucleosynthesis, you will see that as individual stars age, they produce metals. But there are some things which are simply not meant to be.

It's not that gravity exactly compenstates, it completely overwhelms. It's not that the expansion is undetectable over distances of less than 200 million lightyears, it doesn't happen at all. It tries to, but it's like an ant banging up against a brick wall. The ant tries to knock it down, but nothing happens. 'Older stars' means stars of the previous generation. Stars that were created longer ago. They do not mean that stars lose metals as they age. To the contrary, as individual stars age they create metals via stellar nucleosynthesis. (Since you're a big fan of wiki, here's the link: http://en.wikipedia.org/wiki/Stellar_nucleosynthesis) And please don't confuse wikipedia with an education.

What is 'them'? The Earth-moon system? Cosmological expansion come into play at distances of 200 million light years. On scales smaller than that, expansion is overcome by gravity.