User talk:Tumpul

Welcome...

Hello, Tumpul, and welcome to Wikipedia! Thank you for your contributions. I hope you like the place and decide to stay. Here are some pages that you might find helpful:

Please sign your name on talk pages using four tildes (~~~~); this will automatically produce your username and the date. If you need help, check out Wikipedia:Questions, ask me on my talk page, or place {{helpme}} on your talk page and ask your question there. Again, welcome! Dan Beale-Cocks 11:27, 23 April 2008 (UTC)[reply]

Relation between black hole and time[edit]

Hi. I thought I would give you a quick answer to your question here, as I see it got deleted from the talk page. There is a relation, because gravity affects the rate of time, according to general relativity. The rule is that when you are "higher up" in a gravitational field (ie, potential energy greater), time runs faster for you (not only clocks, but all processes involving time), and slower for those lower in the field. Of course, since everything, every physical process (clocks, atomic vibrations, biology, the speed of computers, and the speed of neurological processes in your brain), is affected, you would perceive nothing abnormal in your immediate surroundings, but only notice that clocks lower down than you are running slow, and those higher up are running fast. Precision measurements of the vibration frequency of the nuclei of atoms carried out at Harvard in 1959 showed that time ran slower by a tiny bit (2.5 parts in 1,000 trillion!) in the basement of the physics building there than at the top of a tube filled with helium (to permit the easier passage of gamma-rays) running up 22.5 m to near the roof.

In a black hole, the effect is so extreme that time at the event horizon actually stops, in the sense that if you were to watch a clock deep down near the event horizon from a site entirely outside the field, you would see it slowing to a stop as it neared the event horizon. A person riding with the clock would notice no such effect, except that he would see your clocks (looking back out at you) as running faster and faster the deeper he went, seeing you racing far into the future. (This all assumes that he could escape being crushed or torn apart by the strong gravitational field deep down, which is possible in principle for a sufficiently massive black hole.) Cheers. Wwheaton (talk) 14:36, 23 April 2008 (UTC)[reply]