Stephen Hawking's new way of perceiving black holes !

Post by **zong** » Wed Jul 21, 2004 10:35 pm

According to the theory of relativity, the laws of physics can only be applied on specific frames of reference, and not across time.

Also, I don't think acceleration has to do with what we're talking about. But anyway if you want constant acceleration, this means increasing velocity. However, at a specific frame of reference, B must have a definite velocity, say, x m/s. Since this is definite, then A must see the same x m/s when B travels. Agreeing on time only comes into view when B travels near the speed of light, since time dilation would be negligible at "normal" speeds.

I see where you're going, I think you're thinking of some inconsistencies in the theories of black holes you've read so far. Sometimes, these inconsistencies cannot be explained, or can only be proved with very complicated mathematics, and then also, it's only mathematics and not practically proven. So don't dwell on it too much

ChaosKnight · Post by **ChaosKnight** » Thu Jul 22, 2004 10:35 am

zong wrote: Also, I don't think acceleration has to do with what we're talking about. But anyway if you want constant acceleration, this means increasing velocity. However, at a specific frame of reference, B must have a definite velocity, say, x m/s. Since this is definite, then A must see the same x m/s when B travels. Agreeing on time only comes into view when B travels near the speed of light, since time dilation would be negligible at "normal" speeds.

I see where you're going, I think you're thinking of some inconsistencies in the theories of black holes you've read so far. Sometimes, these inconsistencies cannot be explained, or can only be proved with very complicated mathematics, and then also, it's only mathematics and not practically proven. So don't dwell on it too much

i prefer to think about it some more rather than lay off. If i still don't understand after that....well....nothing much i can do except ask around, or think about it some more.

Ok, i'm rather convinced observers travelling at different velocities will observe different magnitudes of acceleration. Can you, or anyone, confirm this?

Post by Q » Thu Jul 22, 2004 12:40 pm

ChaosKnight wrote:No, observation of same accleration is impossible (if my math is correct). My question is whether both observers see constant acceleration.

This question has something related to black holes, if i can find the correct link between these issues. Somehow.

looks to me that either
1. you copy the whole chunk of passage from a book or
2. you ripped off some other website...
haha
you dun answer your own questions in this way... btw how old are you and how 'good' is your maths?

ChaosKnight · Post by **ChaosKnight** » Thu Jul 22, 2004 1:43 pm

i'm very young, and my math is no good. That's why i'm asking for verification :oops:

Lets do a thought experiment.

Imagine two lamp posts, spaced apart.
There are two observers, A and B.
A stands by the road, while B is accelerating in a car.

When B pasts the first post, both A and B synchonise their watches and agree on the velocity.

When B past the 2nd post, again A and B agree on their velocities.

What they can't agree on is the time B took to travel from 1st post to 2nd.

Therefore if they are to agree on initial and final velocities, they cannot agree on acceleration. Acceleration is subjected to the time dilation factor as well.

If the admin allows, i could post a digital photo of my workings. And take my word for it: i haven't seen much equations on general relativity. Neither did i plagarise from the web or any book.

These opinions are my own and are likely wrong. If fact, there are certain aspects that don't seem to work out.

Post by **weixing** » Thu Jul 22, 2004 5:15 pm

Hi,

When B pasts the first post, both A and B synchonise their watches and agree on the velocity.

When B past the 2nd post, again A and B agree on their velocities.

What they can't agree on is the time B took to travel from 1st post to 2nd.

I don't see why they can't agree on the time B took from 1st post to 2nd post :?: :?: Unless time is slower or faster for A. If that the case, they of course cannot agree on acceleration of B.... I don't think you need to be very good in math to understand this

.

Have a nice day.

Post by **zong** » Thu Jul 22, 2004 6:18 pm

Time dilation doesn't bother you until your speed nears the speed of light.. so just take it that the time A observes that B travels from the 1st post to 2nd is the same time B observes himself to travel the same distance. So they WOULD agree on the time.

Just for your info if you want to know how much time dilation can affect you:

If a taxi driver drives at 60kph every shift and continues every day of the year for 60 years, he would be time dilated by roughly 1 second. That is how insignificant time dilation is, at "normal" speeds

Beware tho this is only a rough guide, not exact figures!

Post by **weixing** » Thu Jul 22, 2004 6:45 pm

Hi,
I think it is best that you create a new thread on this... It getting more and more off topics. If this continue, this thread will getting so long that it will be very difficult for others to track what are you asking initially.

By the way, please use a title that is direct related to the content.

Have a nice day.

gwenyi · Post by **gwenyi** » Thu Jul 22, 2004 6:57 pm

Information on blackholes are only tentative and so there are still lots of loopholes here and there. Although it is intriguing to study about that field, it can be quite confusing as well. So, another alternative is to try to understand as much as you possibly can, and not confuse yourself with other more complex theories that are also astro-related.

I believe it will take some time for one to grasp the ideas behind the theories...so.... dun rush. haha

cheers,
wenyi

Post by **weixing** » Thu Jul 22, 2004 9:06 pm

Hi,

time dilation factor

Oops... miss out this few words... Anyway, there is a formula for this that I seen in one book in Tampines Library... can't remember the book title.

Anyway, it a little too "deep" for me at the moment...

Have a nice day.

QuantumGravity · Post by **QuantumGravity** » Thu Jul 22, 2004 9:21 pm

I think there's a book called "advanced physics", which has a page with full of formulas ranging from newton's laws to relativity. If i'm not mistaken, the formulas of time dilation, length contraction, and all those stuffs are in that page....

Here are some that i remembered (hopefully i didn't get them wrong):

length contraction
[can't find symbol]1=[can't find symbol]0X/√1-v2/c2

final mass
m1=m0/√1-v2/c2

arghh... the subscript and superscript doesn't seem to work... anyway, i'll leave the formula there... zzz