All Questions
480
questions
13
votes
4
answers
7k
views
Can a black hole be explained by Newtonian gravity?
In the simple explanation that a black hole appears when a big star
collapses under missing internal pressure and huge gravity, I can't see
any need to invoke relativity. Is this correct?
- 1,436
-1
votes
2
answers
368
views
Is this alternate theory of gravity as cause instead of effect plausible?
I came across this video today on YouTube that presents an interesting alternate theory of Gravity and the "missing" matter in the Universe that Dark Matter/Energy theories try to account for.
If I ...
- 253
8
votes
5
answers
3k
views
Alternate layman's metaphors for illustrating curved space-time
The metaphor of a surface (typically a pool table or a trampoline) distorted by a massive object is commonly used as a metaphor for illustrating gravitationally induced space-time curvature. But as ...
- 5,145
3
votes
0
answers
137
views
Does Spacetime have a "This Side Up" arrow? [duplicate]
Possible Duplicate:
Does the curvature of spacetime theory assume gravity?
Forgive my naivete as I am not schooled in Physics or Mathematics.
I was watching NOVA's "The Fabric of the Cosmos" ...
22
votes
5
answers
28k
views
Stephen Hawking says universe can create itself from nothing, but how exactly?
Stephen Hawking says in his latest book The Grand Design that,
Because there is a law such as gravity, the universe can and will create itself from nothing.
Is it not circular logic? I mean, how ...
- 329
48
votes
9
answers
29k
views
Why is the gravitational force always attractive?
Why is the gravitational force always attractive? Is there another way to explain this without the curvature of space time?
PS: If the simple answer to this question is that mass makes space-time ...
- 1,772
-2
votes
1
answer
564
views
future light cones and light paths
I understand that an event, in a four dimensional space-time, produces a light cone. As time increases the cones gets larger on either side of the event (past and future). For example the if the sun ...
- 159
11
votes
3
answers
11k
views
Gravitational time dilation at the earth's center
I would like to know what happens with time dilation (relative to surface) at earth's center .
There is a way to calculate it?
Is time going faster at center of earth?
I've made other questions ...
- 2,909
5
votes
1
answer
2k
views
Voyager local time dilation (caused by gravity)
Voyager I, as an example, taking account gravity
and setting aside effects of speed as cause of time dilation.
If it is very far away from earth and sun,
so then there must be a difference in the ...
- 2,909
0
votes
1
answer
222
views
Is relativistic motion equivalent to fluctuating gravitational fields?
The theory of relativity makes very precise predictions about how an object's motion through space-time affects the passage of time for both the object and observers in other frames of reference.
I ...
- 109
-2
votes
1
answer
481
views
Space-time hospitality
Are there any reasons to assume that organic processes cannot arise in relatively flat spacetime environments? An argument for the existence of a critial value or window.
- 423
5
votes
5
answers
2k
views
How does the curvature of spacetime induce gravitational attraction?
I don't know how to ask this more clearly than in the title.
- 6,044
36
votes
8
answers
6k
views
Does the curvature of spacetime theory assume gravity?
Whenever I read about the curvature of spacetime as an explanation for gravity, I see pictures of a sheet (spacetime) with various masses indenting the sheet to form "gravity wells." Objects ...
- 6,044
0
votes
3
answers
1k
views
Space as "flat" plane
I was watching the documentary Carl Sagan did about gravity (I believe it's quite old though) and wondered about space being "flat" and that mass creates dents in this plane as shown at about 3 ...
- 6,927
81
votes
17
answers
59k
views
How exactly does curved space-time describe the force of gravity?
I understand that people explain (in layman's terms at least) that the presence of mass "warps" space-time geometry, and this causes gravity. I have also of course heard the analogy of a blanket or ...
- 913