Effects of gravity throughout space-time?

In summary: An alternative to dark matter is "modified" gravity, where gravity is assumed to work differently, but in such a way that it is only noticeable over large distances.
  • #1
TrentonF
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TL;DR Summary
Because spacial and temporal dimensions are the same, and gravity affects space, would the effect of gravity extend through time?
Can the effects of gravity possibly extend through time? Is there a natural law that forbids this?

Could this be a possible explanation for dark matter?
 
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  • #2
TrentonF said:
Summary: Because spatial and temporal dimensions are the same, and gravity affects space, would the effect of gravity extend through time?

Can the effects of gravity possibly extend through time?
Well, yes, space and time are linked and gravity acts on both and objects/fields travel/extend through both.
Could this be a possible explanation for dark matter?
No, this bears no relation to dark matter.
 
  • #3
TrentonF said:
Summary: Because spatial and temporal dimensions are the same, and gravity affects space, would the effect of gravity extend through time?

Can the effects of gravity possibly extend through time? Is there a natural law that forbids this?

Could this be a possible explanation for dark matter?

Gravity is determined by the geometry of spacetime. In fact, you could say gravity is the geometry of spacetime.

Gravity influences the motion of particles and radiation.
 
  • #4
russ_watters said:
No, this bears no relation to dark matter.
Isn't dark matter just an unidentified force of gravity that holds galaxies together?

If galaxies are held together by their own gravitational influence and that of a past state, could this not reasonably be an explanation for the excess of gravitational forces observed in galaxies?

Or is this already taken into account when determining the forces required to hold together a galaxy?
 
  • #5
TrentonF said:
Isn't dark matter just an unidentified force of gravity that holds galaxies together?

If galaxies are held together by their own gravitational influence and that of a past state, could this not reasonably be an explanation for the excess of gravitational forces observed in galaxies?

Or is this already taken into account when determining the forces required to hold together a galaxy?

If gravity behaved that way we would already see that in terms of the effect of the Sun's gravity on Earth etc.

An alternative to dark matter is "modified" gravity, where gravity is assumed to work differently, but in such a way that it is only noticeable over large distances.

You could search for MOND if you are interested.
 
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  • #6
TrentonF said:
Isn't dark matter just an unidentified force of gravity that holds galaxies together?

If galaxies are held together by their own gravitational influence and that of a past state, could this not reasonably be an explanation for the excess of gravitational forces observed in galaxies?

Or is this already taken into account when determining the forces required to hold together a galaxy?
There's 2 options:
A. There's matter in galaxies that we can't see.
B. We don't understand gravity as well as we think.

Scientists believe it is "A". Given how good the theory has worked relatively locally, it would be tough for there to be something major working differently at long distances.
 
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  • #7
russ_watters said:
Scientists believe it is "A". Given how good the theory has worked relatively locally, it would be tough for there to be something major working differently at long distances.

Some scientists believe "A" and some believe "B" and many are agnostic. The data is constantly coming in and generally speaking, tilting the balance away from A and towards B, although not necessarily decisively, and most of the early dark matter particle models involving SUSY WIMPs have been all but ruled out.
 
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Related to Effects of gravity throughout space-time?

1. What is the role of gravity in space-time?

Gravity plays a crucial role in the structure and behavior of space-time. It is responsible for the curvature of space-time, which determines the paths of objects moving through it.

2. How does gravity affect the motion of objects in space-time?

Gravity causes objects to move along curved paths in space-time. The strength of gravity depends on the mass and distance of the objects involved, and it can either attract or repel objects.

3. Can gravity be observed in space-time?

Yes, gravity can be observed in space-time through various phenomena such as the bending of light, the orbit of planets around a star, and the formation of galaxies. These observations provide evidence for the existence and effects of gravity.

4. How does gravity change in different regions of space-time?

The strength of gravity can vary in different regions of space-time due to the presence of massive objects. In areas with higher concentrations of mass, gravity is stronger, while in areas with less mass, gravity is weaker.

5. How does gravity affect the expansion of the universe?

Gravity plays a significant role in the expansion of the universe. It slows down the expansion by pulling matter together, but it is ultimately overcome by the universe's expansion due to dark energy. This delicate balance between gravity and dark energy determines the fate of the universe.

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