The Sun, Electromagnetic Waves, and Gravitational Waves

Click For Summary

Discussion Overview

The discussion revolves around the interaction between electromagnetic waves and gravitational waves, particularly in the hypothetical scenario of the sun suddenly moving. Participants explore how changes in the sun's position would be perceived from Earth, focusing on the timing of light and gravitational wave detection.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether we would first see the sun move or detect a change in our orbit if the sun were to jerk from its position.
  • Another participant notes that light takes approximately 8 minutes and 20 seconds to travel from the sun to Earth, suggesting that any observation would be delayed by this time.
  • Some participants assert that changes in both gravity and electromagnetism travel at the speed of light, c.
  • There is a discussion about the components of electromagnetic waves and whether gravitational waves have analogous components, with some suggesting that gravitational waves have two independent components corresponding to their polarizations.
  • One participant mentions LIGO's purpose in detecting gravitational waves and questions whether gravitational waves are still theoretical due to a lack of detection.
  • Another participant responds that gravitational waves travel at c and are not affected by the mass of the object or the warpage of space-time, drawing a comparison to how light interacts with electric and magnetic fields.

Areas of Agreement / Disagreement

Participants express differing views on the nature of gravitational waves and whether their speed is influenced by mass or space-time warpage. While some agree on the speed of gravitational waves being c, the implications of this and the theoretical status of gravitational waves remain contested.

Contextual Notes

There are unresolved assumptions regarding the hypothetical scenario of the sun moving and the implications of gravitational wave detection. The discussion also reflects varying levels of understanding about the nature of gravitational waves compared to electromagnetic waves.

mef51
Messages
23
Reaction score
0
This is a question about electromagnetic waves and gravitational waves.

Let's say we're on the Earth and we're looking up at the sun (safely).
If the sun were --for some reason-- to violently and dramatically jerk from its position, how would we first find out?

Would we first *see* the sun move?
Or would we first detect a change in our orbit?

Would the light, the electromagnetic wave, reach us first, or would the gravitational wave reach us first? Would they happen at the same time?
 
Physics news on Phys.org
I don't know a situation where the sun would jerk from its position but I'm fairly sure that it takes around 8 minutes and 20 seconds for light to travel from the sun to Earth, so you probably wouldn't notice anything until that time had elapsed.
 
Changes in both gravity and electromagnetism travel at c.
 
mef51 said:
This is a question about electromagnetic waves and gravitational waves.

Let's say we're on the Earth and we're looking up at the sun (safely).
If the sun were --for some reason-- to violently and dramatically jerk from its position, how would we first find out?

Would we first *see* the sun move?
Or would we first detect a change in our orbit?

Would the light, the electromagnetic wave, reach us first, or would the gravitational wave reach us first? Would they happen at the same time?

Same.
 
Electromagnetic waves have an electric field component and a magnetic field component that are orthogonal to each other.
Is there something analogous to this with gravitational waves?
 
mef51 said:
Electromagnetic waves have an electric field component and a magnetic field component that are orthogonal to each other.
Is there something analogous to this with gravitational waves?

Not to my knowledge. I believe the wave is in the metric and only has one "component" if you will.
 
Gravitational waves have 2 independent components of the metric corresponding to the 2 possible polarizations.
 
Matterwave said:
Gravitational waves have 2 independent components of the metric corresponding to the 2 possible polarizations.

I assume this is different than the electric and magnetic components of an EM wave?
 
It is different - but you can compare it to two orthogonal polarizations of light.
 
  • #10
mfb said:
It is different - but you can compare it to two orthogonal polarizations of light.

Got it.
 
  • #11
Matterwave said:
Gravitational waves have 2 independent components of the metric corresponding to the 2 possible polarizations.

LIGO (Laser Interferometer Gravitational Wave Observatory) was built to detect such waves...but as far as I know, they have not found anything. So at this point gravity waves are still theoretical...right?
 
  • #12
FeynmanIsCool said:
LIGO (Laser Interferometer Gravitational Wave Observatory) was built to detect such waves...but as far as I know, they have not found anything. So at this point gravity waves are still theoretical...right?

I'd say so. We expect to find them as GR has been right about most observed effects so far, but we just haven't been able to locate the suckers yet!
 
  • #13
Drakkith said:
Changes in both gravity and electromagnetism travel at c.

Wouldn't the speed of a gravitational wave depend on the mass of the object, (in this case, the sun) and the warpage of space-time?
 
  • #14
Physicist50 said:
Wouldn't the speed of a gravitational wave depend on the mass of the object, (in this case, the sun) and the warpage of space-time?

No, gravitational waves travel at c. They are in the metric itself and not affected by it. Kind of how light isn't affected by electric and magnetic fields, it just goes right through them.
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 3 ·
Replies
3
Views
6K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 14 ·
Replies
14
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
1
Views
1K
  • · Replies 31 ·
2
Replies
31
Views
4K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 5 ·
Replies
5
Views
4K
  • · Replies 5 ·
Replies
5
Views
3K