Does expansion of spacetime also stretch amplitude of light waves?

Click For Summary
SUMMARY

The expansion of spacetime stretches the wavelengths of light, resulting in a redshift, but does not affect the amplitude of light waves. Amplitude is unrelated to brightness in electromagnetic (EM) waves; instead, the intensity of light is determined by the number of photons collected by an observer. Telescopes utilize large mirrors to gather more light, enhancing visibility. The intensity of an EM wave correlates with the square of its amplitude, but this does not imply that amplitude stretching increases brightness.

PREREQUISITES
  • Understanding of electromagnetic (EM) wave properties
  • Familiarity with the concept of redshift in cosmology
  • Knowledge of wave-particle duality in physics
  • Basic principles of telescope optics and light collection
NEXT STEPS
  • Research the relationship between amplitude and intensity in electromagnetic waves
  • Study the principles of redshift and its implications in cosmology
  • Explore the mechanics of telescope optics and light collection techniques
  • Investigate wave-particle duality and its effects on photon behavior
USEFUL FOR

Physicists, astronomy enthusiasts, and anyone interested in the properties of light and the implications of spacetime expansion on electromagnetic waves.

SteveinLondon
Messages
10
Reaction score
0
Expansion of spacetime stretches wavelengths and produces the red shift. Does it also stretch the amplitude of the wave, and make distant stars look brighter and therefor nearer?
 
Space news on Phys.org
Amplitude has nothing to do with brightness in an EM wave. Intensity of a light source is dependent on how many photons you are able to collect. This is why telescopes use large mirrors that are able to collect many many times the amount of light than your eye. They then focus this down to a small area, resulting in a visible image.
 
SteveinLondon, you've posted this in two different places: here and https://www.physicsforums.com/showthread.php?t=484699 Please don't do that. It's inconsiderate. I've replied in the other thread.

Drakkith said:
Amplitude has nothing to do with brightness in an EM wave. Intensity of a light source is dependent on how many photons you are able to collect.

The intensity of an EM wave is proportional to the square of the amplitude. I think you're getting confused here by wave-particle duality. The wave stuff doesn't stop being true just because it's also a particle. If you consider a single photon, it has electric and magnetic fields, and the energy density is proportional to their squares.
 
Sorry about the double posting. It's the first time I've posted so not familiar with the protocol.
Does the amplitude get stretched? And therefor the intensity?
 

Similar threads

Graduate Is there a stretching of the light curves of supernovae 1a?
  • · Replies 5 ·
Replies
5
Views
3K
Undergrad Can gravitational waves gain energy in an expanding FRW spacetime?
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad How do you get to the conclusion that there is accelerating expansion?
  • · Replies 23 ·
Replies
23
Views
3K
High School Does a gravitational wave change the speed of light?
  • · Replies 7 ·
Replies
7
Views
3K
Graduate Speed of light/electromagnetic waves is constant?
  • · Replies 6 ·
Replies
6
Views
2K
High School Conservation of Energy and Expansion Redshift
  • · Replies 8 ·
Replies
8
Views
3K
Undergrad Is the fabric of space a "medium" for light?
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad How does the speed of light affect expansion acceleration?
  • · Replies 15 ·
Replies
15
Views
3K
Graduate Expansion by doppler (red) shift
  • · Replies 11 ·
Replies
11
Views
3K
High School Gravitational Wave Stretching: LIGO Arm vs Light
  • · Replies 5 ·
Replies
5
Views
2K