6 ms·

I'm not an astronomer, but "tired light" makes more intuitive sense to me to explain the redshift. In effect, we already know that matter can affect light throu

by brylie 7y ago

I'm not an astronomer, but "tired light" makes more intuitive sense to me to explain the redshift. In effect, we already know that matter can affect light through gravitational interaction. Since light is travelling so fast and far it seems intuitive thst interstellar matter, as fleeting as it is, could act to slow light down over these great spacetime distances.

brylie 7y ago
According to the Wikipedia article, "tired light" has been discredited due to lack of observational evidence and assumptiins about light scattering: https://en.m.wikipedia.org/wiki/Tired_light https://en.m.wikipedia.org/wiki/Tired_light
- shpeak 7y ago
  Light scattering assumption is invalid, this is true, so photon losses energy because of an other mechanism. However, newer telescopes discovers more stars and galaxies than predicted by theories of expanding universe, thus favors Tired Light Theory. Also, discovery of gravitational waves confirmed that (speed of light in pure vacuum) c≠const, so physical vacuum is not an empty space, thus favoring TLT again.
CoryG89 7y ago
This doesn't make much sense to me. The speed of light is a constant, right? Gravitational interactions may change the directional component, but the speed would remain constant, no?
- earthboundkid 7y ago
  Constant in a vacuum. Read about https://en.wikipedia.org/wiki/Cherenkov_radiation https://en.wikipedia.org/wiki/Cherenkov_radiation
- ncmncm 7y ago
  It was expressed clumsily. The idea would be that photons can lose energy over time or space. One problem is that they would all have to lose energy at exactly the same rate as neighboring photons, so be a property of the space they are going through, not the photons themselves.
- 8bitsrule 7y ago
  The speed would remain constant; 'tired light' would shift to longer wavelengths (redden). Fritz Zwicky proposed the idea in 1929 - didn't work out. In 1933 he 'inferred the existence' of dark matter/energy, after using the averaged speed of a group of galaxies to calculate their mass ... and found they were producing too little light to have that mass. And there it sits a century later. MON Dieu!
- brylie 7y ago
  C is constant, which is the "speed of light in a vacuum." Light can, and does, travel slower than C, e.g. when traveling through gas or other material. https://en.m.wikipedia.org/wiki/Speed_of_light https://en.m.wikipedia.org/wiki/Speed_of_light Scientists have even managed to freeze light for short periods of time. https://io9.gizmodo.com/scientists-freeze-light-for-an-entire-minute-912634479 https://io9.gizmodo.com/scientists-freeze-light-for-an-entir...
- shpeak 7y ago
  No. Gravitational waves are causing fluctuations of speed of light in pure vacuum. (See LIGO/VIRGO experiments). So c is constant in steady physical vacuum only, i.e. it's speed of EM wave in medium. If you will change properties of medium, then c will be changed too.
knzhou 7y ago
Tired light is a very natural and intuitive hypothesis, it just doesn't work when you try to make it match up quantitatively.

by brylie 7y ago

brylie 7y ago

According to the Wikipedia article, "tired light" has been discredited due to lack of observational evidence and assumptiins about light scattering: https://en.m.wikipedia.org/wiki/Tired_light https://en.m.wikipedia.org/wiki/Tired_light

shpeak 7y ago
Light scattering assumption is invalid, this is true, so photon losses energy because of an other mechanism. However, newer telescopes discovers more stars and galaxies than predicted by theories of expanding universe, thus favors Tired Light Theory. Also, discovery of gravitational waves confirmed that (speed of light in pure vacuum) c≠const, so physical vacuum is not an empty space, thus favoring TLT again.

CoryG89 7y ago

This doesn't make much sense to me. The speed of light is a constant, right? Gravitational interactions may change the directional component, but the speed would remain constant, no?

earthboundkid 7y ago
Constant in a vacuum. Read about https://en.wikipedia.org/wiki/Cherenkov_radiation https://en.wikipedia.org/wiki/Cherenkov_radiation
ncmncm 7y ago
It was expressed clumsily. The idea would be that photons can lose energy over time or space. One problem is that they would all have to lose energy at exactly the same rate as neighboring photons, so be a property of the space they are going through, not the photons themselves.
8bitsrule 7y ago
The speed would remain constant; 'tired light' would shift to longer wavelengths (redden). Fritz Zwicky proposed the idea in 1929 - didn't work out. In 1933 he 'inferred the existence' of dark matter/energy, after using the averaged speed of a group of galaxies to calculate their mass ... and found they were producing too little light to have that mass. And there it sits a century later. MON Dieu!
brylie 7y ago
C is constant, which is the "speed of light in a vacuum." Light can, and does, travel slower than C, e.g. when traveling through gas or other material. https://en.m.wikipedia.org/wiki/Speed_of_light https://en.m.wikipedia.org/wiki/Speed_of_light Scientists have even managed to freeze light for short periods of time. https://io9.gizmodo.com/scientists-freeze-light-for-an-entire-minute-912634479 https://io9.gizmodo.com/scientists-freeze-light-for-an-entir...
shpeak 7y ago
No. Gravitational waves are causing fluctuations of speed of light in pure vacuum. (See LIGO/VIRGO experiments). So c is constant in steady physical vacuum only, i.e. it's speed of EM wave in medium. If you will change properties of medium, then c will be changed too.

knzhou 7y ago

Tired light is a very natural and intuitive hypothesis, it just doesn't work when you try to make it match up quantitatively.