Evidence that the key assumption made in discovery of dark energy is in error

Re:Evidence that the key assumption made in discovery of dar... by brylie on Monday January 06, 2020 @08:27PM (#21975771)

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.

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Re:Evidence that the key assumption made in discovery of dar... by knzhou on Monday January 06, 2020 @08:56PM (#21975945)

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

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Re:Evidence that the key assumption made in discovery of dar... by CoryG89 on Monday January 06, 2020 @08:41PM (#21975848)

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?

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Re:Evidence that the key assumption made in discovery of dar... by ncmncm on Monday January 06, 2020 @09:14PM (#21976085)

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.

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Re:Evidence that the key assumption made in discovery of dar... by 8bitsrule on Monday January 06, 2020 @09:55PM (#21976345)

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!

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Re:Evidence that the key assumption made in discovery of dar... by brylie on Tuesday January 07, 2020 @04:09AM (#21978289)

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

Scientists have even managed to freeze light for short periods of time.

https://io9.gizmodo.com/scientists-freeze-light-for-an-entir...

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Re:Evidence that the key assumption made in discovery of dar... by earthboundkid on Monday January 06, 2020 @08:50PM (#21975906)

Constant in a vacuum. Read about https://en.wikipedia.org/wiki/Cherenkov_radiation

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Re:Evidence that the key assumption made in discovery of dar... by shpeak on Tuesday January 07, 2020 @08:11AM (#21979580)

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.

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Re:Evidence that the key assumption made in discovery of dar... by brylie on Monday January 06, 2020 @08:31PM (#21975794)

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

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Re:Evidence that the key assumption made in discovery of dar... by shpeak on Tuesday January 07, 2020 @08:07AM (#21979557)

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.

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