# How do we know how far away and early in the universe galaxies are?

#### Pentcho Valev

"The expansion of the universe is causing galaxies to recede away from each other, with more distant objects moving away more rapidly. This results in the wavelength of light being "stretched"..."

This is one of the most preposterous cause-effect explanations in the history of science. Why should the expansion of the universe stretch the wavelength of light while failing to stretch anything else? Cosmological myths are immeasurably more preposterous than, say, flat-earth myths.

rod

#### rod

I note about the redshift, distance is only determined by using GR math and equations for the redshift number and applying H0 along with some other parameters. The cosmology calculators will show this.

There is the look back time distance commonly used when reporting distances in the BB model to the public for remote objects in the early universe. Each object with a redshift, also has the comoving radial distance. That is where the object would be today from Earth if it could be seen. Redshifts 1.4 or larger, are always farther away from Earth using the comoving radial distances then look back time distances and sit in space expanding faster than c velocity. Those two must be true in science, the comoving radial distances are much farther away from Earth than the look back time distances used, and space must expand faster than c velocity. Otherwise, the remote distances will unravel

Very tiny galaxy reports depend upon this as true, example. https://forums.space.com/threads/ja...-galaxy-packing-big-star-forming-punch.60953/

#### rod

"The expansion of the universe is causing galaxies to recede away from each other, with more distant objects moving away more rapidly. This results in the wavelength of light being "stretched"..."

This is one of the most preposterous cause-effect explanations in the history of science. Why should the expansion of the universe stretch the wavelength of light while failing to stretch anything else? Cosmological myths are immeasurably more preposterous than, say, flat-earth myths.
A good question. In GR, it is 4D space expanding and photons redshift as they travel through 4D space expanding. How this happens and atoms do not expand I do not know.

#### murgatroyd

Don't answer if the wife asks you "Does this redshift make me look fat".

COLGeek

#### finiter

Calculation of distance depends on two assumptions: Light follows straight-line path, and the redshift is due to expansion of space. If path of light has a very small curvature, say, the radius of curvature is about 2 billion light years, then the farthest will be the nearest. We cannot verify the straight-line motion for long distances. Redshift can be due splitting of high energy quanta into smaller quanta (in an expanding universe everything including radiations cools) in a time related manner. So, what Pentcho Valev said can be correct.

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