Why is the night sky black?

Why does the night sky appear black? Why isn’t it white-hot? This is an important question.

When we look up on a moonless night, except for the small number of stars we can see with our unaided eyes (about 2500 at any one time), why is it so pitch black?  The answer may not be as obvious as you might think.

whyisthenigh

The blackness of space. Beth Scupham/flickr, CC BY-SA

The 19th century astronomer Olbers posed a paradox. If you imagine as you look out in space, even though galaxies and hence stars are great distances from each other, if space extends far enough, eventually every line of sight in every direction should finish on a star. If the Universe was infinite in size and filled with stars this would have to be the case. Thus why isn’t the night sky burning bright? Why isn’t it white-hot like the sun?

The situation is analogous to the situation if you found yourself at the centre of a forest. You can look all around and you see only trees. Wherever you look, your line of sight ends on a tree regardless of how far it may be. If the forest is dense enough and big enough you only see trees. You never see outside the forest where there are no trees.

There are several obvious resolutions to Olbers’ paradox for the Universe:

  1. The Universe is not infinite in extension (size) and therefore at the edge of the Universe stars cease to exist. Thus there should be many directions where you might look that do not end on a star.
  2. The Universe is finite in time. That means light from some very distant galaxies, and hence stars, has not reached us yet. Thus most of the universe is not yet within our visual horizon. Usually this assumption assumes the Universe is infinite in size.
  3. The Universe is expanding. If expanding then light from very distant galaxies has had its wavelengths stretched so much (i.e. redshifted) that the wavelengths are shifted down to become radio waves, which are extremely weak and invisible to our eyes.

Explanation #3 is nowadays considered the definitive answer. It goes with the belief that Edwin Hubble, with his observations of the ‘recession’ of nearby galaxies, in 1929, proved the Universe is expanding. Hubble measured the redshift and distances to nearby galaxies, alright, but it is not a proof that the Universe is expanding.

Six years after his publication (in 1929) Hubble wrote that he was not sure about an expanding universe explanation for redshift of galaxy light.1

“…the possibility that red-shift may be due to some other cause, connected with the long time or distance involved in the passage of the light from the nebula [galaxy] to observer, should not be prematurely neglected.” (emphasis added)

I once believed the Universe was expanding and I thought there was a basis for that in the Scriptures. But I now no longer believe that that is the case.2,3  Subsequent to that I developed a biblical creationist model4 wherein the Universe is static or quasi-static and redshifts (those for galaxies that follow a Hubble law relation, at least) are the result of ‘tired light.’5  Similar to what Hubble was suggesting in 1935, light loses some energy due to its long passage of travel from distant galaxies.

So the black night sky is not necessarily sufficient evidence for an expanding universe and the big bang origin of the Universe, as some claim.6 Besides, explanations #1, finite size Universe and #2, the Universe with a finite past time boundary (i.e. created at a specific moment in the past) are both valid arguments. One caveat on #2 is that #1 can be simultaneously true. Explanations #1 and #2 are not mutually exclusive.  Explanation #1 is only rejected nowadays because of modern cosmological philosophy. Explanation #2 is a problem for atheists (and those who follow them) for another reason. The very notion of a beginning at a finite time in our past logically implies a first cause for the Universe, an eternal Creator, who Himself is without cause. But the atheists must reject that so they seek a theory for an eternal big bang universe.7,8

The Universe is probably static (Psalm 148:3-6) and probably finite in size (Psalm 147:4). Our Galaxy is probably roughly near the centre of the finite Universe. The latter is based on some observational evidence,9 but more so on the fact that we were created by God and He has a purpose for this great Universe we see.  Also the Universe was definitely created at a past moment in time.

Redshift

Redshift is the measured shift in spectral lines from stars and galaxies. Here they are shown (top frame) shifted towards the red end of the spectrum compared to a laboratory sample (bottom frame).

My most recent model though would have redshift being observed in a similar systematic way to that from the alleged big bang cosmological expansion model (i.e. redshift proportional to the distance to the source). But in my model it results from ‘tired’ light.5 That means the light from the very distant galaxies has lost so much energy its wavelengths have been shifted down to wavelengths that are invisible optically. Add to that a finite number of stars implied by a finite sized Universe and you would not expect to see anything but blackness from Earth at night, apart from a few stars—just what we do see.

But there is more to it than that. There was no big bang. The Universe was created by God and He had very good reason to create the Universe the way He did. So the answer to Olbers’ paradox is clear. It is only a paradox to the materialist who can’t see anything more than matter and energy, space, time and the laws of physics. The Creator created the Universe with the intention of creating life on Earth and so He made it, and the laws of physics, such that the night sky was black.  Humans and all life need the night. It is a very important design feature.We must sleep to regenerate and that includes the important function of brain cell repair.10 So the black night sky is evidence of a Creator, not evidence of the big bang expansion.

References

  1. E. Hubble and R.C. Tolman Two methods of investigating the nature of nebular red-shift, ApJ, 1935, 82, 302H.
  2. J.G. Hartnett, Scripture and a static universe biblical creationist cosmogony, November 27, 2015.
  3. J.G. Hartnett, Does the Bible really describe expansion of the Universe?  April 14, 2014.
  4. J.G. Hartnett, A biblical creationist cosmogony, January 15, 2015.
  5. J.G. Hartnett, Speculation on redshift in a created universe, February 13, 2015.
  6. R. Barlow, Why is the night sky black? The Conversation, December 2, 2015.
  7. J.G. Hartnett, An eternal big bang universe, February 26, 2015.
  8. J.G. Hartnett, An eternal quantum potential or an eternal Creator God, January 17, 2016.
  9. J.G. Hartnett, Our Galaxy near the centre of concentric spherical shells of galaxies, May 26, 2015.
  10. H. Whiteman, Sleep ‘regenerates brain support cells’, medicalnewstoday.com, September 4, 2013

Related Reading and Viewing

4 thoughts on “Why is the night sky black?

  1. Hi Dr. Hartnett,
    Why not use/reference The Pearlman SPIRAL as explained in ‘Distant Starlight and the Age, Formation, and Structure of the Universe’ i sent you a couple of weeks ago to peer review to explain the cosmological redshift, instead of tired light?
    That explains why not only is cosmological redshift (CR) not due to ongoing cosmic expansion, but is empirical evidence of a cosmic inflation epoch, which was preceded by, or coincided with, stellar formation.
    It also explains why CR is empirical evidence of YeC as it falsifies all deep time dependent scientific hypotheses.
    best regards,
    r

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    • I read through your article ‘Distant Starlight and the Age, Formation, and Structure of the Universe’ but I have decided not to write a review because, with respect to you and your desire to honor God, which I applaud, I found that it made no sense to me at all. I could not find any actual physics in the article. And I did find several wrong statements as well as contradictory ones. Like the notion of a static universe but an inflation period. Even your statement above “… not only is cosmological redshift (CR) not due to ongoing cosmic expansion, but is empirical evidence of a cosmic inflation epoch,…” is contradictory. Cosmic inflation IS cosmic expansion. Maybe it is no longer ongoing, but even then you must show what would be seen by an Earth observer considering the canonical speed of light (c). Best regards.

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  2. Do you hold to conservation of energy in your model? What happens to photon energy over long distances in your model?

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    • Yes, energy is conserved in the Universe, and the energy lost by ‘tired’ photons is to the vacuum of space. The very process of bare photons being absorbed and re-radiated by the virtual particles of the quantum vacuum is the mechanism that causes them to travel at the canonical speed, c. I speculate that it also results a very small loss.

      A more recent paper (Urban et al. 2013) however, provides support for the idea that the finite speed of light (c) is determined by an interaction with the ephemeral particles in the quantum vacuum. This occurs at the sub-atomic Compton wavelength energy scale. The photon travels at a bare infinite speed between interactions with fermion pairs in the vacuum, which slow its progress to speed c. Such an idea was once suggested by Dicke (1957).

      Quoted from Speculation on redshift in a created universe.

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