Distant starlight causes problems for the age of the universe

How does Biologos explain the Horizon Problem? Is this also a modern theological dilemma given in medi-evil times the earth was considered the centre of the universe.

Distant regions of space in opposite directions of the sky are so far apart that, assuming standard Big Bang expansion, they could never have been in causal contact with each other . This is because the light travel time between them exceeds the age of the universe.

Interesting topic, Adam, thanks for starting it. On an aside, no one (other the BL staff) officially represents the BioLogos position on anything, not even the moderators. Everyone’s view here is their own. BioLogos is not a moment, tradition, or denomination in that regard. Just something to keep in mind.


The horizon problem is what inflation was specifically postulated to deal with. Some form of early (t<10^-12 s) exponential inflation seems to be a good fit for other properties (would have to check which) of the universe, in addition to uniform density and temperature. Exact properties of inflation are very speculative at present.

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Good question. Here is one source that gives a sorta simplified answer: WMAP Inflation Theory

As mentioned, BioLogos does not take sides on scientific disputes or unknowns, but rather affirms that science is a valid pursuit. From the Core Values on the site:

Rigorous Science — We affirm the established findings of modern science, celebrating the wonders of God’s creation.


It should be noted that, contrary to the claims of Answers in Genesis, the horizon problem is not the same as the distant starlight problem. That is a tu quoque argument, a false equivalence, a red herring, and an attempt to deflect attention away from the insurmountable problem that distant starlight presents to a young earth.

Comparing the distant starlight problem to the horizon problem is like comparing Mount Everest to a paperclip. The two concern scales that are separated by six orders of magnitude. The horizon problem concerns distances the scale of the entire visible universe, billions of light years in extent. The distant starlight problem concerns everything outside of a neighbourhood containing less than 0.5% of our own galaxy, the Milky Way. The horizon problem only has to account for a tiny fraction of a second of history after the Big Bang. The distant starlight problem has to account for 13.8 billion years of apparent history. The horizon problem concerns laws of physics that come into play right at the very limits of what we are able to measure and reason about, where there are still a lot of unknowns including for example the nature of dark matter and dark energy. The distant starlight problem concerns laws of physics that are well established and well within the extent of what we are capable of measuring and reasoning about. The horizon problem only has to account for an almost perfect initial uniformity of the cosmos. The distant starlight problem has to account for galactic collisions, relativistic jets, trails of gas hundreds of thousands of light years long, and evidence for numerous other specific events having happened at specific times with specific causes and specific effects over the course of 13.8 billion years.

The most widely accepted answer to the horizon problem is, as others have already stated, cosmic inflation. The distant starlight problem, on the other hand, has no workable physical solutions. However, even if inflation is not the correct answer and there is something else going on, that would do nothing whatsoever to significantly reduce the age of the universe from its accepted figure of 13.8 billion years. The horizon problem could be otherwise be accounted for by cosmic fine tuning—an explanation that is scientifically somewhat ad hoc, but that still acknowledges that the evidence that God has created is an accurate representation of what actually happened in history. The distant starlight problem requires the creation of evidence for events that never happened, and thus requires us to believe that the evidence that God has created is deceptive in nature.

Oh, and this is what the distant starlight problem looks like. It is an artist’s impression of the Milky Way, with a red circle representing a distance of 6,000 light years from Earth:


This statement is lifted directly from a NASA website.

When quoting verbatim honesty dictates providing a citation: WMAP Inflation Theory

edit: I noticed that jpm already posted this link

Thinking of speculative theory, I bumped into an interesting bit of speculation a while back that ties the heat-death of the universe to the beginning of the or at least a universe. If I can describe it correctly…

Ultimately the future of our universe appears to be one where all matter has been ‘caught’ by black holes and in turn those black holes all evaporate; thus all matter is gone. But it is the presence of matter that allows for measurement of anything meaningful, and thus there can be no measurement of anything in this future universe, including distance-- and if distance can’t be measured then there is no such thing as distance – and including time, since the only thing left is photons, and photons don’t experience time.
Thus, the argument goes, the universe has lost its metric; there is no difference at that point between a universe quintillions of light years in extent (or more) and one much, much tinier. So the universe essentially “forgets” that it is of immense extension and drops into a state of minimum extension, and thus all the photons in that massively extensive universe are found instead confined down to a Planck length.
But this density is an unsustainable situation, so the compressed universe ‘explodes’, for a brief period expanding much, much more rapidly than the speed of light, energy cools and becomes matter, matter forms into blobs and blobs differentiate into galaxies…

Supposedly the math on this leads to an inflationary universe just like what we actually live in without need for any “Big Crunch”, and makes it cyclic, too, though possibly with different natural laws in each iteration.

I know, that doesn’t help with the distant starlight problem that I can see, but it addresses the horizon problem by making it a natural aspect of any universe with sufficient gravity to pull everything into black holes and there is proton decay. (Though it bothers me that I don’t recall any mention of dark matter or dark energy in the scenario, I presume that the cosmologists who worked this up accounted for them.)

There might be some stable fundamental particles left in addition to photons, given the matter/antimatter imbalance. And what I’ve seen hasn’t suggested that all matter would end up in black holes, but that those would be the only large (macroscopic) structures left (assuming that protons decay).

That type of system might work, though.

I don’t see how this poses a problem for the age of the universe. As @jammycakes mentions, just the stars in our own galaxy tell us that the YEC timeline is wrong. We don’t have to venture far out into the universe to find galaxies that are millions of light years away. We can certainly see galactic interactions that would take long time periods.

Pointing to matter that didn’t interact with each other due to the initial inflation of the universe does not negate the interactions we can see, or the galaxies that we can see. Imagine what the night sky (or the sky during the day) would look like if we took all of the stars in the Milky Way and put them in a bubble with a radius of 6,000 light years. We would be fried in an instance. That’s without adding in all of the galaxies outside of our own.


Incidentally, we can now measure the distance to stars more than 6,000 light years away directly using stellar parallax. This relies on nothing more than basic trigonometry, and does not require “standard candles” such as Cepheid variables or supernovae.

From Wikipedia:

The Hubble telescope WFC3 now has a precision of 20 to 40 microarcseconds, enabling reliable distance measurements up to 3,066 parsecs (10,000 ly) for a small number of stars. This gives more accuracy to the cosmic distance ladder and improves the knowledge of distances in the Universe, based on the dimensions of the Earth’s orbit.

The European Space Agency’s Gaia mission, launched 19 December 2013, is expected to measure parallax angles to an accuracy of 10 microarcseconds for all moderately bright stars, thus mapping nearby stars (and potentially planets) up to a distance of tens of thousands of light-years from Earth. Data Release 2 in 2018 claims mean errors for the parallaxes of 15th magnitude and brighter stars of 20–40 microarcseconds.

40 microarcseconds of parallax corresponds to a distance of 25,000 parsecs, or a little over 80,000 light years. This means that we can measure distances to stars 10,000 light years away with an accuracy of ±10%, and we can tell with absolute certainty that there are other stars much further away than that.


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