“While I can’t definitely say that gods don’t exist I am more certain that they don’t than I am that the sun will rise tomorrow.”

January 8th, 2014 in clues. Tags: , , , , , , , ,


My friend Gordon is an atheist and a reader of this blog. Recently in a comment on a previous post, he made the above comment.

It is still holiday time, I’m a nerd, and I enjoy a challenge, so I wondered whether I could analyse the science, and the belief. People with dedicated serious minds should turn away now!

What would stop the sun rising?

  1. The sun might cease via (a) natural processes, or (b) intervention by humans, aliens or God.
  2. The earth might also cease via (a) natural processes, or (b) intervention by humans, aliens or God.

Stopping the sun

Natural processes

Astrophysicists have classified our sun as a ‘normal’ star, one of about 90% whose physics and life cycle make it part of the ‘main sequence‘ of stars. They are therefore able to predict confidently that the sun will eventually (in about 6 billion years) expend its usable hydrogen, expand to become a red giant, then contract to become a white dwarf.

Scientists still debate the fate of the earth in this process, but it seems most likely that it will be destroyed as the sun expands – something more than 6 billion years into the future, and not before.

It should be noted that the sun is not of a size that it will explode, nor could a supernova close to our solar system destroy the earth.

So how probable is it that the sun will disappear by tomorrow morning? Because the main sequence contains the most common types of stars, its physics is well known, and can be described by equations and models that are well-supported by observations. The probability of these equations being wrong is very small.


Believe it or not, some scientists have seriously considered the possibility that the sun could be exploded by humans. Other scientists disagree it is possible, but regardless, it would take “centuries” to attain the capability.

The possibility that aliens or God could or would explode the sun is impossible to analyse (unless someone is more in the know than I am!). But a person who doesn’t believe in God should presumably also disbelieve in aliens capable of traversing deep space.


Is it possible to estimate a probability for the sun ceasing to exist by tomorrow morning? I have done it, though I don’t claim infallibility! If we assume that the probability of the sun not following the main sequence models has been constant over its life, we can say that if the daily probability of the sun not rising was 1 chance in ten billion, there was only 1 chance in ten million that the sun would have lasted this long.

We can conclude that it is extremely unlikely that the sun will cease to exist by tomorrow morning! I bet that’s a load off your mind! 🙂

Destroying the earth

Natural processes

Could the earth could be destroyed by a space object? NASA estimates that collisions that might put the earth’s population at risk occur several times every million years, but notes that “as best as we can tell, no large object is likely to strike the Earth any time in the next several hundred years”.

But even these massive collisions wouldn’t stop the sun rising, though they might stop anyone being here to see them.


Could humans destroy the earth? This website considers 10 ways this might be attempted, but, as this website concludes, it would take decades of hard work. It won’t be happening tomorrow.

As for aliens or God, the same applies here as for the sun. If you can’t believe in God, are you going to believe in aliens?


A similar calculation can be done as for the sun, giving slightly greater daily probability of the earth being destroyed (because it has been around slightly less time), but it is still true that the daily probability is minute. Don’t put off that visit to the dentist just yet!

The probability of God

What is the probability that God exists? There is no objective way (at present, at any rate) for us to assess this (as the man in black said: “anyone who says differently is selling something”). It’s all opinion.

The level of evidence required for anyone to believe or disbelieve must be proportioned to the strength of their belief or disbelief.

  • If a person is agnostic, they have no opinion either way that God exists, and they thus imply a 50/50 probability.
  • At the two extremes, a person who is certain that God exists, or doesn’t exist, would need to have absolute proof.
  • But most of us have opinions but not certainty, and we can reasonably be asked to offer evidence and logical argument appropriate to our level of belief or disbelief.

My evidence and arguments

I don’t claim certainty about my belief in God – I claim that there is good evidence to justify my belief that God’s existence is probable. This website contains that evidence – see e.g. Why believe?

Greater certainty about God than the sun rising?

We have seen that the probability of the sun not rising tomorrow is of the order of one chance in billions – an extremely sure bet! To be more certain that God doesn’t exist than that would require amazing evidence and argument. I haven’t seen it. And I’m not holding my breath!


No brain cells were harmed in the making of this blog post!


  1. @unkleE

    If a person is agnostic, they have no opinion either way that God exists, and they thus imply a 50/50 probability.

    It would serve you well to accept the definition of “agnosticism” from the inventor of the word, Thomas Huxley. Huxley was of the opinion that it was impossible to know for certain whether gods existed or not. He believed that this was the proper philosophical position. So agnosticism is a claim about the limitations of knowledge. Theism and atheism are claims to belief, (or its lack). Thus one can be, and usually is, both a believer or unbeliever and an agnostic. The definition says nothing about the probability of the existence of gods and indeed that’s the whole point. The contention is that such knowledge cannot be known.

    However, one argument is that once you endow your god with an incoherent property, such as omnipotence, it is reasonable to be a hard atheist, (that is certain), about the prospects of such a god’s existence.

    So, because I accept that I cannot disprove the existence of gods I am technically also an agnostic. However, if I must have a label, I think atheist is more appropriate.

    Does there have to be a reason for everything?
    I can’t believe it, (the universe), started without a cause.

    Only sentient beings have reasons. Therefor to assume that the universe came into being for a reason is to beg the question of a creator god’s existence.
    We do not know how the universe started, that is, why the big bang occurred. If time also started at the big bang that would preclude the first cause argument. Cause always precedes effect so without time the cause/effect idea is inappropriate. If we assume that time existed prior to the big bang parsimony tells us that God is an unnecessarily complex hypothesis as a first cause.

    It looks like it was designed

    This is generally called the anthropic principle although its original author now regrets the term preferring some name that would not infer specifically human intelligence.
    We cannot make such bald statements as:

    They have calculated that the probability of this, (the settings of physical constants), occurring by chance is so small as to be negligible.

    We simply do not know whether any other values are possible or whether an interdependence between the values exists. It is also impossible to calculate how many different values might exist which would lead to the evolution of intelligence.

    But if we assume for a moment that the values were set by a god. Why would he make the universe so hostile to the development of his favoured species? Why would he make its extinction so certain? Why would he be so profligate with the production of so many places that could never support life? If a disinterested third party came along and examined the universe he could be forgiven for declaring that life doesn’t exist at all. Even if life turns out to be quite common, say a million planets in our own galaxy with life, the percentage of mass in the universe that would be biomass is a tiny fraction of one percent. If you were aiming to create a universe for your favourite species you would do a much better job. In fact the universe appears just as we would expect it if there were no purpose behind it at all.

    Is there anybody in there? We think logically and make moral judgments about how to behave. If there is no God we cannot satisfactorily explain these things.

    This is a version of “You can’t have morality without God”. Of all the social animals only humans have gods. However moral behaviour has been observed in many other species. Morality came about, like all other animal traits, because it enhances the chances of survival of our genes. It does this by promoting social co-operation. Co-operating individuals can achieve so much more, including enhancing the chances of shared gene survival, than any number of rugged individuals following their own agenda. And of course while reason is an extremely potent addition to our survival armoury, our animal ancestors were making moral decisions on the basis of social instincts and emotions when they had little facility for reason.

    People all over the world report experiences of God – miraculous interventions, healings, guidance, visions of Jesus, a sense of God’s presence.

    If one were to accept reports of strange happenings as evidence for gods then one would have to accept the possible existence of pretty well every god that’s ever been proclaimed.
    Just as an example the average person’s inability to estimate realistic probability for events has been responsible for more claims of fantastic coincidence which must have been caused by divine intervention than anything else.

    So all in all your evidence for god is better explained by far more mundane and likely possibilities.

    You believe in a creature which:
    Has unknown origins.
    May have existed eternally.
    Has major magic powers.
    Has other properties not present in anything of our common experience.
    Exists outside space and time.
    Created the entire universe.
    Has a special interest in human beings.
    Offers eternal life to human beings who behave well and accept his godhood.
    Is a source of moral rules.
    On occasions communicates directly with humans.
    Inspired the writing of scripture in which he caused to be included valuable information for living a good life.
    And you don’t really know where all these claims about this creature originally came from.

    All this makes me even more sure that the idea that the sun won’t rise tomorrow is more likely than the idea that this creature exists.

  2. “All this makes me even more sure that the idea that the sun won’t rise tomorrow is more likely than the idea that this creature exists.”

    Hi Gordon, you are a surprising person! I think every other atheist I have discussed with believes philosophy is a very inferior method to science for knowing truth. But you believe your philosophising about coherence is more certain than a well established area of science.

    I don’t think there is anything I can say in response to such a belief, so I will simply thank you for reading and commenting. Best wishes..

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