Quality of the extrapolation leading to billions of years

I have just finished reading “The Language of God” by F Collins and considered it constructive and challenging reading; I am now at this web site (for the first time) as a consequence.

In Chapter six of the book F Collins presents a time scale by comparing the age of the earth (4.5 G-years) to 24 hours and states that the life of a middle aged person today would represent the last m-second of that 24 hr period. As I read this I was reminded of my struggle to come to terms with the quality of the extrapolation used to predict the age of the earth. Using the 24 hr time scale the scientific measurements used to predict the age of the earth have been occurring during the last few m-seconds. The number of m-seconds in a 24 hr period is in the order of 10 to the 7 hence the extrapolation is also in the same order which, according to my understanding of extrapolation, is unacceptable. The prediction that the “Big Bang” occurred at a time in the order of 10 to the -7 (that is, at the beginning of the 24 hr time period) and then occurred in an order of time 10 to the -40 of a m-second (ref: Chapter three of the book) contradicts all that I understand about extrapolation.

As an engineer my understanding of extrapolation might be too limited or narrow so I would appreciate feedback from the scientists.



Does it help that much of the human canon on cosmic physics seems to apply to the movement of planets, stars, solar systems and galaxies that we study millions of light years away … and thus millions of years away?

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So to be clear, because I am also a little limited on my knowledge, your question is basically that those numbers are way too huge and way too far apart to accept as satisfactory?

Hi @GCS, I wish you a very warm welcome here on the BioLogos Forum. Firstly, I want to applaud your way of using this Forum :slight_smile: . Such questions are basically what this place was made for.

The estimated age of the Universe does not depend on a simple extrapolation of processes that occur today. If that were true, that extrapolation could indeed be quite untrustworthy.

Different fields converge on this issue, but I’ll give it a try by providing you with a few examples from astronomy, my own expertise.

Currently, we understand pretty well how stars develop throughout their lifetime and where they get their “fuel” from. We understand how long stars typically live, depending on their mass. When we look at our own galaxy, we find thousands of stars of all different ages (younger stars are blue, older stars are red). So, by taking one look at our galaxy, we probe the whole spectrum of ages of stars. It can be compared to looking at a population of people. You can understand the age range of human beings from 0 till 90 years in a single moment, without any “extrapolation”. A star as heavy as our Sun typically lives for about 13 billion years. The current estimated age of our sun is about 4.6 billion years. We can find many younger and older brothers of our Sun, ranging from “new born babies” to dying stars (they often explode when they die).

Another way how we can study the past without “extrapolating” anything, is based on the finding that light needs time to travel. So when we look very “far away”, we are also looking at older parts of the Universe. It’s almost like a time machine. We can study processes that occurred a very long time ago, simply by looking at more distant objects. What is interesting here is that if we look at more distant galaxies, we also see that they relatively more “blue”, indicating that they have younger stars. This is logical since more distant galaxies were relatively young when their light started its journey towards us.


I think Collins’ description was used to convey a sense of proportion or scale to the age of the universe and timing of events like the formation of the Earth, the emergence of life and one’s own lifetime. That sort of ‘wall clock’ description has been used in many depictions about how vast time is. And actually, the time since the Big Bang is probably less than a drop in the ocean compared to future events like the heat death of the universe and the ultimate decay of matter.

Similar comparisons of scale can be used to describe the relative size of atoms or humans to the size of the solar system, the Milky Way galaxy and the universe.

Aside: It’s so much easier if one can intuit logarithms.

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Thank you for the helpful feedback so far. After finding the time to carefully consider it all I expect that I will be returning for more.

@gbrooks9 Thank you for your concise feedback. Does the issue I raised relate primarily to the field of cosmic physics? Your feedback addresses another issue I have struggled with, that is, reconciling millions of light years (which is obviously indisputable, scientific measurement) with the “young earth” approach but I will pursue that at a later date.

@Casper_Hesp Thank you for the welcome to BioLogos; feedback so far indicates that I am going to find it very helpful. Is it correct that this thread will be closed after three days of inactivity? After closure for how long will it be displayed on the web site?

@Sau5er5 Thank you for seeking clarification. It is not necessarily that the numbers are “way too huge” but that the orders of magnitude are incompatible with the time over which they are being extrapolated. If, for example and in simple terms (for my sake not yours), a linear relationship is being predicted then two co-ordinates measured milliseconds apart could not be accurately used to predict a third co-ordinate 24 hrs (or order of magnitude 10 to the 7) away.


@GCS the moderators won’t close this thread until it appears the conversation has ended. And it won’t be deleted.

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Another welcome, and a housekeeping note: If you ever want to continue discussion on a thread that has been closed, you can hover over the white space on the right hand sidebar near any post in the thread and an option “Reply as linked topic” will appear. This pulls the content of the post you are hovering over to a new thread, which you can rename something like, “Continuing the discussion about XYZ” and the new thread will be linked to the old one. If you want certain posters from the first thread to join the new conversation, you can tag them by typing @ and the first few letters of their user name until the whole thing pops up and you can click on it. Then they get a notification that the new thread exists.


Suggesting that terrestrial physics are somehow a special, and/or TEMPORARY, condition of Natural Law - - somehow apart from the vastness of Cosmic Physics - - simply because you question how something so temporally TINY could reliably represent the vastness of the Universe … is like proposing the likelihood that we should expect that a very small amount of sugar loses its sweetness the more of it you gather.

Don’t hesitate to ask more questions or to request reading material on specific issues. There are many different lines of evidence that all converge on an ancient universe, so there’s a lot to investigate. See for example, this BioLogos article: http://biologos.org/common-questions/scientific-evidence/ages-of-the-earth-and-universe. It also has a list of suggested readings on the bottom.

hi gcs. here is an interesting example: a simple calculation give us no more then 15,000 years for the first human. the current population doubling time is about 50 years. lets say that in the past it was even 1000% slower because of wars, diseases and so on (one doubling in about 500 years/ 500 years to get from 10 people to 20). so we need only 30 doubling to get to the current size. or 15,000 years.

so extrapolation may indeed be true- or false.

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…definitely false in this case, since what you did was just insert an arbitrary (and for that matter still incorrect) factor - the ‘1000% slower’ - just to land at the necessary conclusion: 15000 years.

true. but my point is that its actually fit with a young earth.

There are rational extrapolations and there are dodgy ones. GCS was wondering about the rational extrapolations behind dating measurements that have been back-checked, validated numerous ways and widely accepted by knowledgeable experts in the many fields the research covers.

And then there are others, like dscccc’s ‘Compatible with young earth’ extrapolations, which are not consistent, do not agree well with the overwhelming preponderance of data, are not remotely justified by historical or archaeological knowledge and are proposed primarily to rescue a dogma.

Let’s take a comparable dodgy extrapolation: Given E. coli replication rates, how old can humanity be?

E. coli has a wet weight of ~1E-12 grams
The mass of the Earth is ~ 6E27 g

To reach the mass of the Earth, E. coli would have to double 132 times.

E.coli has a minimal doubling time of 20-30 minutes under optimal conditions. Assuming a doubling time of 30 minutes, a single E.coli could replicate at a rate that would equal the Earth’s mass in just over 66 hours or less than three days.

In humans, the E. coli doubling rate is about on the order of 24 hours. At that speed E.coli could achieve an Earth mass in less that 4.5 months.

A back of the envelope calculation suggests that there is probably less than a mole (6E23) of E.coli bacteria currently on Earth within humans. A culture of E. coli would only need to divide 79 times to reach that number of cells. With a 24-hour doubling time, that would be 79 days.

It is currently, March 31, 2016. Extrapolating (stupidly) on the basis of E. coli reproduction rates, humans must have come into existence after January 10, 2016 which was 79 days ago.

Furthermore, we can readily predict that the human race will become extinct before May 23, 2016, when E. coli will have converted the entire mass of the Earth into bacteria.

QED: The entire duration of human existence can fit within a span of 5 months. Not quite consistent with Last Tuesdayism perhaps, as January 10 fell on a Sunday, but close.


For an extrapolation to be valid, the quantiity being extrapolated must be governed in its entirety by a mathematical equation whose coefficients together with their uncertainties are known over the entire range covered by the extrapolation.

Do historic rates of population growth meet these criteria?

do radiometric methods meet these criteria? i think the answer is no. because we cant know what happaned in the past.

hey argon. first- we cant use this argument with bacteria population because bacteria can reach the population limit very fast. humans in the other hand still doesnt get to the population size limit.

secondly- even if its not the case, you just prove my point that extrapolation mean nothing. so why do you think that radiometric dating (that also base on extrapolation) is a solid science?

[quote=“dcscccc, post:18, topic:4700, full:true”]
hey argon. first- we cant use this argument with bacteria population because bacteria can reach the population limit very fast. humans in the other hand still doesnt get to the population size limit.[/quote]

The issue is with your proposal of the human population starting with two or a handful of individuals only a few thousand years ago. In your instance it’s not the end point but whether the extrapolation backwards to starting conditions is valid.

In your example, like the one I presented on E. coli, the assumptions are not valid.

Records of ‘modern’ humans go back about 195,000 years. Evidence of ‘modern behavior’ (e.g. art and other traits), goes back at least 100K years. From at least 100K to about 3K-4K years ago, archaeological studies provide estimates of global human populations remaining between 3-10 million individuals.

A population’s limit is a function of the environmental carrying capacity (the ‘environment’ including the effects of the population itself and competition), and the ability of the population to exploit the resources. These are not constants: Environments change, competition changes and organism change.

Evidence of sophisticated stone tool use spreading through groups appears around 65K years ago. Homo sapiens dominated over Neanderthals in Europe around 45K years ago. Around 25K years ago an ice age seems to have slowed human population growth outside of Africa. However, population bounced back as ice melted and when agriculture – a hugely significant innovation – spread. It was agriculture and the ability to support large cultural centers to spawn additional innovation that probably drove the subsequent growth spurts.

Throughout the majority of human existence, there is no indication that human reproductive capacity was the rate limiting step in human population growth. Given that and the long time that humans sustained continuous populations in the 3-10 million range indicates that humans did bump up against their population size limits under the environmental conditions they encountered and with their abilities at those periods.

My E.coli example, establishing a population start date of sometime last January based on known double rates, is wrong because like humans of the past, E.coli have also reached population limitations within their hosts.

secondly- even if its not the case, you just prove my point that extrapolation mean nothing. so why do you think that radiometric dating (that also base on extrapolation) is a solid science?

This only demonstrates that naive, unchecked, unvalidated, extrapolation can be misleading.

Solid science checks the assumptions, seeks to understand the influence of potential confounding factors and learns to mitigate them, validates the steps, and carefully extrapolates between points within valid ranges of certainty.

You have succinctly addressed the issue of I have been struggling with. Although my experience with the mathematical process of “curve fitting” is very limited it has seemed to me that “curve fitting” has been used to scientifically, predict the age of the earth and that the curve (or mathematical function) has been extrapolated from known points to a point well beyond them, to the order of 10 E 7. That is the type of extrapolation I was referring to and is a type which seems unacceptable to me. Is it valid to consider that such extrapolation has been applied?

Is it valid to consider that such extrapolation has been applied?

In short, no.
There are numerous measurements, physical phenomena and correlated observations behind the numbers. Further, different phenomena and tools are used for different scales but are tested for correlation to demonstrate consistency.

This is discussed in a short Q&A section from Biologos here. There are additional references that go into much greater detail in the article’s footnotes.

One point to also note is that if YEC assertions about the age of humans, the Earth and the universe are true then there would have to be many orders of magnitude of errors in our understanding of various processes and rates. In short, the largely coherent and well established theoretical bases of modern physics and chemistry would have to be substantially rewritten and scrapped for YEC proposals to be right.

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