46 thoughts on “I keep a safe lab”

    1. Depends who’s counting. Creation Ministries would surely like to date it from the day they heard that the fossil was glued together!

  3. How could we possibly know? Does include the day lost when the sun stood still for Joshua?

  4. That is approximately the number of days earth has existed.

    Remember though, the day used to be shorter than 24 hours.

    1. Yes… then there are leap years – did dinosaurs have calendars?! I suppose all remnants of their advanced civilisation were wiped out at the KT boundary! Unless they all left in space ships until they could come back disguised as people…

    2. Actually, Bob… It’s about 65 million + 43 thousand years ago, near enough to the estimate of dinosaur extinction. Since the earth has apparently been around for about 4.5 billion years, that 65 million years is only about 1.4% of the days the earth has existed. (Ignoring the whole former 23 hours/day and leap years scenarios.)

  5. Well, that’s about 65 MYA. Wikipedia gives the extant dates for ‘raptors at 75-71 MYA…meaning that the last incident was several million years after the last ‘raptor was pinin’ for the fjords. Perhaps said incident was a case of a fossil falling on the worker?

    Oh — and they actually had feathers, and were the size of a large dog….

    b&

    1. If you use 70 MYA for last instance of Velociraptor and calculate using 365.25 days in a year (current), you get 25,567,500,000 days.

      If you calculate using 381 days in a year (approximate 23 hour days) – to approximate the shorter length of day back then, you get 26,670,000,000 days.

      Assuming the slowdown rate was constant (not sure if that’s a valid assumption), you could split the difference, and get roughly 26.1 billion days.

      1. 26.1 BDA is actually pretty close to the 23.7 BDA indicated, so they might actually have gotten the math right.

        One thing I’ve wondered…how constant has the Earth’s orbital period been? When there were 23 hours in a day, was the year 381 23-hour days long?

        b&

        1. Since the collision that formed the Moon, there haven’t really been any forces in effect that could appreciably alter the Earth’s orbit.

          The gradual lengthening of the day is due to tidal transfer of angular momentum from the Earth’s rotation to the Moon’s orbital motion. So the Moon is getting farther away as the day gets longer.

          1. But how do we know that?

            First, it’s not at all hard to imagine some passing rogue astronomical body making a high-speed swing through the Solar System. It needn’t be huge enough to totally disrupt planetary orbits; just enough to slightly change the orbit of either the Earth or Jupiter — perhaps just altering the eccentricity a bit, and orbital harmonics will dampen that out and probably, some millions of years later, only have resulted in slightly different orbital periods.

            Next, we already know that the Sun is losing mass at a rate of at least 5,000,000 tons per second…which I think works out to about one Earth mass every half million years. A couple hundred Earth masses is going to make a measurable difference in orbital periods, I should think.

            And we also know that orbits can set up all sorts of unpredictable wacky harmonics over those sorts of time scales.

            So I’m quite confident that the length of a year wasn’t the exact same number of seconds a hundred million years ago. Presumably it was more likely shorter than longer. But what’s the magnitude of the change?

            b&

          2. Perhaps we’re disagreeing over what counts as “appreciable”. I’m not going to quibble about a few seconds. But a change of 4-5% (as we see in the case of day length) is a different matter. If anything had perturbed the Earth’s orbit to that extent in the last 100 million years, I’m guessing we’d see lingering evidence of it (though I’m not an expert).

            As for solar mass loss, according to Wikipedia, the solar wind has carried away only 0.01% of the sun’s mass over its lifetime. The mass loss due to hydrogen fusion is of the same order of magnitude. So together they account for perhaps an hour or two of difference in year length over the Earth’s entire history.

            So I think the answer to your question “When there were 23 hours in a day, was the year 381 23-hour days long?” is likely to be Yes to the best of our knowledge (and rounding off to whole days).

          3. Hmmm…Wikipedia gives the mass-energy conversion rate as 4.26 million metric tons per second. That’s 1.3e17 kg/year. Times the age of the Solar System is 6.1e26 kg. That’s about 1/3000 of its current mass. It’s also almost exactly a hundred Earth masses (over the lifetime of the Solar System).

            So I obviously slipped a decimal or two somewhere (perhaps even in this post).

            I should probably quit while I’m confused….

            b&

          4. The day length has been seen, I think, in the magnitude of early tides and their effects on coasts. That magnitude is consistent with how the Moon formed closer and then its orbit widens as the tides brakes.

            If you work the numbers AFAIK at the time of Moon formation, some 4.5 Gy bp, the Earth day was 4-6 hours. I don’t have any references for that though.

          5. I forgot: this is one way to see how there hasn’t been any great disturbances in the mature system. Other ways is to look at debris disks and moons (not the captured retrogrades, obviously) for excess orbital “heat”.

            So, has something “just right” changed something (rotation) and then been damped out elsewhere? I think the answer would be “unlikely”. Maybe even “impossible”, but I don’t know enough orbital mechanics to say.

        2. Unfortunately I don’t have time to find the ref for this (altho I recall it was ca. 1961), but just to get it started, the spin of the earth has been slowing while the speed of the orbit is the same, so days have been getting longer, as noted above. This is what provided a crosscheck on geological age, from some fossil coral from a species that lays down layers daily, and with an annual periodicity. At the layer that was thought to be XXX millions old, there were something on the order of 400 layers in an annual cluster, as expected from calculating backwards to increased days/yr.

          Also, from a book I read about glaciation that a friend has not yet returned (au is EC Pielou, IIRC), there’s a periodicity of change in the angle of the earth’s spin, of something on the order of one degree, a periodicity of change in the coordinates of the ellipse of the orbit, and a periodicity in the point at which the earth is closest to the sun (right now it’s some time in the winter, so you’d think that when it changes to summer that would cook things, but it’s the opposite. It gets so cold when the earth is farthest in the winter that the closeness in the summer can’t compensate. Not surprisingly, there are names for all of these periodicities (cycles) but without the book they’re not at my fingertips.

          1. Before any Aussies jump in… Earth Perihelion is around Jan 2nd-4th in the Northern hemisphere winter 🙂

          2. This is what provided a crosscheck on geological age, from some fossil coral from a species that lays down layers daily, and with an annual periodicity.

            Ah — I do believe you’re right. I don’t remember where I heard that before, but it does sound distinctly familiar. And it would most certainly seal the deal.

            Thanks — and I’d appreciate anybody who could provide a pointer to the actual reference.

            Cheers,

            b&

          3. I can’t access the abstracts, but the observations seem to date back to the ’60s

            FROM HERE

            In an attempt to verify Wells’ [1963] determination of the number of days in the Devonian year, Scrutton [1964] found a grouping of growth lines on Middle Devonian corals which he related to lunar periods. He found an average of 30.59 growth lines grouped into bands and presumed that they represented the number of days in the Devonian synodic month. Scrutton and Runcorn [1964] used Wells’ estimate (399) of the number of days in the Devonian year to calculate that there were 13 synodic months in the Devonian

            THIS HERE is more at my level [I understand it]:-

            The coral “skeleton” grows because the animals deposit calcite every day they are alive. The activity temporarily stops at night because the animals live symbiotically with single-celled algae that need light to function. The daily layers are visible under a microscope, making it possible to count days, somewhat like counting tree rings to determine the passage of years.

            Species that live in temperate waters are subjected to seasonal variations in temperature, so winter growth is slower and the marks farther apart. Years are therefore easily distinguished among the series of growth lines. A modern coral would show us years consisting of 365 lines.

            Coral fossils living 400 million years ago (400 Ma) in the Early Devonian display years of 400 lines, and thus 400 days, proving that the Earth did indeed turn faster at that time. For corals that lived during the Upper Carboniferous (300 Ma), there are approximately 380 lines each year. The fossil record thus clearly demonstrates that Earth’s rotation has gradually slowed over time, and that it is still slowing down today

    2. The 60th term in the Fibonacci series below is 1,548,008,755,920

      0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, …

      Thus I assume it translates as “Happy 60th Birthday, Dad! The Rennards”

  7. Can’t we check against Bishop Ussher’s biblical chronology? That really is accurate for all purposes ..

    (whistles off into the distance …)

  8. Shoudld be about 26,041,255,230 days give or take a few thousand in order to be 71 million years ago and assuming a 1.7 millisecond per centry shorting of days

  9. It’s at least a century shy of 65,000,000 years, depending on what value you use for the year. If it were exactly 65 million, that’s 365.24159 solar days per year, which is too short; the mean tropical year is 365.2422, the mean Gregorian year is 365.2425, and the Julian year is 365.25. Of course, the day was shorter back then, meaning there were more days in a year, but that really throws it off.

    I think I saw somewhere that the KT event has been dated now to close to 66,000,000 years, so there’s that, too.

  10. If it is undercounting a little bit then that still works fine (assuming it doesn’t cross the K-P boundary). Velociraptor mingoliensis is from the Late Cretaceous and even if the youngest specimens are ca 71 million years old, a ghost lineage surviving a bit later would not surprise me.

  12. Doesn’t the clock start for “XX days since the last incident” when the lab opens? In that case, the time should be from when the PI first occupied the space.

    I realize that’s the boring answer … and doesn’t involve any paleobiology unless the PI is really, really old.

  13. You guys don’t get it. 71-70 mya is when they achieved intelligence and began hiding all traces of their continued existence. Taking their ambush hunter proclivities to the ultimate extreme. That last incident 23.7 BDA was just a slip up. They have perfected their uberstealth existence since then.

    Get it now? THEY ARE STILL HERE!

    And they are, of course, much more advanced than we are, and very hungry.

  14. I think the poster is some sort of standard issue. I see them around the labs in our building.
    Love the I F****ing Love Science web site btw.

  17. It’s precise, but it’s not very accurate (re extinction dates of Velociraptor).

  20. Variation on a theme

    This is a Godosaurus us free workplace.
    It has probably been over 13.8 billion years since the last incident.
    There have been claims of a Godowarus 3000 years ago leading armies into battle and some talk of a Godwhosawrus from time to time since then but these concepts have evolved into Godosappiyins. Researchers studying the Godowarus genus have now reclassified it under Godwhowasus.

    Some people attempt to worship the Jurassic God but others, who accept the changes evolution makes, serve a more civilized
    central management system.

Comments are closed.