Radioactive dating

[dad1]

The basis for dating using ratios of isotopes is faith based. One example is that if we see an existing amount of parent and daughter material together, it is assumed that the present processes at work today are wholly responsible for all the material.

[Sherlock Holmes]

[Replying to dad1 in post #19]

This is all true, and far from controversial except to a few individuals I sometimes encounter who for some reason cannot bring themselves to admit that their reasoning even involves assumptions! As if "assumption" is a dirty word, most odd, but anyway, back to the science...

Cosmology is another superb example, the claim that the laws of nature billions of years ago were identical to the laws we discern today is an assumption, the claim that the laws of nature 13 billion light years away are the same as they are locally is an assumption.

The cosmologist readily admits this too, then again theoretical physicists are notoriously rigorous in their logic, no muddling about in that field, no irrational dread of assumptions there.

[Jose Fly]

[Replying to dad1 in post #19]

This is all true, and far from controversial except to a few individuals I sometimes encounter who for some reason cannot bring themselves to admit that their reasoning even involves assumptions! As if "assumption" is a dirty word, most odd, but anyway, back to the science...

Cosmology is another superb example, the claim that the laws of nature billions of years ago were identical to the laws we discern today is an assumption, the claim that the laws of nature 13 billion light years away are the same as they are locally is an assumption.

The cosmologist readily admits this too, then again theoretical physicists are notoriously rigorous in their logic, no muddling about in that field, no irrational dread of assumptions there.

Again you make it seem as if scientists sit around a table and just assume things out of thin air and do nothing else. I've explained to you many times, including in this thread, how scientists go out of their way to test their assumptions.

Yet it doesn't seem to have sunken in with you, which is both strange and fascinating to behold.

[Sherlock Holmes]

[Replying to Jose Fly in post #22]

That's rather amusing, the fact that one cannot test any assumption without first making other assumptions seems to have escaped you!

[Jose Fly]

[Replying to Jose Fly in post #22]

That's rather amusing, the fact that one cannot test an assumption without making other assumptions seems to have escaped you!

Yes, as we covered many times we do assume that things in the past weren't magically radically different. We assume gravity existed, the earth was spherical and orbited the sun, organisms had DNA, etc.

IOW, we don't embrace solipsism as so many creationists do.

[Sherlock Holmes]

[Replying to Jose Fly in post #22]

That's rather amusing, the fact that one cannot test an assumption without making other assumptions seems to have escaped you!

Yes, as we covered many times we do assume that things in the past weren't magically radically different. We assume gravity existed, the earth was spherical and orbited the sun, organisms had DNA, etc.

IOW, we don't embrace solipsism as so many creationists do.

I frankly don't care what it is that any scientist assumes, only that they understand and admit what it is they have assumed.

[Difflugia]

for all we know it changes slowly according to some as-yet undiscovered law, we don't know so we assume.

At absolute best, that's an overstatement. We have a number of different measures of time with which we can calibrate rates of radioactive decay. If radioactive decay rates have changed, then not only would multiple mechanisms of radioactive decay have to have changed in exact proportion with each other, but such disparate other measures as rates of fluvial deposition, the annual nature of tree rings, and seasonal variations in coral growth. One could perhaps posit mechanisms that somehow affected all of these in a way so subtle and deceptive that it's gone unnoticed, but in light of the Occam's Razor thread, I'd suggest that such suggestions lack merit.

What we can definitely say is that at no time in history have rates of radioactive decay changed relative to other measurable rates of change. It is certainly possible (in the philosophical, apologetic sense) that every measurable, historical rate of change has altered in an exactly proportional way, but in a practical sense, that's hardly worth considering.

[Sherlock Holmes]

for all we know it changes slowly according to some as-yet undiscovered law, we don't know so we assume.

At absolute best, that's an overstatement. We have a number of different measures of time with which we can calibrate rates of radioactive decay. If radioactive decay rates have changed, then not only would multiple mechanisms of radioactive decay have to have changed in exact proportion with each other, but such disparate other measures as rates of fluvial deposition, the annual nature of tree rings, and seasonal variations in coral growth. One could perhaps posit mechanisms that somehow affected all of these in a way so subtle and deceptive that it's gone unnoticed, but in light of the Occam's Razor thread, I'd suggest that such suggestions lack merit.

What we can definitely say is that at no time in history have rates of radioactive decay changed relative to other measurable rates of change. It is certainly possible (in the philosophical, apologetic sense) that every measurable, historical rate of change has altered in an exactly proportional way, but in a practical sense, that's hardly worth considering.

You mean as if there might be a universal law of nature that influences all radioactive decay in such a way that observation of their relative values alone masks that law? - yes I see what you mean!

[DrNoGods]

[Replying to Sherlock Holmes in post #21]

This is all true, and far from controversial except to a few individuals I sometimes encounter who for some reason cannot bring themselves to admit that their reasoning even involves assumptions! As if "assumption" is a dirty word, most odd, but anyway, back to the science...

Who has argued that there is anything wrong with assumptions, or denying that they exist? I haven't seen anyone do that here. Assumptions are often necessary to address a problem or arrive at a best explanation, and anyone can try to show that an assumption is invalid in a science effort. But if the assumption is based on legitimate observations and reasoning, then it is valid to adopt it until it is shown to be wrong.

Constant radioactive decay rates over time is a reasonable assumption given what we know about how the process works and how atoms are constructed, and from a tremendous number of measurements and theoretical studies.

We can measure the emission spectra of distant stars and see that they are made of the same basic constituents as our own star. The hydrogen emission spectrum from a distance star may be red shifted, but it contains the same characteristic spectral lines as hydrogen on Earth or the sun when in similar excitation states. From this we can conclude that the hydrogen atoms at the distant star are the same as the hydrogen atoms much closer to us.

We know the energy level distribution of the hydrogen atom which determines the wavelengths of the emission lines, and if this were different at the distant star we'd see a different emission spectrum, but we don't. Ditto for He and other elements. We don't have to visit the star to know this ... we have the photons that have travelled millions or billions of light years from the star to our telescopes and spectrometers that confirms that the atoms billions of light years away are the same as they are here, in any direction we look. This doesn't require an assumption, but it can be reasonably assumed that radioactive decay of those atoms would behave the same as the atoms much closer to us.

[Jose Fly]

I frankly don't care what it is that any scientist assumes, only that they understand and admit what it is they have assumed.

And to you, admitting that we assume the earth still orbited the sun in the past is some sort of revelation? Something scientists have been concealing?

[Sherlock Holmes]

[Replying to Jose Fly in post #29]

Allow me to help you with this. The claim that the Earth orbits the Sun (or more precisely their barycenter) is most certainly not an assumption, it follows directly from other assumptions. I can't imagine why you think someone has been concealing this from you, there are many good books that will explain it in fair detail.

An Introduction to Celestial Mechanics.