"Not sure why Uniformitarianism shouldn't be taught. Do we have any reason to assume that physical constants weren't the same in the past as they are today?"
First, MrHambre has confused uniformitariansm with actualism. As a matter of fact, uniformitarianism as defined by Lyell is no longer practiced by geologists and other scientists and, in reality, ***not*** what is being taught in textbooks. Uniformitarianism, as defined by Lyell, consists of four principles:
1. uniformity of law
2. uniformity of process (actualism)
3. uniformity of rate (gradualism)
4. uniformity of state (steady-statism)
Darwin's theory of evolution directly contradicts Charles Lyell's principle 4. In the Tenth edition of his "Principles" in 1866, Lyell began to waver in his support of principle number 4 and by 1872, in the 11th edition of "Principles", Lyell had completely abandoned it. Thus, by 1872, Lyell had ceased to be a strict " uniformitarianist" as he originally defined it and conceded that uniformitarianism, as originally defined by all 4 principles wasn't a workable concept.
Since then, the major fight has been over whether principle number 3, "uniformity of rate" (gradualism), as a valid principle. This discussion was and continues to be muddied by many people, including geologists, who have repeatedly confuse gradualism with uniformitarianism as originally defined by Lyell and also confuse actualism with gradualism. Episodic geologic processes, such as meteorite impacts, eruptions of flood basalts, periods of rapid sea floor spreading as during the Cretaceous, and so forth have shown principle of gradualism to be invalid. In fact, the recognition of mass extinctions within the geologic record refuted the application of principle no. 3, gradualism, to evolutionary processes, even before Lyell died. Charles Darwin didn't accept uniformitarianism, as strictly defined by Lyell, because Darwin disputed both uniformity of rate (no. 3) and uniformity of state (no. 4) as it applied to evolution. At this point in time, the vast majority of geologists only accept 1.) uniformity of law and 2.) uniformity of process (actualism) out of Lyell's four original principles of uniformitarianism. Given that conventional geologists have currently abandoned half of the principles of uniformitarianism as propose by Lyell, it is unscientific to claim that conventional geologists of being dogmatic supporters of uniformitarianism as originally defined by Lyell. (A fun book on this topic to read is "Catastrophism" by Richard Huggett.)
Thus, MrHambre's first sentence should read "Not sure why uniformity of law shouldn't be taught." Getting back to the question "Do we have any reason to assume that physical constants weren't the same in the past as they are today?"
Yes, we do. There is research, which has been done and published, to test whether various physical constants have remained the same over the last couple of billion years. One example of such research is:
Lamoreaux, S. K., and Torgerson, J. R., 2004, Neutron moderation in the Oklo natural reactor and the time variation of alpha. Physical Review D. vol 69, p. 121701)
In this paper, scientists directly tested whether or not a constant governing nuclear reactions had remained the same or not over the last two billion years. They found that that nuclear physics has ***not*** changed by more than one part in ten million over the last two billion years. In case of the speed of light, this research suggests that, at worst, it might have speeded up ever so slightly over this period of time instead of slowing down as Young Earth creationists repeatedly claim. Finally, this and other research demonstrated the claim that conventional scientists unquestionably assume and never test the validity of the concept of actualism to be completely wrong.
An article discussing various published studies by scientists investigating whether fundamental physical constants have changed with time is:
"Controversy over whether the fundamental constants of nature change with time has reignited. A new study is casting doubt on an earlier claim that a key constant varied as the Universe evolved."
A major published paper discussed in the above popular article is:
M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, Th. Udem, T. W. Hnsch, M. Abgrall, J. Grnert, I. Maksimovic, S. Bize, H. Marion, F. Pereira Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, 2003, New Limits on the Drift of Fundamental Constants from Laboratory Measurements. Physical Review Letters. vol. 92, no. 23, Article 230802.
"This is a good point, Bill. Being far from a geology expert, I understand that the "old" laws of uniformitarianism is not longer taught, but I always understood the "new" law of uni. as processes, constants, and mechanisms have stayed the same over time."
From what I have found in looking through the scientific literature, there isn't any officially recognzied or published "new law of uniformitarianism". The so-called "new law of uniformitarianism" is largely a "lay" version of the "old law" that has developed over time by the careless use of this term by writers of popular science articles, geologists, and paleontologists, who have carelessly confused uniformitarism with either actualism, gradualism, or some combination of both.
I might note there are limits to actualism, as if a person goes far enough back in time, i.e. Early Precambrian, uniformity of process, as in the case of plate tectonics (or lack there of) and volcanism, as evidenced by komatites, can't be guaranteed. At that point, a geologist has to rely on uniformity of law. However, in case of the Phanerozoic and Late to Middle Precambrian, actualism works quite well. In case of the very beginning of the Big Bang, even uniformity of law has its limitations. A person has to use one's judgement when applying principle of interpretations.
Again, for a good discussion of uniformitarism, actualism, gradualism, catastrophism, and so forth is found in "Catastrophism"by Richard Huggett. I don't agree with everything argued in this book, but he presents some very thoughtful discussions about these terms and the complexities of what they mean in the real world. In fact, he defines 8 possible ways to classify the "systems of history" that various geologists / biologists / and various types of creationists use in explaining the history of the Earth and Life.
Also, he argued that the true opposite of catastrophism isn't uniformitarism. Rather the true opposite of catastrophism is gradualism with:
1. gradulism = constant rate.
2. catastrophism = changing rate.
As argued by Huggett, the vast majority of, if not all, conventional geologists are actually catastrophists, because they accept changing rates for geological processes, which when fast enough at specific times and instances produce "catastrophes", although they might think they are uniformitarists.
He would also noted that a proponent of meteorite impacts as having caused mass extinctions would be an actualistic catastrophist, while a proponent of a Noah's Flood caused by divine intervention would be a nonactualistic catastrophist.
One point that comes across in his book, is that there so much sloppiness, varibility, and carelessness in how terms like catastrophism and uniformitarism are defined by various people that it might be better to abandon their use in discussing such matters as their use only confuses what is being discussed as different people have a different concept of what these terms mean.
"For instance, Walt Brown uses the viscosity of water to explain his hydroplates. However, how do we know the viscosity of water has remained constant throughout the ages?"
Actually, it would be possible to answer this question. The angle of repose of cross-bedding in water-laid sedimentary rocks is dependant, in part, on the viscosity of the fluid moving the grains and gravity. If either of these factors changed over the last two billion years, a person would be able to find well-defined changes in average angle of the cross-bedding within water-laid sedimentary rocks deposited over this period of time. Thus, if someone wanted, they can determine whether water viscosity or gravity changed during this period of time. In a graduate level sedimentology seminar, a friend of mine actually did this as his class project. By compiling data that can be found in the published literature on cross-bedded strata for a variety of periods, he was able to make a very strong case that the value of gravity hasn't changed in the last two billion years. Similarly, the lack of change that he found in the average angle of cross-bedding found in sedimentary rocks for the last two billion years, also is very strong evidence that the viscosity of water hasn't changed in the last two billion years.
Loudmouth also asked:
"How do we know that the mass of rocks has been constant throughout time,"
Again, sedimentary particles., i.e. sand and silt, are minature rocks. If the mass of rocks change, the mass of particles like sand, silt, gravel, and clay, should also change. The mass of a sedimentary particle is what determines how they are transported, the type of sedimentary structures formed, how sediments accumulate, the angle of cross-bedding, and so forth. Had the mass of rocks changed, there should have been some very dramatic changes in the types of sedimentary rocks formed, the sedimentary structures exhibited by them, the angle of cross-bedding, and so forth. Also, there would have been some dramatic changes in volcnaic processes and the types of volcanic rocks they formed. That sedimentary and volcanic rocks don't show the type and extent of changes that a change in rock mass would create, easily demonstrates significant changes in rock mass hasn't occurred. For example the lack of any detectable changes in the average angle of cross-bedding hasn't changed over the last two billion years also argues against the mass of rocks haven'y change.
Changing the value of something as significant as viscosity of water, mass of rocks, or gravity will effect how natural processes rearrange materials beneath and on the surface to the point there will be such detectable evidence of these changes having occurred in the rock record. If someone was creative enough, they very likely can devise some way of determining if many of the other properties that Loudmouth mentioned in message 62 have change with time or not.