Replies

I know because I've had to relearn some theories since I taught this class 25 years ago, but the facts are the same. For example, the universe has doubled in age since I was a boy,which gives you an idea of just how old I am.

That's a really strange quote, and a fairly worthless one. I wouldn't repeat it. It starts off OK, but then when the author goes to give an example of a theory that has changed, he says, "the age of the universe has doubled".

"The age of the universe" is not a theory. It is a fact: it is a physical property of the universe that we measure. It may be possible to derive a prediction of the age of the universe from a theory, but that's not what is done: we calculate it from a series of physical measurements.

"But in order to calculate, you need a theory!" you say. Perhaps, but those aspects of the theory (e.g. how light propagates through the universe, and how stars and supernovae work) haven't changed very much, while the measurements and measurement techniques have. The age of the universe is no more a theory than the length of your foot is a theory.

If anything, his example stands as a counterexample of his assertion that facts remain the same.

Now, you may argue that the "fact" is the true age of the universe, and that that hasn't changed (much), even if our measurement has changed. But when it comes to physical properties, measurements are all science ever has to work with. And yes, they change.

"The age of the universe is no more a theory than the length of your foot is a theory."

When you observe a car driving down the road at speed of 30 mph for and 1/8 of a mile, of coarse you know exactly how long the car has been driving for because:

You can know for sure exactly where that car started. It surely started in a town 30 miles away. That is of coarse not an assumption.

You certainly know for sure that the car has been traveling a constant speed for its entire life, nothing could change that. (and absolutely sure constant for 4 billion years)

So you know for sure that that the car trip, after observing the car for 1/8 of a mile has, has been traveling exactly 1 hour to 5 significant digits. Of coarse there are no assumptions in this. This is a measurement and "this is no more a theory than the length of your foot is a theory".

Of coarse you know with absolute certainty how much radioactive or daughter substance was present at the start, or where x started. Your invention of the very first time machine for going backwards in time to observe x is quite remarkable, the first of its kind, you should patent it.

Of coarse you know that the rate of decomposition, or the speed x, the always remained constant, and has certainly remained absolutely constant to 5 significant digits for exactly 4 billion years to 10 significant digits, this is
"this is no more a theory than the length of your foot is a theory".

Pardon the sarcasm, but you are making assumptions and calling it "no more a theory than the length of your foot is a theory".

Time is the escape hatch of your chance + enough time worldview, and given enough you time you believe that the absurdly improbable can certainly happen....just give it enough time. Be careful that you don't drown in your all- knowing assumptions, as your escape hatch may not be as open as you believe.

I can't argue astronomy. I'm not an astronomer. But I do know words and words mean things. This college professor, who has been teaching for a number of years, quote about theories is accurate. Theories can, and do, change. However, there are many scientists today who would like you to believe that theories are laws. They are not.

I take it you are not an astronomer yourself so your astronomical opinions are about like mine-next to meaningless. (Since you've labeled yourself "Physicist" you actually may have more knowledge about astronomy than my two semesters in it. But I digress.) I would suggest what you find wrong with this author is his statement that theories can change-not his views on astronomy. Astronomers better than anyone knows how frequently theories changes and, at least, are up front about that.