The strongest arguments prove nothing so long as the conclusions are not verified by experience. Roger
Science is built up with facts, as a house is with stones. But
a collection of facts is no more a science than
a heap of stones is a house. Henri
At the heart of science is an essential balance between two seemingly contradictory attitudes;
an openness to new ideas (no matter how bizarre or counterintuitive they may be)
and the most ruthless skeptical scrutiny of all ideas, old and new.
This is how deep truths are winnowed from deep nonsense. Carl Sagan (1934-1996)
A scientific body of knowledge is called a theory.
What makes a theory scientific is that it makes definite
predictions which can be disproved experimentally.
The Scientific Method is a process which allows
theoretical knowledge to evolve under experimental constraints.
A physical theory is not an explanation.
It is a system of mathematical propositions, deduced from a small number of principles,
which aim to represent as simply, as completely,
and as exactly as possible a set of experimental laws.
Pierre Dûhem (1861-1916)
On the laws of Nature
Will the law of gravity always remain confined to a theory ?
Nothing can be stated clearly unless proper meanings are assigned to
crucial words like theory and law
in a scientific context.
In particular, the word "theory" is not an insult
(as in the silly saying "it's just a theory").
A theory is simply a consistent
body of scientific knowledge not yet disproved by experiment
(at a given level of precision).
In experimental sciences, a theory can never be
proved for certain;
it can either be disproved by experiment or be consistent
This is precisely was makes a theory scientific.
A statement that can't possibly be disproved by experiment may be highly
but it does no belong in an experimental science...
It might be mathematics, philosophy or religion, but it's not physics.
Now that we have the basic vocabulary straight,
we may discuss the example of gravitation.
Gravity is a physical phenomenon which is obvious all around us.
As such, it's begging for a scientific theory
to describe it accurately and consistently.
A law is a rule within a theory
(like Newtonian mechanics).
Newton's own inverse square law of Universal gravitation
describes gravity extremely well
in terms of Newtonian mechanical forces. Loosely stated:
Two things always attract each other in direct proportion of their masses
and inversely as the square of the distance between them.
We do know that the Newtonian theory does not provide the ultimate law for gravity.
General Relativity (GR) provides more accurate
experimental predictions in extreme conditions
(e.g., a residual discrepancy in the motion of the perihelion of Mercury
is not explained by Newtonian theory but is accounted for by GR).
Does this mean Newton's theory is wrong ? Of course not.
Until we have a "Theory of Everything" (if such a thing exists)
any physical theory only has a limited range of validity,
where its predictions are accurate at a stated level of precision
(stating the claimed precision is very important in Science;
an experimental prediction is meaningless without it).
The Newtonian theory predicts the motion of planets
in the Solar System to many decimal places, over eons...
That's all we ask of it and that's what makes it so valuable.
Even General Relativity is certainly not
the ultimate theory of gravitation.
We know that much because GR is a classical theory,
as opposed to a quantum theory
(i.e., a theory obeying quantum logic).
So, GR is not mathematically compatible with quantum phenomena
which are so obvious at a small scale.
Science is just a succession of better and better approximations.
This is what makes it nice and exciting.
If we insisted at all times on "the whole truth and nothing but the truth"
no meaningful scientific statement could ever be made.
As a consistent body of knowledge,
each theory allows you to make such statements freely,
knowing simply that the validity of your discourse is only restricted
by the general conditions of applicability of that theory.
a framework, scientific discourse would be crippled into utter uselessness.
(2007-07-14) Controlled Experiments (Francis Bacon, 1590)
It's easier to isolate the causes of a phenomenon when we create them.
Experiments are now so intertwined with Science that we may forget
that good Science can be performed without experiments.
There are no experiments in Astronomy.
Astronomers have to be content with observing phenomena over which
they have no control.
The same can be true, albeit less systematically, of other sciences as
well. There was a time when particle physicists relied on
random cosmic rays of unknown origin for something worth observing.
Similarly, experiments in evolutionary biology can only be performed
on simple lifeforms that reproduce so rapidly that a large number
of generations can be observed in a reasonable amount of time.
The power of natural selection established under such controlled
conditions can be extrapolated to more complex lifeforms with longer lifetimes
just like physical laws established in the laboratory are
extrapolated to astronomical objects.
Paradoxically, the aim of Science is to provide ways to
dispense with countless experiments.
it is now pointless to play with objects like
magnets in the hope
of producing perpertual motion when we
have established to a fabulous degree of precision
that all the simple components of such
systems obey conservation laws that preclude it
(including relativistic mechanics,
Scientific advances come from discovering new aspects of reality
(e.g., radioactivity in 1896)
new paradigms (e.g., quantum logic)
or clever ways to harness nature (modern technology).
From a pedagogical standpoint, it's useful to repeat simple-minded
experiments to stress the fact that Science is ultimately based on
observation, not dogma.
Of course, no one will ever be able to actually repeat all
the experiments on which basic scientific knowledge is based, but we should
at least be satisfied that we
could reproduce any key experiment we like.
Occasionally, a pedagogical demonstration turns into a flop
which the teacher may or may not explain correctly...
Watch carefully the videos quoted in the footnote below, where
Julius Sumner Miller
makes the following statements pertaining to the time it takes for
things to roll down an inclined plane, starting from rest:
All hoops roll alike (hollow cylinders).
All disks roll alike (homogeneous cylinders). They beat all hoops.
All spheres roll alike (homogeneous spheres). They beat all disks.
He then proceeds to demonstrate this on a wooden inclined plane.
In some cases, he fails miserably but allows the showmanship to prevail
over his scientific training, using apologetic sentences like:
"It will be a little difficult to check this."
"If our provisions for Nature were of an adequate sort, I could show you
the following phenomena..."
"We have a little trouble with this board, but that's another piece of evidence
that, when you deal with Nature, you must meet Her requirements...
A little difficult to show it (the hazards of experiments)
but I'm going to tell you: All spheres beat all disks."
Can you discover the fallacy that Julius Sumner Miller chose to ignore?
Julius Sumner Miller - Physics - Rolling Things
Part 1 |
(2007-07-15) History of the Scientific Method
The key ideas behind modern science.
Mathematics serves as the language of all natural sciences, but it's not itself
a natural science.
That year, an academic competition was created in pre-revolutionary France
which is still in existence:
Every year, selected graduating high-school students compete in what's called the
général (short for Concours général des
lycées et collèges).
Concours Général of 1973 :
At the age of 17, I had the honor to represent my school in mathematics and philosophy
(I was coached after hours by my philosophy teacher,
Against some expectations, I didn't do very well in mathematics but I nailed
it in philosophy and made the front page of the local paper
(although I didn't win the top prize;
two other people, somewhere in France, were ranked
ahead of me). The question we were asked was:
In what sense can we distinguish between true and false sciences ?
Thus, even at that young age, I must have known already... I must have known
that there ought to be more to Science than scientific appearances !
As Science progresses, the time it takes for anyone to obtain a working
knowledge of the state-of-the-art in any field keeps increasing but,
arguably, motivated teenagers can still get a fairly good grasp of what
distinguishes good science and pseudoscience.
Yet, adults and trained scientists may go astray...
It's probably uncharitable to expose people who are trying to make a scientific
contribution without the benefit of a proper scientific education.
it seems next to impossible to provide some wannabe-scientists with the elements
that would make them wise critics of their own theories.
Even at my own modest level of notoriety, I am regularly confronted with that nagging
problem. A few gurus and luminaries chose a humorous approach to the issue:
On the other hand, some trained scientists who make outrageous claims
may fool everybody except their better peers.
They can even fool themselves
If they don't fool themselves, they are simply liars or
crooks and things are easier to sort out!
(2011-10-22) Faster-than-light neutrinos?
Not ready for prime time.
Scientific investigation goes on in spite of distorted media reports.
In a CERN press release dated
(which has been corrected and updated several times since)
it was originally announced that the OPERA team at Grand-Sasso was reporting
the detection of neutrinos traveling faster than light,
as part of a experiment conducting jointly with CERN.
This careless release (whose original content went against the very
core of modern physics)
started a media circus to which virtually all scientists with
a modicum of media visibility had to reply while the error was
being corrected. Eventually, at least two OPERA leaders lost their jobs.