On 20/11/12 16:55, Martin Brown wrote:
> On 20/11/2012 16:19, Yousuf Khan wrote:
>> Most of what is taught in high school physics today is stuff discovered
>> from 400 years ago, as discovered by Isaac Newton. I understand the need
>> to keep things simple for HS students to digest, and most of the physics
>> from 400 years ago is still basically the only stuff that we deal with
>> in everyday life. However, when modern physics is introduced in
>
> Which makes it a great foundation on which to build further knowledge
> and it is still relevant to the rest of the population in daily life.
>
> People still drive too close and fast like they do not believe in basic
> Newtonian physics such as momentum and kinetic energy.
>
>> university, a lot of students are surprised by how different physics is
>> at these extreme levels. Many are unable to grasp it and end up becoming
>> deniers about Quantum Mechanics, and especially Relativity.
>
> Not sure that the physics and chemistry graduates are the problem here.
>
> Most of the deniers study soft subjects or electrical engineering where
> relativity must be lamentably taught based on the number of nutters who
> still write in to Wireless World (it was much worse in the 1970's).
I don't know how anyone can "still write to Wireless World" as no
magazine of that title has existed since 1984.
I do recall the excellent series of articles in that magazine by the
distinguished physicist Dr Scott Murray called "A heretics guide to
physics" where he demonstrates how physics has slid into the realm of
mysticism.
>>
>> With modern computer graphics equipment, it should be easier than ever
>> to visualize modern physics without going into explicit details about
>> its complex equations. Maybe it's about time that modern physics is
>> introduced into high schools, at a basic level, mainly to get them used
>> to the far out ideas that are beyond our everyday experiences, and
>> prevent more from becoming deniers? Relativity could be introduced into
>> the end of physics (mechanics) courses, while Quantum Mechanics could be
>> introduced into the end of chemistry courses? It shouldn't be a full
>> curriculum on these subjects, with experiments, etc., just a documentary
>> just to introduce them to the ideas that are modern physics.
>>
>> Yousuf Khan
>
> I disagree. Until you have a basic understanding of classical physics
> introducing relativity and quantum mechanics without the mathematics
> makes it into another just so story and prone to attack by deniers.
>
> The thing that really needs to be communicated is that at relativistic
> speeds common sense Galilean dynamics no longer works reliably.
But the speed of light is only about 1ft per nanosecond. Feet and
nanoseconds are both everyday unit in this century. What is missing is
any explanation of why dimensions change other than because the maths
demand it to make the second postulate true.
Beckmann and Mandics pointed out the possibility that Lorentz transforms
could simply be equivalence formula, making up for inaccurate
electrodynamics by suitable deforming space and time to achieve the
correct result. Thus cries of "relativity works" in no way proves that
it is correctly based.
Essen makes the same point a different way:
"Science involves measurement and measurement requires a system of units
which need to be carefully chosen such that do not have duplication.
Consider now the simplest of all measurements, the measurement of
velocity v expressed as the distance d travelled in time t. The result
is expressed as v=d/t. It is possible to define units in any two of the
quantities in this expression. In practice the units of distance and
time are defined and velocity is measured in terms of those units. If
the unit of velocity were defined as well then the value v can be
expressed in two ways in terms of the unit of velocity and in terms of
units of length and time. Conflicting results could be obtained.
Only a unit of measurement can be made constant by definition.
Making the velocity of light have a constant value c even to observers
in relative motion is comparable to making a unit of measurement
duplicating the units already defined. The definition of the unit of
length or that of time must be abandoned. To meet Einstein's two
conditions it is convenient to abandon both.
The contraction of length and the dilation of time can now
be understood as representing the changes that have to be made
to make the results of measurement consistent. There is no
question here of a physical theory but simply of a new system
of units in which c is constant, and length and time do not
have constant units but have units that vary with v^2/c^2. Thus
they are no longer independent, and space and time are
intermixed by definition and not as a result of some peculiar
property of nature.... If the theory of relativity is regarded
simply as a new system of units it can be made consistent but
it serves no useful purpose" Essen