Re: What are physicists trying to do?
- From: "Martin Hogbin" <goatREMOVETHIS123@xxxxxxxxxx>
- Date: Thu, 3 Jan 2008 20:01:23 -0000
"GSS" <gurcharn_sandhu@xxxxxxxxx> wrote in message
news:1dbfb2b6-1dd3-4b15-8870-158f7fa0c0a4@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Jan 2, 11:47 pm, "Martin Hogbin" <goatREMOVETHIS...@xxxxxxxxxx>
wrote:
"GSS" <gurcharn_san...@xxxxxxxxx> wrote in message
Do you mean that it is 'naive, illogical and unhelpful' even to expect
that a physical theory must provide a cause and effect type linkage
between physical entities?
'Cause and effect' sounds a simple enough concept but when
considered more carefully the distinction becomes less clear.
We have yet to agree on what 'physical' entities are.
Physical concepts and entities are those that can be quantified,
That is a good start.
that
can be assigned some (combination) physical dimensions,
What are 'physical dimensions'?
that can be
measured in physical units.
I suppose 'physical units' are defined as units that measure
physical quantities?
This is how NIST defines a physical quantity -
'A physical quantity is a quantity that can be used in the mathematical
equations of science and technology'.
Kindly explain how such an expectation
could ever be considered illogical?
First we must agree on what a 'physical entity' is and how
one can tell cause from effect.
Cause precedes effect.
I will go with that, but what is a 'physical entity'.
This is the problem, you have a very sharp distinction between
what you would call physical and what you would describe as
abstract. You are insisting that everything in nature or the human
imagination must fit into one of these categories.
Which of these physically exists?
Mass
Energy
Power
Entropy
I am interested to know which of these you consider physical. What
about charge and temperature?
All of the above have assigned physical dimensions and hence belong to
physical concepts, entities and parameters.
What are the dimensions of temperature?
Your distinction is based on your personal experience
where everything fits neatly into the physical and abstract
categories. Chairs are physical; beauty is abstract.
I hope you are familiar with the notion of 'physical dimensions' and
the 'dimensional analysis'.
Are you going to restrict us the dimensions to length, mass, and time,
or is charge, for example, allowed?
All entities, parameters or quantities to
which some 'physical dimension' can be assigned and which can be
measured in specified units, can be broadly classified as physical
entities, parameters or quantities.
So, if it can be measured it is physical? I would accept that. Or
do you want to place more restraints on what is physical?
What are 'physical concepts'?
If you deliberately choose not to make any distinction between
physical concepts and abstract mathematical notions then it is too bad
for physics in general and for physicists in particular.
How can I tell which is which?
For example, when you regard the notion of probability waves as a
physical concept, you are damaging the physics!
You mean you do not like this concept because it is not like
anything else we know.
No, because it is a mathematical concept. It does not possess any
physical dimensions and it cannot be measured in 'physical units'.
What about the electric field then. Is that physical?
When you regard the metric tensor of spacetime or any other higher
dimensional abstract space as a physical quantity, you are again
degrading the physics!!
Why?
Because firstly you are treating an abstract entity as a physical one...
I am still not clear how you define the difference.
and secondly you are asserting that a physical entity (mass) could
somehow (magically) influence an abstract entity (spacetime metric).
Give me an example of something influence that is not 'magical'.
I cannot understand what you mean .When you regard the dimensions [L] = [T] or G = c = 1, you are
again undermining the physics!!!
Are you just talking about a choice of units of measure here?
No, I am talking about floundering of physical dimensions here.
Once again we are back to what is physical and what is not. How
would you define 'physical'?
As stated above, all entities, parameters or quantities to which some
'physical dimension' can be assigned and which can be measured in
specified units, can be broadly classified as physical entities,
parameters or quantities.
I cannot understand what you mean here. Can you give me some examples.
You could start with the quantities I give above. Please add any others that
you consider make the distinction clear.
Are you happy with Newtonian physics?
Are Newton's laws of motion and gravitation good 'physical'
physics in your opinion?
Yes, in comparison with the Relativity physics, I am happy with
Newtonian physics.
So Newton's laws of motion are good 'physical' physics?
Newton's laws do deal with physical concepts and entities. The notion
of 'action at a distance' was the major weakness in the Newtonian
gravitation...
Why?
Because it implied a lack of any physical mechanism of gravitational
interaction.
So gravity is not 'physical'?
...which needed to be resolved in the beginning of 20th
century. But in the grand maze of the unknown, relativity lead us in
wrong direction of 'spacetime' geometry.
What alternative would you propose?
It is well known that the 'field influence' of a charged particle
spreads out in its radial direction at the speed of light. Though
ordinary matter is electrically neutral in the 'bulk', yet it consists
of a finite spatial distribution of positive and negative charges.
This spatial distribution of charges ensures that their radial fields
don't completely cancel out but give rise to a sort of 'residual
ripple' field which may be identified with the gravitational field of
ordinary matter.
Now you are just making it up as you go along.
Therefore, this 'residual ripple' field influence or
the gravitational field will also propagate radially at speed of
light. I believe a quantitative model on these lines could have been
developed in 20th century had GR not lead us in the wrong direction of
'spacetime geometry'.
This is pure speculation, what evidence to you have? Relativity
is based on experiment.
We do not seem to be getting anywhere. You insist on some
distinction between measurable quantities which makes
some physical and some not.
Perhaps you could humour me for a moment. Suppose that
we assume that the _only_ reality is that we can personally
observe. The feel of your hand on a table or the observation that
a meter reads '55'. Nothing else is to be taken to be 'real'.
--
Martin Hogbin
.
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