Subject:
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Re: sensors, actuators, and software, oh my!
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 4 Apr 2003 05:50:16 GMT
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Original-From:
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Jim Choate <ravage@+StopSpam+einstein.ssz.com>
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Viewed:
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922 times
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On Thu, 3 Apr 2003, Steve Baker wrote:
> Dan Novy wrote:
> > Up for discussion.
> >
> > So, while discussing "the next big project," my ten year old and I
> > tried to come up with a complete list of all the possible "signals"
> > available at any one time that could be incorporated into a robot,
> > whether practical, or useful or not. Questions like, "Does gravity
> > count as a signal? It's "on" all the time, can be used to create motion,
> > etc. There are standard signals or influencers (?) like light,
> > temperature, atmospheric pressure, radio signals, tv signals, any RF
> > stuff, etc. We were interested in what other people thought.
> > So, the question is, standing in a room, or in an open field, how
> > many signals/influence fields are passing through you at any one time,
> > ready to be sampled?
A: How many detectors do you have and what are their transfer functions?
The reality is that it is the number of -observers- which matters.
> One...or maybe infinity.
>
> Most modern physicists believe that matter and energy are the same
> thing - and that all forces can be described by some (as yet
> undiscovered) "Unified Field Theory".
No, they are not the same thing, they can be converted into each other
according to a well described function.
> In that sense, there is one unified field that is EVERYTHING in the
> universe.
Pantheism will be found to be the one true religion!
> If you approach it from the other direction, all radio, light, X-rays,
> Cell-phone signals, Cosmic rays, etc are Electromagnetic waves - and
> those can (in principle) exist at all frequences from the very longest
> to the very highest.
Actually not. There is a limit on the highest frequency related to the
Plank scale. You can only get so small and then the concept of distance
gets rather modular (not to mention that as the frequency goes up so does
the energy per photon, which is limited by E=mc^2). With regard to the
longest, it is limited by the size/age of the universe and the speed of c.
Then you've got the expansion effect which over time lowers all
frequencies in relation to the size of the cosmos.
> Gravity is a different force - and since it's waves are not really
> detectably right now, it doesn't appear as anything other than a force
> in a direction - without a 'frequency'.
Gravity is the interaction of matter and space (I really don't think of it
as a force like the others but more an effect) and has no 'intermediate
vector boson' per se. So it is actually likely that thinking of 'gravity'
and 'frequency' is just confused.
> Then, there are the 'weak' and 'strong' nuclear forces - which is what is
> really acting to keep matter doing what it does - so in a sense, those
> are what is behind sound, air pressure, water pressure, wind, water
> waves and large steel hammers!
??? The majority of these forces are E-M in nature and have little to do
with inter-atomic forces (ala weak and strong), see Van DerWaals Force and
Adhesion for examples. The first thing that hits when two atoms come
together is the electron shells. Since the force is related to the square
of the distance, as two atoms get close together the forces between
electrons get really!!! big (the math is really easy, you need a pocket
calculator). Conversely, if one shell is short (ie has a 'hole') and the
other has an extra electron (ie has a 'doner') then they can 'share' the
electron and this creates attractive electro-static (there is no current
flow so the results must be static) forces. Alternatively, if both have
extra electrons then they'd repel very strongly.
> What we see as atoms pressing against
> other atoms to make these effects can also be looked at as wave
> probability functions (Electrons, Protons, etc) being acted upon
> by fields - gravity, etc. When a "solid" object hits another one,
> the forces that stop them merely swooshing straight through each
> other are the 'weak' and 'strong' nuclear forces.
"I feel that it is a delusion to think of the electrons and the fields as
two physically different, independent entities. Since neither can exist
without the other, there is only -one- reality to be described, which
happens to have two different aspects; and the theory ought to recognize
this from the start instead of doing things twice."
Albert Einstein
"In atomic theory we have fields and we have particles. The fields and the
particles are not two different things. They are two ways of describing
the same thing - two different points of view."
P.A.M. Dirac
The reality is that 'solid objects' aren't. At this scale -everything- is
a strangely shaped bag of atoms bouncing around.
> You can extend what you mean by "light" as a separate signal until
> you have to admit that in truth, radio waves are just very low
> frequency light
Actually -anything- that is propogated by a photon (irrespective of
frequency) -is- light.
Holding a bar magnet in ones hand and shaking it is a very low energy
light for example.
> why physicists talk about "Electromagnetic Waves" to cover all of
> those phenomena that we humans percieve as different.
See "Quantum Electro-Dynamics" (QED) for a start.
> Then, you look at "clearly" different forces - like the ones
> that hold molecules together
ala Weak and Strong.
- and that keep atoms from falling
> apart - and those too can be described mathematically with the
> same equations as the electromagnetic waves.
The equations have the same form (as compared to 'same equations'), and at
high enough energy levels the results merge into a single effect described
by a single equation set (one can think of it as two objects melting and
mixing, but that is a lame comparison at best).
Some good 'intro' books I can offer (you need college level calc and
physics):
The Structure and Interpretation of Quantum Mechanics
R.I.G. Hughes
ISBN 0-676-84392-4
The Nature of Space and Time
Stephen Hawking, Roger Penrose
ISBN 0-691-05084-8
Collective Electrodynamics: Quantum Foundations of Electromagnetism
C.A. Mead
ISBN 0-262-63260-8
--
____________________________________________________________________
We are all interested in the future for that is where you and I
are going to spend the rest of our lives.
Criswell, "Plan 9 from Outer Space"
ravage@ssz.com jchoate@open-forge.org
www.ssz.com www.open-forge.org
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Message has 1 Reply:
 | | Re: sensors, actuators, and software, oh my!
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| (...) More than 3, which is the number of sensor inputs on a Mindstorms brick. :-) (...) I see that you adopt the modern relativist view . I agree to the extent that it depends on the number of RCX bricks present because they only have three sensor (...) (21 years ago, 14-Apr-03, to lugnet.robotics)
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Message is in Reply To:
| | Re: sensors, actuators, and software, oh my!
|
| (...) One...or maybe infinity. Most modern physicists believe that matter and energy are the same thing - and that all forces can be described by some (as yet undiscovered) "Unified Field Theory". In that sense, there is one unified field that is (...) (21 years ago, 4-Apr-03, to lugnet.robotics)
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