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Luke Conlin
1
There is a growing emphasis on learning through ‗inquiry‘; i.e. authentic scientific practices (NRC 1996)
UMD perg ‗defines‘ science as the pursuit of causal mechanisms
Mechanism has been underemphasized in science education
It has been possible to succeed through college science while holding wildly wrong conceptual ideas
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―…the reason why physics has ceased
to look for causes is that, in fact, there
are no such things. The law of
causality…is a relic of a bygone age,
surviving, like the monarchy, only
because it is erroneously supposed to
do no harm.‖ (Russell, 1913)
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5
First horn
EITHER causation places restrictions on factual content
of science…
We must find some factual restriction that can be applied
across all sciences…
Second horn
OR it does not
causation is an empty honorific
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DirectlyThrough
mathematical conditions
Indirectly
Through warrants for
applying solutions
Semantically
Through rules that constrain the physical
model
Tool for solving biggest theoretical
problems
Generativity in finding new laws
Tool for applying theory empirically
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As enforced by mathematically expressible principles
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No input before output
No interaction via spacelike intervals
No action-at-a-distance
No backwards causation
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Evans, D. J., & Searles, D. J. (1996). Causality, response theory, and the second
law of thermodynamics. Physical Review E, 53(6), 5808-5815.
―Restricted by Principle of Causality: When physicists add the rule
that adjacent triangles must have a consistent notion of time—so that
cause and effect are unambiguously distinguished—the outcome is a
four-dimensional spacetime that looks tantalizingly like our universe.
(below)‖
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Jurkiewicz, J., Loll, R., Ambjorn, J., & Concepts, K. (2008). Using causality to
solve the puzzle of quantum space-time. Scientific American.
By providing warrant for throwing out spurious solutions
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You throw a rock into the air
at 10 m/s from 1 m above
the ground. How long will
it take to hit the ground?
00
2
2
2
2
1ytvgty
dt
ydmF
Answer #1:
2.1 seconds
Answer #2:
-.096 seconds
physically
unreasonable!
Banks, T. (1985). T C P, QUANTUM GRAVITY, THE COSMOLOGICAL CONSTANT AND ALL THAT... Nuclear Physics B, 249, 332–360.
Burke, W. L. (1970). Runaway solutions: remarks on the asymptotic theory of radiation damping. Physical Review A, 2(4), 1501–1505.
Goldberger, M. L., & Treiman, S. B. (1958). Decay of the pi meson. Physical Review, 110(5), 1178–1184.
Ishak, M., Chamandy, L., Neary, N., & Lake, K. (2001). Exact solutions with w modes. Physical Review D, 64(2), 24005.
Magueijo, J., Albrecht, A., Coulson, D., & Ferreira, P. (1996). Doppler peaks from active perturbations. Physical Review Letters, 76(15), 2617–2620.
Mason, J. K., Lund, A. C., & Schuh, C. A. (2006). Determining the activation energy and volume for the onset of plasticity during nanoindentation. Physical Review B, 73(5), 54102.
Neary, N., Ishak, M., & Lake, K. (2001). The Tolman VII solution, trapped null orbits and w-modes. Arxiv preprint gr-qc/0104002.
Simon, J. Z. (1990). Higher-derivative Lagrangians, nonlocality, problems, and solutions. Physical Review D, 41(12), 3720–3733.
Clapp, R. E. (1968). Enforcing causality in numerical solutions of Maxwell's equations. Proceedings of the IEEE, 56(3), 329-329.
Fowler, M., & Maki, K. (1967). Conditions for Bound States in a Superconductor with a Magnetic Impurity. Physical Review, 164(2), 484-488.
Peebles, G. H., & Clapp, R. E. (1968). Comments on" Enforcing causality in numerical solutions of Maxwell's equations. Proceedings of the IEEE, 56(8), 1365-1365.
Pi, T. W., Hong, I. H., Cheng, C. P., & Wertheim, G. K. (2000). Surface photoemission from Si (100) and inelastic electron mean-free-path in silicon. Journal of Electron Spectroscopy and Related Phenomena, 107(2), 163-176.
Wismer, M. G., & Ludwig, R. (1995). An explicit numerical time domain formulation to simulate pulsed pressure waves in viscous fluids exhibiting arbitrary frequency power law attenuation. Ultrasonics, Ferroelectrics and Frequency Control, IEEE Transactions on, 42(6), 1040-1049.
Worster, M. G. (2006). Solidification of an alloy from a cooled boundary. Journal of Fluid Mechanics Digital Archive, 167, 481-501.
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A ball of unit mass sits at rest on top of a dome. What happens?
Answer #1: Nothing.
r(t) = 0, for all T
Answer #2: It slides down the
side after an arbitrary time
T
r(t) = 0, for t ≤ T
r(t) = (1/144)(t-T)4 for t ≥ T
initial conditions:
1
0)0(
0)0(
m
r
r
2
2
dt
rdmF
2
2
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dt
rdr
initial conditions:
physically
unreasonable!
By constraining the directionality of the causal model & thus the
kinds of problems that can be solved with it.
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Load paper into the printer.
Load the printer with
paper.
Spray Windex onto the mirror.
Spray the mirror with Windex.
Feed bread to the
guests.
Feed the guests with
bread.
I riddled Capone
with bullets.
I riddled bullets into Capone.
I dripped water onto the floor.
I dripped the floor
with water.
I poured Pepsi into the glass.
I poured the glass
with Pepsi.
“A-Problems” “B-Problems”
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Field Equation
• field is foregrounded
• Changes the state of space
Equation of Motion
• particle is foregrounded
• Changes the trajectory of particle
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(Renn et al., 2007)
OP*(POTENTIAL)=SOURCE
Core Operator,
Entwurf Operator,
Ricci Tensor,
Einstein Tensor,
etc…
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First horn
EITHER causation places restrictions on factual content
of science…
We must find some factual restriction that can be applied
across all sciences…
Second horn
OR it does not
causation is an empty honorific
• Norton proposes energy as an example
Is there any such principle?
• Even conservation of energy is non-universal
I argue there is not • Either Norton
must provide a good example or concede
This requirement is too restrictive
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We know that in classical
physics vacua have no active
powers, yet we routinely
attribute to them
the ability to draw things in—to
suck.
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DirectlyThrough
mathematical conditions
Indirectly
Through warrants for
applying solutions
Semantically
Through rules that constrain the physical
model
Thanks to Lindley Darden & all of you in
PHIL 858m for hearing me out!
Thanks to Matthias Frisch, as well as the
UMD physics education research group for
helpful discussions
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Clapp, R. E. (1968). Enforcing causality in numerical solutions of Maxwell's equations. Proceedings of the IEEE, 56(3), 329-329.
Fowler, M., & Maki, K. (1967). Conditions for Bound States in a Superconductor with a Magnetic Impurity. Physical Review, 164(2), 484-488.
Peebles, G. H., & Clapp, R. E. (1968). Comments on" Enforcing causality in numerical solutions of Maxwell's equations. Proceedings of the IEEE, 56(8), 1365-1365.
Pi, T. W., Hong, I. H., Cheng, C. P., & Wertheim, G. K. (2000). Surface photoemission from Si (100) and inelastic electron mean-free-path in silicon. Journal of Electron Spectroscopy and Related Phenomena, 107(2), 163-176.
Renn, J., Janssen, M., Norton, J. D., Sauer, T., Stachel, J., Divarci, L., et al. (2007). The Genesis of General Relativity. The Genesis of General Relativity, in 4.
Russell, B. (1957). Mysticism and logic. Garden City, N.Y.: Doubleday. Wismer, M. G., & Ludwig, R. (1995). An explicit numerical time domain formulation to
simulate pulsedpressure waves in viscous fluids exhibiting arbitrary frequency powerlawattenuation. Ultrasonics, Ferroelectrics and Frequency Control, IEEE Transactions on, 42(6), 1040-1049.
Worster, M. G. (2006). Solidification of an alloy from a cooled boundary. Journal of Fluid Mechanics Digital Archive, 167, 481-501.