Rene Descartes or Rene Des Cartes (1596-1650) was a philosopher and mathematician with a basically simple theory of the universe that many saw as in line with the emerging science of the time. He basically took mechanics and made it a complete theory of a determinate-law universe composed of only matter and pieces of moving matter pushing other pieces of matter, and its only energy being the motion property of matter. In 'The World' his Cartesian physics hypothesised a fluid matter ether vortex motion pushing the planets around the sun, and had other particle push theories for terrestrial gravity and for magnetism. For religious believers Descartes also allowed a second God-determined immaterial spiritual energy universe with no determinate-law connection to the material universe but only to the mind or soul of humans.
Descartes' basic ideas were perhaps best put in his Principia Philosophiae (Principles of Philosophy) published in 1644. Or you can read an English version of his Discourse..., in Google Books - Descartes.
His full physics theory in 'The World' was not published till 1664, after his death.
Descartes was primarily a logician who did much interesting work
in philosophy and mathematics. He used logic rather than experiment
in developing his new science, and his logic is maybe best known
for his 'most certain' proposition "I think, therefore I am". He might
perhaps logically have taken a Gilbert-like conclusion from that, that
the universe certainly contained thinking things and did not certainly
contain any non-thinking things. But perversely Descartes' certain-logic
went with the opposite conclusion - that most things in the universe are non-thinking in line with earlier Atomists, and
that only God and humans think. He posited a separate spiritual-mental
universe distinct from the physical universe, and excluded from science.
Of course this Dualist conclusion does seem to accord with common views
of a stone not thinking, if not with Descartes' own certainty-logic. 'I think'
seems to fit better with 'I observe' and with observers existing - and directly
from that with things to think upon or observe from, such as signals
existing. But 'I think' really gives less support to the view that
no-thinking no-signals solid objects exist, which perversely is the basis of
Descartes Cartesian physics theory making him perhaps a mere theoriser such as William Gilbert had railed against.
And his 'Cartesian' physics seems to rest on a very doubtful view of the human senses, taking touch as being the only certain sense as supposedly being unique in not requiring sensory signals. Of course touch may seem less certain for liquids and very uncertain for gasses. Gilbert and Newton took all proper experiment or experience as equally valid for science. Should the assumed sensitivities of any observer be allowed to determine the validity of alternative physics theories anyway ? The issue arises for Descartes' physics, but perhaps applies also to some modern physics theories effectively taking sight as the only sure sense and light the only sure signal ?
George Berkeley's 'to be is to be perceived' philosophy concluding that non-thinking things did not exist, was no great challenge to Descartes matter push physics and no help to Gilbert signal physics since Berkeley somehow additionally concluded that signals informing thinking did not exist either. Berkeley was chiefly concerned with some 'non-causal non-physical thinking', while Gilbert was chiefly concerned with the significance of basic 'causal physical thinking' or natural responses to natural signals as in magnetic attraction etcetera. And a Descartes physics keeping science out of spiritual-mental matters was less a problem to religion than a Gilbert science that looked like allowing science to explain all including the mental and spiritual. Descartes science was confined to the merely technological, leaving religion to lord over the more important human and spiritual arenas. His science also required humans to be unique in the universe, unlike Gilbert's, and so was more acceptable to the Catholic church then.
In his logic-derived material universe theory, Descartes saw objects as mechanical only and animals as mechanical clockwork robots, and the human body, senses and brain largely likewise - except that humans alone had soul/self-awareness like God. His mechanism for automatic reaction by animals (and the human body largely) to 'signals' was as to direct push forces - so light basically punches eye nerves. Descartes theory viewed all 'signals' (or Gilbert corporeal and non-corporeal 'effluvia' and Newton 'spirits emitted') as corporeal material particles that pushed sense organs mechanically and mechanically caused animal actions deterministically, so that animals reacted more as billiard balls to other billiard balls and less as thinking things or robots responding to information signals.
Descartes had an invisible-vortex-push theory for planetary motion, and for terrestrial gravity he had a separate theory of celestial-particles moving away from the centre of the earth and so displacing and sucking-down masses in their path. His magnetism 'effluvia' were also invisible material particles and physically pulled and pushed magnets, for which he had to postulate left and right handed corkscrew shaped particles working like corkscrews. Descartes' universe was a mechanical ('wind-up') clockwork robot universe, with energy only as the property of matter being in motion and nothing other than God and human souls being non-material. His material universe was all matter with no empty space and with no separate energy besides the kinetic motion energy of bodies. His 'no empty space' was in line with Aristotle and Huygens but opposed the experimental evidence offered by Gilbert, Newton and others who supported non-corporeal energies or 'spirits' also existing - separately from matter and being maybe not visible but detectable by experimental science.
To Descartes the essential properties of bodies were only the absolute requirements that they must occupy some space and no two bodies could occupy the same space at the same time, so that any body motion contact involved pushing other bodies from the space they occupied. Bodies were of different sizes or shapes, and their pushing motions explain all physical behaviour including gravity, electricity and magnetism. One body could not penetrate another body, though a larger body might contain spaces that a smaller body could enter as especially might a thin fluid. Mass was simply the measure of the size and pushability of bodies. He had no real explanation of how bodies could differ in shape and fluidity if no attraction-type forces were involved - and so also no real explanation of conjoined-bodies pulling each other. Gilbert and Newton correctly saw this theory as always requiring detectable effects like drag. So Gilbert concluded that magnetism cannot work by push since magnets showed no effect on air or on candle flames, and Newton concluded that space had no push ether or continuum since planet orbits show no significant slowing effect. Both supported space as being empty or non-material and allowed both corporeal matter bodies and non-corporeal force energy or 'spirit' bodies, and saw 'Mass' as a measure of objects gravity production and response.
Descartes' philosophical Logical Mechanical Universe science theory ideas influenced many and basically still do. He made a major contribution to philosophy, and his basic science theory ideas have been adopted perhaps wrongly by the majority of physicists to date. Descartes produced 'laws of motion' that read almost the same as Newton's, though his motion examples are often about bodies being pushed by unseen ethers more like Aristotlian motion. Newton published a disproof of the part of Descartes' 'dead-matter' theory that involved ether vortex motion pushing planets around, but seems not to have taken that as essential to it and electro-magnetic field theory based on a modified Descartes ether idea became accepted by most physicists until the Mitchelson-Morley experiment of 1887 indicated that either the ether did not exist or ether motion did not exist, which Einstein agreed, though his spacetime continuum was ether-like if not a full replacement.
There was much support for Descartes ether push physics even after chunks of his own theory were firmly disproved. Hence Russian mathematician Leonhard Euler (1707-1783) rejected the planet motion and Earth tide ideas of Descartes. But still Euler supported general Descartes ether push physics, as even in publishing a 'proof' of Descartes push-attraction ether corkscrew magnetism in 1744 - another piece of Descartes theory that was not long in being disproved. Euler was maybe just another example of great mathematics backing bad science - see www.math.dartmouth.edu/~euler/
Directly opposing William Gilbert, Rene Descartes believed in the certainty of rigorous logical reasoning though not merely mathematical reasoning, and that experience and experiment were of less certainty. He largely went with the Catholic Inquisition requirement for Galileo that his science be put as 'just ideas'. Descartes held that his was the best science possible, with logically imagined causation explaining the universe to the best extent possible though it might be impossible to establish the actual causes of phenomena like gravity. Hence on causation he states a neo-blackbox position in his Principles of Philosophy Part 3.CCIV ;
"That, touching the things which our senses do not perceive, it is sufficient to explain how they can be."
"I most freely concede this, and I have done all that was required, if the causes I have assigned are such that their effects accurately correspond to all the phenomena of nature, without determining whether it is by these or by others that they are actually produced. And it will be sufficient for use in life to know the causes thus imagined ...."
Hence Descartes himself was maybe less fully committed to his push-physics than most of the physicists who supported it. And of course other physicists were soon producing real evidence that solid objects are not solid but are largely empty space with some perhaps-solid particles. So a billiard ball pushing another billiard ball may well be largely space 'pushing' space - with at most a very few particles contacting. So must the transfer of momentum from all the particles of one ball, to all the particles of the other ball, involve action-at-a-distance and not involve push-contact ? If most apparent contact is not contact, then any push physics has a problem and maybe needs mechanical ethers or particle emissions - and proving their solidity may not really ever be possible ? Contact requires a zero distance that is not measurable and so not provable like finite distances. If Descartes' push physics rested on touch, and Einstein's on vision, then maybe Gilbert/Newton response attraction physics alone having observers and signals within the physics was also the least dependent on particular human senses ? Descartes' physics also included solid push ethers, though some other push-physics theories do not.
Wave theory involving motions of material media became a significant part of Descartes physics, but from Einstein's time waves not involving motions of material media were postulated and were incompatible with Descartes physics. And determinate-law energy or 'spirit' that is not the motion property of matter yet affects the motion of matter, as in Gilbert-Newton attraction-physics forces and in 'field' forces, was also incompatible with Descartes physics.
In Descartes push-physics all physics energy is matter motion, and all matter motion is energy including uniform motion. In Gilbert-Newton attraction-physics all energy is either signal motion which is uniform motion, or is signal response motion which is acceleration motion and signals can be non-corporeal. And while in any Descartes-style physics all energy is basically absolute, any signal-response physics allows of at least some energy being basically relative. Hence all signal emission necessarily involves some motion of material or energy signals from an emitter relative to some receiver or observer that may themselves be in motion, and all responses to such signals as act as physical forces are relative matter accelerations. In both of the two seemingly very different types of physics, energy is basically linked with motion but in basically different ways. There are of course other types of physics, as those that try to replace matter itself with energy often in the form of some wave motion of something basically undefined or with some 'wave motion of nothing' or unassociated energy. And it seems that waves of any specified quantal frequency do especially respond to other waves of that quantal frequency only, as in standing-wave interference. While some would take that as only a rare phenomenon of little significance with an almost infinite variety of different frequencies possible, others postulate it as being more fundamental. All these types of physics have energy motion issues including interaction motion issues. The main experimental science concerns have to be trying to determine the validity of similarities or differences in the mathematics and predictions needed by such different physics theories.
In classical Galileo-Descartes push physics, matter chiefly has the contact- push property where amount of push defines 'mass and energy is only the motion property of matter - including waves of such matter. In classical Gilbert-Newton signal attraction physics, matter chiefly has the signal-response property and energy is only matter response - including waves of such matter. But of course many physicists now claim that there are 'non-matter waves' and 'non-matter energy', often omitting firm definitions as of mass, as in theories like the Quanta Physics of Vertner Vergon. And some of such physics theories also claim that non-matter waves and/or energy somehow have a push property as in the ElectroMagnetic Radiation Pressure (EMRP) gravity theory. Descartes matter push has a well defined mechanism, from two pieces of matter being unable to occupy the same space at the same time, but the EMRP 'push' really seems to be more some unexplained moving away that maybe cannot be properly called a push (eg see www.blazelabs.com/f-g-intro.asp). But the basics of Descartes push physics have perhaps still not been firmly disproved, since it remains somewhat doubtful that light or any form of energy has yet been firmly shown to be other than matter response or matter motion ?
Despite clear disproofs of substantial elements of Descartes physics, it has had one perhaps unlikely success area - in gasses, two of which seem able to occupy the same space and do not appear to push each other. Yet today's standard 'Kinetic Theory' of gasses is simple Descartes push physics theory assuming microscopic gas molecules are solid moving balls, though with no Descartes ether, and it seems OK at explaining gas temperatures, pressures and wave motions including sound etcetera. So Descartes push physics maybe lives on for the macroscopic behaviour of gasses, as Gilbert-Newton attraction physics lives on for the common behaviour of gravitational and magnetic bodies. (Of course Descartes physics needs an ether to try to explain at-a-distance forces like gravity, and an attraction physics can undoubtedly also explain gasses and maybe more convincingly.)
But attempts to prove modified Descartes general physics theories still continue, as with Steven Rado's 'Aethro-kinematics' push physics which basically is Descartes physics with ether vortex-motion replaced with ether torus-motion to 'explain' gravitational, magnetic and other forces. It is not clear that its ether torus-motion has any real basis, though it is partly supported by some interesting experimental torus-model evidence - see www.aethro-kinematics.com/. But in any case the known experiment mathematics of these forces does not agree with the known experiment mathematics of vortex/torus motions - so the latter cannot give the actual elliptical orbits of the planets and where 3 gravity forces can add as 1 force from a common center of gravity, 3 vortex/torus motion forces cannot add in that way so a Newton-disproof still holds. (a similar problem also seems to apply in trying to add multiple space-curvature forces, as balloons expanded 1 percent or 3 percent do not exert proportionately more force ?) But the physics or physical chemistry of gasses is still now generally explained in terms of Cartesian push physics usually without mentioning Des Cartes or considering any possible alternative explanations.
Some supporters of Descartes physics, as Einstein for his physics, have and do claim 'compatability with Newton' falsely. To the extent that they define their mechanisms both Descartes and Einstein seem to require basically similar push mechanisms for planetary motion, which Newton proved are not compatible with his planetary motion or with actual planetary motion. For either theory to be viable they seem to need gravity mechanisms different to their claimed mechanisms. The currently best developed Descartes push physics theories are perhaps Particle Exchange Quantum Mechanics and Lorentz-Fitzgerald Ether Fieldforce Theory, which may well both involve the same mathematics as a properly developed Gilbert-Newton signal response physics. These three may well be valid image theories.
For comparison with other physics theories, Descartes three laws of
motion would be ;
1. Every body will remain at rest, or in a uniform state of motion unless pushed or pulled.
2. When a body is pushed or pulled, it accelerates proportional to the force of the push or pull and inversely proportional to the mass of the body and in the direction pushed or pulled.
3. Every push or pull has an equal and opposite reaction.
PS. For some modern Descartes physics, with a fair sprinkling of some other 'non-mainstream physics', see the Natural Philosophy Alliance and the World Science Database - at //thescientificworldview.blogspot.com and //www.worldsci.org.
You should be able to read here Descartes 1644 Principia
Philosophiae (Principles of Philosophy) but somehow the original
seems not available online anywhere. But an online English
translation of part of it is available and discussed here.
Or if you might want to buy Descartes books in our USA Descartes books or UK Descartes books sections.
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