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Period: 100 to
Scientific Discoveries
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335
B.C.E Aristotle identifies four sorts of cause
Aristotle identifies four sorts of cause; Formal cause- the design of a thing, Material Cause- that of which it is made, Efficient Cause- the maker, and Final Cause- the purpose of the thing. He also states that heaven must be sphereical because that is the shape that is appropriate for its substance. -
420
B.C.E. Democritus atomic theory
Democritus developed Leucippus's atomic theory: Atoms vibrate when hitched together in solid bodies and exist in a space which is infinite in extent and in which each star is a sun and has its own world. -
440
B.C.E. Leucippus World Makeup
Leucippus said that the world consists of the void and atoms, which are imperceptible individual particles that differ only in size, shape, and position. -
450
B.C.E. Empedocles Changes in Quality and Quantity
Empedocles explained changes in quality or quantity of a thing as movement by the basic particles of which the thing consisted, Fire, Earth, Air, and Water. These elements mix and separate under the guidance of two opposing principles, Love, which draws them together, and Strife, which drives them apart. -
Daniel Rutherford Decribes Nitrogen
Nitrogen- residual air -
John Dalton Theory of the constitution of Mixed Aeriform Fluids of the Atmosphere
He formulated that the law of gaseous expansion at a constant pressure and the law of gaseous partial pressures which stated that the total pressure exerted by a mixeture of gases is equal to the sum of the partial pressure of the individual gases. -
John Dalton Atomic Theory Applied to Atomic Weights
An atom was difined as a term for a particle that is only divisible by the loss of its distinguishing characteristics. Dalton did not realize the implications of atomic weights. -
William Thompson The Uniform Motion of Heat in Homogeneous Solid Bodies and its Connection with the Mathematical Theory of Electricity
He stated that any two theories dealing with the same phenomena cannot conflict if their most elementary laws can be connected mathematically. -
William Thomson Mechanical Representation of Electric, Magnetic, and Galvanic Forces
On the basis of the FAraday effect, linked electrical and magnetic forces to the internal processes of a single medium were linked to a common element and were mechanically analogous. -
William Thomson Absolute Themometric Scale
propsed the kelvin scale -
Planck Validity of Second Law
Planck opposed the idea that the validity of second law depends on the existence of an observer or his lack of information. Meaning that irreversibility is natural. -
Joseph John Thomson Cathode Rays
Using a Crookes' tube he demonstrated that cathode rays consisted on units of electrical current made of negatively charged particles of subatomic size. Hypothesized a model of atomic structure. -
Joseph Thomson Charge of Electricity Carried by Ions Produced by Rontgen-Rays
He showed that a neon gas consisted of two tyes of charged electrons, or ions, each with a different charge, or mass, or both. This made it possible for a single element to exist with the same atomic number but differ in mass. -
Ernest Rutherford Radiation
He characterized radiation from raduium as being quite complex, easily aborbed, and stopped by a few centimeters of air. He also characterrized uranium radiation as far more penetrating. Naming them alpha and beta rays. -
J. Thomson Msses of Ions in Gases at Low Pressures
Discovered that ions have a much smaller mass than ordinary atoms; so in the convection of negative electricity we have something which involves the splitting up of an atom. -
Planck Blackbody Radiation
Theorem- E=J(T,v) -
Planck QuantumTheory
E=hf E=energy f= frequency h= a new constant 6.63 x 10 -34 J-sec accounts for expiramental data in blackbody radiation. This theory states that occillating atoms absorb and emit energy, or light only in discrete bundles. -
Rutherford Third Type of Radiation
He discovered a third type of radiation which he called gamma rays. they are made up of eletromagnetic photons -
Planck Granular Structure of Electromagnetic Radation
He discovered the first indications of the granular structure of electrogmagnetic radiation while working on the spectrum of black body radiation. -
Robert Andrews Millikan Minimum Unit of an Electrical Charge
HE determined the probable minimum unit of an electrical charge and later named cosmic rays. -
Rutherford Scattering of a and B particles
thinking about the nature of the nuclei which could produce radiation desribed that atom as a small heavy nuclues surrounded by electrons. -
Niels Bohr Constitution of Atoms and Molecules
He calculated the frequencies of the spectrum of atomic hydrogen. This supported that electrons moved around the nucleus in an orbital pattern. -
World War I
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E. Rutherford Proton
He discovered the proton, which contains the positive charge within the nucleus of an atom. -
E. Rutherford Neutron
Discovered the neutron which has a neutral charge and is found in the nucleus and serves the purpose of keeping the protons from repelling eachother. -
Werner Heisenberg Helium Atom
Was able to calculate the average wavelength of the two electron helium atom. -
Louis Victor de Broglie Hypothesis
2pi r =nh/mv -
Schroedinger Quatum Theory
Initiated development of the final quatum theory describing wave which predicted the positions of electrons, vobrating as bohrs standing waves. -
James Chadwick Curie-Jiolet Effect
He described the helium alpha particles which created the Curie-Jiolet effect as consisting of two protons and two neutrons, thus isolating the neutron, the first particle discovered with a zero charge. -
World War II
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Pearl Harbor
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Erwin Schroedinger Biology
Asked thirty questions that set biology's agenda for 30 years. -
Kennedy Assassination
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World Trade Center
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B.C.E. Plato belief vs knowledge
Plato said, in the Timaeus, that "as being is to becoming, so is truth to belief". In other words, we can only believe, not know, on the basis of experience.