# Tag Info

25

If anyone's still reading this thread, here's a few more data points that appear to back Feynmann's interpretation. Erik Bäcklin, Nature vol 123, no. 3098, p. 409 (1929): $1.59875 \cdot 10^{-19} \pm 0.004796 \cdot 10^{-19}$. Wide error bar overlaps Millikan's. Gunnar Kellstrom, Phys. Rev. 1935: $1.60709 \cdot 10^{-19} \pm 0.011 \cdot 10^{-19}$. ...

20

The 16th (1995) edition of Kaye and Laby includes the following progression of the accepted values for the charge of an electron. The first value "is essentially Milikan's oil drop value" and the second is "the 'X-ray grating' value". I couldn't find any more details about the actual experiments. The standard errors are often over-optimistic, indicating ...

19

Marie Curie is probably the most famous example of a person who died of the effects of radiation (handling a lot of radium mostly - for the discovery of which she won the Nobel prize in Chemistry). In general, people were indeed very ignorant of the effects of radiation. A couple of examples: Shoe shops used to have an X-ray machine to look at the "fit" of ...

17

Note: I present here some information defending Millikan, but please note that I do not necessarily agree with the article it came from. From the feature article "In Defense of Robert Andrews Millikan" by David Goodstein (American Scientist, January-February 2001): Awkwardly, an examination of Millikan's private laboratory notebooks indicates that he ...

16

As quoted from this article: Many people's work was needed to prove that the Sun is a star. The first person we know of to suggest that the Sun is a star up close (or, conversely, that stars are Suns far away) was Anaxagoras, around 450 BC. It was again suggested by Aristarchus of Samos, but this idea did not catch on. About 1800 years later, around AD ...

15

In Millikan's publications, he stated categorically that every single oil drop observed had had a charge that was a multiple of $e$, with no exceptions or omissions. But his notebooks are full of notations such as "beautiful data, keep," and "bad run, throw out." Richard Feynman wrote an essay called "Cargo Cult Science," in which he pointed out: ...

14

The principle was known long ago, to the Babylonians and Hellenistic Greeks but the accuracy of prediction depends on the detail of the Lunar motion (the motion of the Sun is relatively simple). Without a precise Lunar theory, it was possible to predict that an eclipse is LIKELY to happen on such and such date and time, but not with a 100% certainty, and the ...

12

It all depends on your definition of a telescope. Digges absolutely built some sort of device that was capable of magnifying objects. It seems that is agreed upon. But the divide is really about whether or not this was a telescope. Some historians shrug it off as little more than a powerful spyglass; others herald it as the first telescope. There are ...

12

As it turns out, it was already known by some philosophers from the 1200s that certain types of rocks naturally tend to rotate to point north. However, they had no idea why: For instance, it was generally thought that compas needles were attracted by the Pole Star. Some more serious work on compasses (e.g. discovering the 'magnetic dip') was first done by ...

11

Today, sky coordinates are measured as "Right Ascension" (RA) and declination. These are similar to the angular coordinates we use for the Earth's surface but are measured on the celestial sphere relative to the celestial equator and pole. By using the current sidereal time, it is possible to map the local sky coordinates (ie. a horizontal bearing relative ...

11

Let me clarify first that there are deep conceptual issues with what $E=mc^2$ means, and what it means to verify it. That energy contributes to inertial mass was known before Einstein. In 1900 Poincare showed that electromagnetic field has momentum, hence effectively mass, and implicitly gave it as $E/c^2$. Austrian physicist Hasenöhrl even wrote explicitly \$...

11

The idea that matter was made up of "primordial" particles, and currents in metals consisted of them was well established by then. Stoney suggested the name "electron" in 1891, and Lorentz's theory of electrons dates back to 1892, see Wikipedia's timeline. Thomson himself mentioned Prout as the source for the view, and saw his task at hand more in ...

10

The question is delicate because of the phrasing that assumes empirical approach, which did not emerge until 17th century. And the notion of "speed" as applied to sound presupposes the concept of wave in a medium, which dates to late Renaissance. The use of "speed" in antiquity was mostly confined to uniform motions of localized objects, not light or sound. ...

10

It's hard to quantify the negative effects of radiation. In 1978, a Russian scientist was struck by a particle accelerator beam during routine experimentation. He saw a flash "brighter than a thousand suns". He survived and even finished his PHD, although the beam left a wake of destruction in its path, giving him seizures and partial paralysis. You think ...

9

See the detailed discussion on : Stillman Drake, Galileo at work, (1978), page 414–16. In 1641 Galileo’s successor on the chair of mathematics at Pisa, Vincenzo Renieri, experimented with bodies made of different materials dropped from the leaning tower, finding that a lead ball fell faster than a wooden one. Drake discuss at lenght about the fact ...

9

Young's original setup demonstrating interference of light was not double slit but sunbeam splitting with a single thin card. He presented a paper On the theory of Light and Color to the Royal Society in May 1801 published Proceedings of the Royal Society of London A 92 (1802) (see here and here), and in November 1803 gave a public talk Experimental ...

9

Newtonian mechanics was not yet in place when Hooke published his De Potentia Restitutiva (On Restoring Force) in 1678, Newton's Principia only came out in 1687. Hooke inferred the law from experiments not only with springs but also with wood and a "body of air", concluding: "The power of any spring is in the same proportion with the tension thereof: ...

9

I am afraid nobody noticed it, because nobody could have noticed it. A deviation is only a deviation when one has something that it is a deviation from. To "notice" the Magnus effect one has to operate from a theory that predicts a parabolic trajectory, and be able to separate the subtle deviations caused by spin from other deviations. Hall even wrote that ...

8

Cox et al. 1964 gives a good account on the different steps of how this discovery was made. The most important first step was to acknowledge the fact that some rocks (namely magmatic rocks) acquired a remanent magnetism based on the magnetic field in which they were "cooked" (Brunhes 1906). Followed observations of different directions in remanent magnetism ...

8

At the time of Brahe and Kepler they did not use the right ascention and declination to record the movement of planets. These coordinates are related to the Earth, and it is known since the times of Hipparchus and Ptolemy that one has to use the ecliptic coordinates, that is a system related to the Sun motion. (Ecliptic is the large circle in the sky on ...

8

There is inherent vagueness in dating "predictions" and "confirmations" in many cases. For instance, who predicted heliocentrism? Copernicus, Kepler, Newton, perhaps Aristarchus? When was it confirmed? Another difficulty, also present in this example, is with predictions across major shifts in science (which happened about every 100 years since 17th century)....

8

To not be measured is not to have any behavior. No dynamic is induced on any other system in the universe by this object (Rosen 1978). Objects without behavior do not exist. Their behavior is that which makes some perceptions objective not subjective things (Hutton 1794). What is measured but not found different is double counted; it does not exist in ...

8

At the time of Newton, the scientists could NOT detect any deviation of the Newton's laws from reality. As we know now, the only visible effect of this deviation in the Solar system is the anomalous precession of Mercury's perihelion. It was detected only in the middle of 19th century; it makes about 43 seconds per century, and it was not known at Newton's ...

7

This image: is the most explicit one I've found for the experimental arrangement. Here's another that is more schematic, but illustrates the basic idea: Now on to your specific questions. The light passes through the gaps between the teeth; it is not refracted. Pulses of light hit the mirror and are reflected back. In the experiment, the speed of the ...

7

The Demon Core, a subcritical mass of plutonium, went critical during two distinct incidents in 1945 and 1946. Both times, scientists were killed due to exposition to radiation. During the second incident, for example, the two sub-critical masses were separated by a screwdriver held by the operating scientist. On the fatal day, the screwdriver slipped ...

7

"Serious" in the OP sense is probably too high a bar. In 1900-s the situation was very much in flux as to what classical physics could and could not explain. Even Planck's and Einstein's ideas, that we now associate with quantum mechanics, were incorporated into seemingly classical approaches at the time. But what dominated the scene were qualitative ...

7

I think Guido makes a good point in a comment that the analogue in math would be proving an old conjecture, and for this there are many examples that were settled after over 100 years. Besides Fermat's Last Theorem there is: the Poincaré conjecture, posed around 1900 and settled over 100 years later by Perelman, the prime number theorem, conjectured ...

7

From: Discourses and Mathematical Demonstrations Relating to Two New Sciences (Italian: Discorsi e Dimostrazioni Matematiche Intorno a Due Nuove Scienze), published in 1638. See: Engl.transaltion by Henry Crew and Alfonso de Salvio (1914): A motion is said to be equally or uniformly accelerated when, starting from rest, its momentum (celeritatis momenta) ...

7

Proportionality law for elastic forces is one discovery at which Hooke did arrive first. He describes it in De Potentia Restitutiva (1678): ”The Power of any Spring is in the same proportion with the Tension thereof: That is, if one power stretch or bend it one space, two will bend it two, and three will bend it three, and so forward. Now as the Theory is ...

6

I would not call this "horrendous mistake", and I disagree with Conifold's statement that the reason was canonization by the Catholic Church. It is easier to disprove Conifold's statement, so let me begin with this. Canonization of Aristotle begins at the times of Thomas Aquinas (13 century), AFTER 1000 years of the Dark Age, and about 200 years before the ...

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