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Final Answers
© 2000-2023   Gérard P. Michon, Ph.D.

The Vacuum

 Otto von Guericke (1602-1686)  Blaise Pascal (1623-1662) Natura abhorret a vacuo.
Nature abhors a vacuum.
La nature a horreur du vide.
 Michon
 

Related articles on this site:

Related Links (Outside this Site)

A Short History of Vacuum  (McAllister Technical Services).
Vacuum Technology  by  Pr. Roy Schmaus  (formerly @ University of Alberta)
Drude model of Casimir effect  (Lamoreaux, Tang & al., 2012)
 
Wikipedia :   Vacuum pump  |  Ultra-high vacuum  |  Casimir effect  |  Zero-point energy  |  Vacuum state

The Vacuum Catastrophe (11:35)  by  Matt O'Dowd   (2017-11-02)
 
La notion de vide (French, 1:06:00)  by  Etienne Klein   (CEA, 2019-03-14).
La pression atmosphérique (French, 5:16)  by  Etienne Klein
(Matière à contredire, 2019-03-15).

 
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 Aristotle 
 (384-322 BC)

A Short History of the Vacuum


(2011-08-20)   Horror Vacui
The  plenism  of Aristotle and its downfall.

 Come back later, we're
 still working on this one...

Wikipedia :   Horror vacui  |  Otto von Guericke (1602-1686)


(2019-07-19)   Sprengel Vacuum Pump   (1865)
What made  Crookes tubes (1875)  and  lightbulbs (1879)  possible.

 Come back later, we're
 still working on this one...

Sprengel pump (1865)   |   Hermann Sprengel (1834-1906)
 
The most efficient pump ever? (20:17)  by  CodyDon Reeder  (Cody's Lab, 2017-02-04)


(2011-08-21)   Vacuum Tubes:  Electronics  before semiconductors.
Heated filaments, grids and electrons moving in a vacuum.

Richardson-Dushman law of thermionics :

 Come back later, we're
 still working on this one...

Owen Willans Richardson (1879-1959)


(2005-07-05)   Dirac's equation
How positrons were predicted before they were discovered.

The linearity of Schrödinger's equation was considered fundamental by Paul Dirac and other pioneers of the "new" quantum theory  (which sought to explain the various quantizations that the "old" quantum theory had to postulate.

 Come back later, we're
 still working on this one...


(2011-08-20)   The Quantum Vacuum
The Vacuum isn't Empty.

 Come back later, we're
 still working on this one...

Empty Space is not Empty (4:45)  by  Derek Muller   (Veritasium, 2013-04-30).
 
Zero-Point Energy Demystified (10:08)  by  Matt O'Dowd   (2017-11-08).


(2023-03-01)   The Massles Vacuum
Whatever is in it must propagate at speed c.

In other words, it's reasonnable that every component u of such a wacuum statisfy the wave equation:

   2 u     =     2 u   +   2 u   +   2 u  
Vinculum Vinculum Vinculum Vinculum Vinculum
c 2 t 2 x 2 y 2 z 2
 
 =DU [D is the Laplacian operator]

Any covariant derivative of a combination of such components is a linear combination of components and their derivatives so that if you apply it twice, the above equation is retrieved.  This imposes a definite internal symmetry among components.  Conversely, only those operators which respect the wave equation are called covariant.

A single component forms what's called a scalar field  (spin 0).

A 4-component field is either a vector field (spin-1 like the electromagetic field) or a spinor field (spin ½ as used in the dirac equation for the electron).

The leeway in building such things is provided by 4-dimensial dirrerential operator that vanish  (in 3 dimensions, the divergence of a rotational and the rotational of a gradient both vanish).

 Come back later, we're
 still working on this one...

Empty Space is not Empty (4:45)  by  Derek Muller   (Veritasium, 2013-04-30).
 
Zero-Point Energy Demystified (10:08)  by  Matt O'Dowd   (2017-11-08).

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