An effort to compile data about the theories and what not discovered on the whiteboards throughout Black Mesa and Xen.
You can find images of the whiteboards discussed here
Earthbound WhiteboardsEdit
Summary of whiteboard subject mattersEdit
Whiteboard  Subject matter 

c0a1x_labboard_am1  Lorentzian wormhole theory 
c0a1x_labboard_am2  Crystal geology 
c0a1x_labboard_am3  Some kind of mass spectrometry 
c0a1x_labboard_am4  More Lorentzian theory 
c0a1x_labboard_am5  Rocket fuel 
c0a1x_labboard_am6  Nuclear alchemy 
c1a1x_labboard_uc1  Cryogenics 
c1a1x_labboard_uc2  More cryogenics 
c1a1x_labboard_uc3  More cryogenics 
c2a4x_labboard1  Schematic for the lasers and some easter egg stuff 
c2a4x_labboard2  Various explanations as to how things work on the tau 
c2a4x_labboard3  Something to do with nuclear weapons 
c2a4x_labboard4  Hawking radiation 
c2a4x_labboard5  Decay of particles (tauons) and how they are focused into beams 
c2a4x_labboard6  Quantum field theory 
c2a4x_labboard15  Budget discussion. Message to Anthony not to steal Dr. Horns pizzas. Mention of cascade ciphers (AESTwofishSerpent.) 
The Dr. Bottomley / Dr. Horn Whiteboard aka "The Big One" — SOLVEDEdit
This whiteboard is the one with the notorious lines of code on it. Except for basically explaining in black and white (literally) how to activate the large laser at the end of the level, it makes a couple of references:
 1.21 GW is a reference to the amount of electricity needed to power the DeLorean time machine in Back to the Future
 There is a scribble by Dr. Horn: "'DO NOT WIPE BOARD! DR. HORN"'
 Another scribble says: "NB  DO NOT ALLOW SECURITY OFFICER SISK NEAR MY PIZZAS  HE WILL EAT THEM >: (  DR. HORN"
 v = f λ is written on the topleft half of the board. It is a reference to sinusoidal wavelengths and the equation explains how the constant velocity (v) of a wave (also referred to as the "phase speed" of the wave) is equal to the frequency (f) of the wave times the wavelength (λ) of the wave.
The cipher on this whiteboard has been solved. See Code D for more information.
Cannon DiagramEdit
The Accelerated Lepton Optronic Linearity CannonEdit
Ain't that a mouthful? Anyway, this board appears to break down the laser cannons that are found throughout the labthe ones necessary to completing the final laser puzzle. The schematic is pretty detailed, and there are a few interesting equations on the board. Boy, doesn't that lambda look familiar? Anyway, here's what this board has to offer:
 Another signature by Mr. Horn: "DO NOT WIPE BOARD! DR. HORN"
 The equation encased by a yellow cloud is the equation for (drumroll!) a halflife! In other words, the halflife (t1/2) of the decaying quantity is equal to the natural log of 2 (ln2) which is equivalent to 0.693 divided by the decay constant (λ) of the decaying quantity; or t1/2 = ln2 / λ
 The linegraph with the solid, red and dashed lines is an explanation of the SunyaevZel'Dovich effect (SZE) on a cosmic microwave background (CMB) spectrum. To put a long story short, it's explaining how the SZE (solid line) increases the CMB (red line) at higher frequenciesalthough it lowers the CMB at lower frequenciesthus making it possible to view galaxies in a stronger light. In other words, CMB is radiation that floats around in space, and by measuring it scientists can get a better picture of where things lie. The SZE is especially useful because it can be measured to determine how far away things are from Earth by using proportional data gathered from SZE signatures. The dashed line is probably just there to show the correlation / slope of the graph.
 The formula under the linegraph, kBTe / mec2, is a MaxwellBoltzmann distribution in which "the kinetic energy distribution of electrons, ions and neutrals" is observed. The equation shown here is one derivation of the equations needed to calculate the temperatures of the involved particlesthis one is used to calculate the temperature of the electron in the distribution. The formula to calculate the temperature for the ion is similar, and is "kBTi / mec2". These formulas are generally used to determine how much kinetic energy is dissipated into thermal energy.
 The diagram is of the actual ingame weapon Tau Cannon
 The title could be an acronym for A LOL cannon.
Alchemy boardEdit
 See: Lapis Philosophorum
Xen WhiteboardsEdit
Circled lettersEdit
Five of the whiteboards contain circled letters: L O C U T S
"LOCUTS" is only missing another letter 'U' from spelling "Locutus", which is one of the circled names on Dr. Horn's "conspiracy" whiteboard. It is shown as the link between the "Sphere of Chon" and the 21 into 1 figure.
Locutus is a latin word that means spoken, having spoken, or he who has spoken. It is also a reference to Star Trek TNG, where Locutus of Borg was the Borg designation forced upon Starfleet Captain JeanLuc Picard after he was assimilated by the Borg.
One theory about the circled letters is that they might indicate an order in which to read the whiteboards.
Another theory is that the missing letter (U) was intentional and indicates that Storm is telling us that the only thing missing from HALOS being complete is ‘YOU’ and that the 'reward' being offered to the first person to solve this mystery will be their involuntary incorporation into HALOS.
Xen A whiteboard #1Edit
Equations on the top leftEdit
 Abbe number
 Sellmeier dispersion equations
 Complex refractive index
 Equations for calculating the vector of a refracted ray using Snell's law and geometry/trigonometry.
Nano Lens Cross SectionEdit
This appears to be a diagram of a nanowire array hyperlens (see Superlens).
Text in the diagram:
400nm [length]
200nm [diameter]
Object Plane
Image Transfer
Image Plane
'Prismatic ExMat EP0021'
(see Lorentz model.)
Text above the top middle diagram:
Use specimen samples in fabrication of nano lenses triple array.
Text next to bottom middle diagram:
Nano lens substrates.
Modular formed metamaterial.
EM Wave Polarization DiagramEdit
To the right is a diagram showing linear and circular polarization of electromagnetic (EM) waves. Below the diagram are equations related to that.
Red text at the bottom leftEdit
NB. SAMPLES TO BE
AQUIRED FROM
SECTOR C  CLASSIFY LEVEL 8
 DR HORN
Equations on the top rightEdit
Equations combining Coulomb's law ('CL') and Newton's law of universal gravitation ('NL'). Mass is interpreted as 'Gravitational charge'.
Xen A whiteboard #2Edit
TranscriptEdit
Text on the left:
RECIEVING SURFACE Use diffused scattered surface and organise photons via scattering analysis. Gallium Phosphide used to slow light. (GaP)  Em = 250 cm^{2}(V^{1}s^{1}) (300 K). Image reconstituted with needle beam formed optronic laser surface plasmons to form focus. Crystalline metamaterial anisotropic hyperlens development must continue around remaining further 'far field' limiting factors using spherical instead of cylindrical to improve the hyperbolic dispersion of visible spectrum light to between 90nm and 200nm. This should allow for molecular level accuracy resolutions for the projection system. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NB  Propagation of evanescent waves to increase resolution (use focus array Lab D)  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 
Em = Electron mobility
Text on the bottom right:
Charge density oscillations or surface plasmonpolarization waves. Using the high resolution evanescent wave forms it should be possible to gain full colour hyper resolutions through the proposed array. 
Xen A whiteboard #3Edit
On this whiteboard there are references to the X01/X02 labs as well as HALOS.
TranscriptEdit
Text in the middle:
Construct each prism lens base from used samples of exotic matter. Trigonal axis orientation allows for splitting to create lens interfacial angles. Most samples have partial conformity with constancy of interfacial angles. Bi refringence optical qualities need digitising for wave refraction corrections.

Text on the right hand side:
Full colour projection will occur at higher resolutions should the beam photons be focused more using a needle beam optronic laser. Use focusing arrays in labs X01 and X02, keep flux dispersal regulated with 500MW694.3nm ruby booster (temp for testing only.) Booster used for HALOS binary stream normally. 
Xen A whiteboard #6Edit
A secret messageEdit
The red numbers in the supply manifest list hide a secret message: “SOYOUTHINKTHISISASECRETMESSAGE”
Decoded via JavaScript by faed:
'19 15 25 15 21 20 8 9 14 11 20 8 9 19 9 19 1 19 5 3 18 5 20 13 5 19 19 1 7 5'.split(' ').reduce((acc, num) => (acc + String.fromCharCode(64+parseInt(num))), '');
Supply drop scheduleEdit
NEXT SUPPLY DROP
In  Mon  07.30
Out  Mon  09.00
[to LC SE complex]
Leave time for transit to Biodome  call Sezen Ex 0013
Team rostersEdit
On the right hand side of the whiteboard we find rosters listing four science teams.
TEAM 1 — Geosurvey 1  Biolab 1A stage.  

Mirfin  Fanaris 
Olsen  Geslot 
Kemp  Palamar 
Makinen  Burnell 
TEAM 2 — Site 8 forward obs.  OP2  Alert 1. 

(?) 
(?) Foreman [MIA] 
(?) Nielsen [MIA] 
(?) Stone [MIA] 
TEAM 3 — Site 8 recovery 

Junek ← lead. 
Welsh ← survey. 
Hubi ← comms. 
TEAM 4 — Site 3C obs.  

Jaggi  Dr Yiu  Team Specialist [provide flamethrower] 
Tsarouhas  
Soderberg  
Sunabouzu 