Daniel's journal was a journal with an embossed leather cover. It was given to Daniel by his mother Eloise Hawking after he attained his doctorate. It contained a collection of notes kept by Daniel Faraday since his time as a professor at Oxford University's Queen's College Physics Department. During the events of "The Constant", while trying to help Desmond, Daniel frantically looked for the journal, and used it to aid Desmond when Desmond became unstuck in time. Daniel used the journal in "There's No Place Like Home, Part 1". Caesar later found a photocopy of one of the pages of the journal in a folder of assorted maps and notes in Ben's office at the Hydra facility. ("The Life and Death of Jeremy Bentham") The journal is the topic of a deleted scene from the Season 4 DVD. (Season 4 Deleted Scenes transcript)
Within the main storyline
Among other notes and experimental data, it contained the final correct settings for the consciousness time-transporter device used in the experiment with Eloise, and a note which read, "If anything goes wrong, Desmond Hume will be my constant." ("The Constant")
After his trip to Ann Arbor, Daniel's journal contained two pages (perhaps more) dissecting a hydrogen bomb and its components, giving detailed instructions on how to remove its core. After Daniel's death ("The Variable"), Sayid utilized this information to remove the core of Jughead. ("The Incident, Part 1")
In "Follow the Leader", just after shooting Daniel, Eloise flipped through the pages of his journal. As she did so, a freeze-frame revealed the name "OBAMA" written on one page, before she arrived at the front of the journal, where her future self had inscribed the journal to Daniel.
Within the Flashsideways
The musician Daniel Widmore told Desmond Hume that he met a redheaded beauty in the museum and it was like he already loved her. That same night after he saw that woman, he woke up and wrote formulas and diagrams in his journal. Not understanding what he had done, he took it to a friend at Caltech who was a math whiz. The friend said that it was quantum mechanics and that the equations were so advanced that only someone who'd been studying physics their entire life could have come up with them.
On one of the pages, it referenced "The Lorentz Invariance". Also known as "the Lorentz covariance", it is an actual property within physics. It's a key property of spacetime that follows from the special theory of relativity, where it applies globally. It was created by Nobel Prize winning Dutch physicist Hendrik Antoon Lorentz (July 18, 1853 – February 4, 1928). Hendrik Antoon Lorentz's data in various fields was later interpreted by Albert Einstein.
Another reference was made to the Kerr metric. The Kerr metric is used in general relativity to describe the geometry of spacetime around a rotating massive body, also known as a black hole. The Kerr metric is an exact solution for Albert Einstein's field equations of general relativity. These equations are highly non-linear, which makes exact solutions very difficult to find.
In "There's No Place Like Home, Part 1", Daniel flipped through his journal when he heard that Keamy and his men were headed toward the Orchid. Before he landed on the right page, another page was visible. The text read:
- Using Eddington-Finkelstein
- Coordinates (V, R) removes (?) the
- Singularity at R=2m As R gets
- Smaller - Light Cones tip over.
This is all a reference to the Schwarzschild metric that was based on the Eddington-Finkelstein coordinates. The metric proves time travel in general relativity as opposed to the Minkowskian metric which is meant for 4-D real linear space. Physically, the tipping of the light cones [which are traced out by null geodesics (a coordinate invariant idea)] is an indication that timelike observers traveling across the horizon cannot escape back out beyond the horizon. In general relativity, an event horizon is a boundary in spacetime, an area surrounding a black hole, inside which events cannot affect an outside observer. Light emitted from inside the horizon can never reach the observer, and anything that passes through the horizon from the observer's side appears to freeze in place, with its image becoming more redshifted as time proceeds.
- Physics forum entry on Schwarzschild metric using Eddington-Finkelstein coordinates
- Wikipedia entry on Eddington-Finkelstein coordinates
- More discussion of Faraday's Journal and the Hatch Map