Divergence Meter

Divergence Meter is a device brought back from 2036 by Suzuha, invented by the future Okabe for his own personal use.

Method of Function
It is an array of Nixie tubes which calculates and displays local gravitational variation. There is a property of gravity that is different on every world line; the Divergence Meter measures that property and compares it to the value measured in the world line where the first meter was built, displaying the difference in %. "First, a foundational measurement of local gravity is taken and then used as a value of reference, wherein after time traveling, the meter generates a local gravitational sine wave, reproducing the tenets of the Kerr Black Hole theory, then measuring gravity via the onboard gravitational distortion apparatus in order to calculate the rate of variation."Steins Gate World Line value should be measured in a similar manner, however, it isn't known to which world line meter compares its value.

Plot
Throughout the story, Okabe is trying to reach value starting with a different digit (1 in this instance) to reach different attractor field, using the meter as a reference each time.

Even Suzuha, who herself had time-traveled to bring the future device to present-time Okabe, couldn't tell if value had changed. According to Tennouji's recollections of her near the end of Episode 16, in her final year of life she was always looking at the meter to see if the value is any different:


 * Suzu-san had this. Do you know what the number means? She was always looking at it, from her hospital bed. "Is this the number before it changed or after? Did I manage to change it?" Whatever it was, it bothered her to the end. — Yuugo Tennouji

In the future time of its first invention, it was originally in Okabe's possession; when he died, it was passed on to Daru, and he passed to Suzuha. She then traveled back in time to give it to Okabe, completing the cycle.

Relevant Facts

 * Okabe is the only person able to effectively use this device, because every time the world line changes, everyone's memories are rewritten rendering them unable to distinguish the difference in meter's value. Okabe is an exception, because his Reading Steiner ability allows him to save his memories after the world line changes.
 * Divergence Meter cannot display negative values, so when value is negative it leave first digit blank.
 * Divergence Meter isn't limited to display only one value at a time; there are instances when two values are displayed simultaneously.
 * Fluctuations in divergence value behind sixth digit after the decimal point are not registered by the Divergence Meter and doesn't cause the physical world to reconstruct.

Robotics;Notes DaSH: Heliopause Processor
Spoilers for Robotics;Notes DaSH''' As of 2020, Okabe resides in the United States and researches at Viktor Chondria University alongside Kurisu and Maho. Daru mentions that after Okabe came up with the "World Line Theory", he changed significantly and migrated to study with known geniuses. During that time, Okabe reinvented the Divergence Meter to watch over the World Line. However, it is revealed that Steins Gate World Line is in a jeopardy. The meter is displaying his desired value (1.048596) as it should, but occasionally twitches, changes numbers, or glitches. This worried him enough to contact Daru, which as Hashida mentions is very rare for him. Before Okabe called him, he sent him a mysterious message titled: "The World Line is wavering".

Trivia

 * This phase begins by displaying two divergence values overlapping eachother: 1.048596 and 1.123581

In the future
Spoilers for Anonymous;Code During Anonymous;Code the Nixie Tube meter can be seen during the "Prologue 2", but in Chapter 4 the meter is introduced as a new device called M2037.

November 29, 2037
During Chapter 04, Liddie Kumar shows Pollon Takaoka the Divergence Meter M2037 and explains the function it performs. However, the Divergence Meter shows an abnormal reading displaying two sets of divergence values simultaneously active (1.048596 and 1.123581), which is something that shouldn't be. Liddie also mentions that it's necessary to have a special talent to notice a change and remember the previous value.