Hyperbolic Time Chamber

The Hyperbolic Time Chamber, aka the Room of Spirit and Time, is a location that can be accessed through different doorways throughout Universe 7.

When using the entryway to the Hyperbolic Time Chamber through The Lookout on Earth, one year inside the chamber is the equivalent to one day on the outside. A step over the threshold of the training area brings one immediately into ten times Earth's gravity (the same as that of Planet Vegeta, Planet Zoon, and North Kai's Planet); the air gets denser, and the temperature fluctuates, the deeper one goes into the training area.

When using the entryway that the Galactic Patrol use on an alien planet, three days inside the chamber is equivalent to one day outside.

Description
The Hyperbolic Time Chamber is a separate dimension from that of Earth. There is no night or day in the Room, but the surroundings remain a constant bright iridescent white aurora. Its reflective floor is of undefined area, and the Room's boundaries are thought to stretch to infinity in all directions even though it appears to have a definite atmosphere, limiting its size to about that of the Earth. Those talking in the chamber have an echo in their voices akin to when a character thinks a word, rather than says it aloud. However, there are no solid objects other than the entrance for the sound waves to bounce off of.

The Hyperbolic Time Chamber has an entrance at its center, located in a central building with two side wings with housing, food supplies, bathing quarters and sleeping quarters. There are dual giant hourglasses of emerald sand adorning the sides of the building that count down a year within the chamber. A clock on the dome roof of the main part of the building tells the applicable time in the real world. The wooden door entrance is a portal between the Earth and the Hyperbolic Time Chamber, and is the only way to travel to the pocket dimension without ripping holes in the dimensional walls.

Training Conditions
The Hyperbolic Time Chamber is a place where one can train and get stronger in a short amount of time. There are a number of conditions that make the Time Chamber a perfect place to gain strength quickly. To begin with, the flow of time within the Chamber is compressed. One day of real world time is equivalent to one year inside the Chamber, or one minute of real time is approximately six hours, five minutes, and 15 seconds in the Chamber.

The gravity in the Hyperbolic Time Chamber living area is described as being "different", though it seems to not be much higher than Earth's gravity of 1g. Alternatively, the gravity of the training area outside the living area is 10g. Gohan's first step over the threshold of the training area brought him to his knees (this does not happen in the Dragon Ball manga, which explains how the gravity could feel "different" in the living area); Trunks also had some difficulty with the gravity, but Goku and Vegeta were both well accustomed to much higher levels of gravity by the time they used the chamber.

The temperature in the training area fluctuates rapidly, ranging between a freezing -40 °F (-40 °C) and a scorching 122 °F (50 °C).

Limits
The Initial Chamber can only be used for two days (or two years) by any given person, meaning a person can only enter the chamber twice in their lifetime, assuming they stay for the full year both times. Staying in the chamber for two days straight counts as two uses. If anybody attempts to use the chamber past their 48 hour limit, they will not be able to exit, leaving them trapped in the nothingness and not allowing anyone else to use the outside door.

Furthermore, there are only enough provisions to accommodate two people for one full year. This is commonly misinterpreted as a two-person limit overall, but it should be noted that in the Buu Saga four people in total were inside the chamber.

Improvements
The room's door is eventually destroyed, rendering it useless and temporarily trapping several characters inside. The Time Chamber has since been reconstructed by Dende, but with a number of improvements, dubbed the Updated Hyperbolic Time Chamber.

The two-time limit that a person can enter the Time Chamber has been removed, as Vegeta has used the Time Chamber at total of five times; twice in preparation for fighting against Cell, once with Goku to train for the tournament against Universe 6, a fourth time to train for the fight against Goku Black and Future Zamasu, and for a fifth time in the to train for the Tournament of Power. Additionally, this new chamber can be used for at least three days (or three years) in a row.

The new room also apparently lacks the old chamber’s weakness of having a destructible door, as Goku states, "No matter how far we take things here, we don't have to worry about destroying anything." This means that people training inside the chamber can go all-out without having to worry about destroying their only exit.

Approximate Time Dilation
When using the Earth entry, time passes 365.24 times faster in the Hyperbolic Time Chamber than in the Living World, making one day outside the chamber equal to 365.24 days within it (one solar year).