Time travel

Time Travel is the concept of movement between certain points in time, analogous to movement between different points in space by an object or a person, typically with the use of a hypothetical device known as a time machine. Many different ideas of time travel exist, such as the physics behind it, its effects and how the process of travelling through time would feel and look, both to a time traveler or a person observing the time traveler.

The four main types of time travel (in fiction) are: temporal paradox, causal loop; multiverse time travel; time loop. In real life, the only form of time travel - currently - is known as time dilation (see: Time dilation on Wikipedia), which is when two things or people are travelling through time, or experiencing the process of time, as different rates. For example, an astronaut in space would experience time slower than those on Earth and, therefore, would age slower than those on Earth. This is also titled as "The twin paradox".

Ryan George Cinematic Universe
In the RGCU (Ryan George Cinematic Universe), the history of time travel and its creation hasn't been explored. However, time travel has already been invented by the 1990s and is something that the public have knowledge of. In the nineties, the talk show "The 90s Talk Show" holds a time machine that is used by Time Travelling Reporter Guy to travel to the future in. It's unknown, however, whether or not the time machine is in fact owned by the people on the show or if it is temporally lent to them for some unexplained reason (see: THE FUTURE IS DUMB)

Physics
Not much is known about the physics behind time travel and the process of travelling through time. However, it is stated that a physical time machine is what allows Time Travelling Reporter Guy to travel forward into the future (see: Time Traveler Discovers TikTok and Social Media - THE FUTURE IS DUMB) It's also shown that the time machine remains in 1995, while Time Travelling Reporter Guy is zapped into a different point in time, which shows that the time machine teleports people through time rather then taking them through time. This is confirmed when Time Travelling Reporter Guy's foot stayed in 1995 inside the time machine, due to a malfunction that The 90s Talk Show Host assured Time Travelling Reporter Guy was going to be repaired.

Rules
Once again, even though time travel hasn't really been explored any further than the fact that it exists, it can be concluded - based on what's been shown in THE FUTURE IS DUMB series - that whatever happens must happen; the past, nor future, can be altered in any way. Everything is predestined. This can be evident with the fact that - even though Time Travelling Reporter Guy talks about information about the future - events still turn out the exact same way. This also means that Time Travelling Reporter Guy is causing a bootstrap paradox - a paradox where event A causes event B which then causes event A (this ties into causal loops). In this case: Time Travelling Reporter Guy is learns about social media in 2018, which he then talks about in 1995, which then leads to social media being created in future. This is could also possibly be a predestination paradox. The idea that the timeline, in the RGCU, is fixed is also supported by the fact that the The 90s Talk Show Host always dies in 2004 (see: Time Traveler Discovers 'Solo: A Star Wars Story' - THE FUTURE IS DUMB), even though he already knows his death is in that year (see: Time Traveler Discovers Social Distancing - THE FUTURE IS DUMB). After being informed about the flat earth idea being popular in 2020, 90s Talk Show Host said that he was going to spread the word of flat earth, which may have then led to its popularity by the time 2020 came around (see: Time Traveler Discovers TikTok and Social Media - THE FUTURE IS DUMB).

Is it possible, however, that the timeline is not predestined, and the future hasn't been written. The 90s Talk Show Host told Time Travelling Reporter Guy that the producers of the show have prevented acts of changing past events (see: Time Traveler Discovers TikTok and Social Media - THE FUTURE IS DUMB). The 90s Talk Show Host has also pleaded with Time Travelling Reporter Guy to help him not to die, which suggests that his death can be stopped.

Parallel timeline
Captain America was unfrozen and awoke in 2018, instead of 2011, and was told about global problems in that year as well as Donald Trump and Beyoncé (see: If Captain America Had Woken Up In 2018).

Elsewhere

 * A Pitch Meeting episode was made about Back to the Future - a 1985 movie about time travel. Avengers: Endgame - a movie which also featured time travel - had a pitch meeting episode made out it.