What is the difference between a Parallel Universe and an Alternate Universe?

Answer 1

Parallel Universes, if they exist, are experiencing time in your time frame and in tandem with your existence, but in another dimension (there may be an infinite number). Alternate Universes might exist outside of our Universe with totally different physics and therefore not within our scope of reality. The Alternate may simply be what is beyond our known Universe.

Answer 2

It could be either, depending on how the new Earth is connected to ours. I've usually heard the terms as "parallel universe" and "alternate history". A parallel universe is normally the same as ours with some key difference. The best-known example is probably the Mirror Universe in Star Trek, where the same species and technology exist as in our universe, but the Federation is an Empire, and all the characters we know from the real show exist as evil versions of themselves. An alternate history is where a new universe branched off ours at some point in the past, after which it developed in its own way, so that it could be radically different from our universe on any given date. The one everyone's heard of is "The Man in the High Castle" by Philip K Dick, set in a world where Germany and Japan won the Second World War. The turning point is some years before the start of the war - Roosevelt was assassinated early in his presidency (the attempt happened in our world too, but he survived). The man who replaced him was much more determined to keep America out of the war, and so didn't help Britain or build up the American military. Britain fell to the Germans, and Japan's attack on Pearl Harbour was much more decisive. The man of the title is a novelist who's written a book set in an alternate history in which Germany and Japan lost the war, albeit in a different way from how it happened in our world...

Answer 3

Some theories on the nature of reality require the universe to have more than the 3 dimensions that we can easily observe. If there are more than 3 dimensions, then theoretically, it is possible for there to be more than one 3-dimensional "universe".

Imagine if we only existed in 2 dimensions, like a sheet of paper. Well, if the universe really had 3 dimensions, you could have a whole stack of 2-dimensional "worlds". Since each 2-d world would never touch another, they would all be "parallel", and an inhabitant of one world or one "universe" might never know that the other ones exist.

If the universe has, say 4 or more dimensions, it might be possible for more than one of our 3-dimensional worlds to exist. If they were "parallel", we'd never know about the other ones. They would be "parallel universes".

An "alternate universe" could be just about anything. Possibly, everything in an alternate universe would be made of anti-matter, or something like that. Or, the term "alternate universe" could be just another way to describe a "parallel universe" like the one I mentioned above.

Answer 4

Aren't they the same thing?

Parallel universe
From Wikipedia, the free encyclopedia
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Parallel universe may refer to:

Multiverse, the hypothetical set of multiple possible universes.
Parallel universe (science), including
Many-worlds interpretation, of quantum physics.
Parallel universe (fiction), alternate universes, worlds, realities and dimensions in fiction.
Alternative universe (fan fiction), fiction by fan authors that deliberately alters facts of the canonical universe they're writing about.
List of fiction employing parallel universes.
Parallel Universe (album), by 4 Hero.
"Parallel Universe" (song), a song by the Red Hot Chili Peppers.
"Parallel Universe" (Red Dwarf episode), an episode of Red Dwarf.
Parallel Universe (film), a film company
Multiverse (DC Comics), the multiverse within the fictional setting used by DC Comics.
Multiverse (Marvel Comics), the multiverse within the fictional setting used by Marvel Comics.
Mirror Universe, a fictional parallel universe in which several Star Trek television episodes take place.
Parallel Universes - a BBC/Horizon documentary

Answer 5

I agree with LIzD, but I think everyone who uses these terms has their own unique idea of what they mean.

Answer 6

Neither exists.