Is there a standard galactic time?

[Feather Scribbles 194]

As we all know, most (if not all) concepts of time that we have created are human inventions. These include seconds, minutes, and hours. Most though are directly "inspired" by the Earth - months are one such example, as are years.

The universe is supposedly 13.7 billion years old... But it's not. We are measuring the age of the universe in Earth years here.

What about light? Light's velocity is approximately 186,000 miles per second. Per SECOND. Seconds are (and correct me if I'm wrong) a human invention. Also, one light year is approximately 6 trillion miles. First of all, miles, when you think about it, are a human invention. And again, we are measuring the distance that light travels in one Earth year.

If there are truly extraterrestrials out there, they would, without a shadow of a doubt, have a different measurement of time - that is, if time is relevant to them at all.

What if the Earth took approximately 456 days to complete an orbit around the Sun? Well, if we still gauged the universe's age by Earth years, it would technically be "younger" than we currently measure it as.

Therefore... Can you name any time that could apply to the universe... that isn't "inspired" by the Earth and/or that isn't a human invention?

[Widdershins 9,960]

Well technically, Time by its nature is relative. An alien on a bike on some alien planet can still cover a mile's worth of distance, it just wouldn't be called that. Miles and Feet or Kilometers and meters are pretty much assigned arbitrarily; but Time is somewhat based more on feeling. A second should still feel like a second, but whatever that alien calls an hour may take up a hundred seconds or however their culture assigned it. Same goes for a year, their planet may have a longer revolution but we can look at it as a 1.7 ratio to ours and work the math out from there.

 So, I suppose logically & mathematically one ought go with the most basic of measurements. I vote for the Second. Surely any species seeking to measure time would say something along the lines of "time it takes to snap fingers or blink." 

 I see Measurement as a whole as being arbitrary. Feet were originally called that just because they picked the foot size of one specific king.

[Feather Spiral 1,892]

There is, obviously, a galactic time.

Aaaanyway.

First off I gotta quickly point out the discrepancy between the title of your thread and the OP. One says "galactic time", while the latter speaks of measurements applying to alien civilizations and the whole "universe". I'll cover all three cases here, going from smallest to largest, because I think they're all worth pondering about.

Now, here on Earth, we mostly express time in terms of periodic events that affect life on Earth:

• how many times the Earth has revolved around the Sun (year);
• how many times the Moon has revolved around the Earth (month);
• how many times the Earth has made one full turn on itself (day);
• plus more or less arbitrary subdivisions (hour, minute, second).

It's easy to presume another sapient alien race would use similar units, but they might also include:

• the time it takes for other celestial bodies to orbit their sun (a comet for example);
• the half-life of certain radioactive nuclides that're common on their planet;
• the time it takes for certain orbital parameters to change (the angle of their planet's axis, the shape of their planet's orbit... and yes, these things change for Earth, too);
• plus more or less arbitrary subdivisions and other units I can't think of.

Then a galactic-scale measure of time could be:

• the time it takes for the Galaxy to fully complete one turn (you might wanna compute the average velocity of all those stars, or at least pick some reference stars to simplify the work);
• one full rotation of the Galactic core (same thing as above, as the core is also made of stars but much more densely clustered);
• one spin of the supermassive black hole that's hypothesized to occupy the center of our Galaxy (though I presume it's really fast, so it'd be more like the equivalent of a nanosecond for humans or something);
• the average time between two supernovae, the average lifetime of a star
• the time it takes for light to cross the whole Galaxy, and/or just its core
• other units I can't think of.

Finally, a measurement on the universal scale might be:

• the period of the cosmic microwave background;
• the time it takes for light to travel the average distance between two galaxies;
• other units I can't think of.

Others feel free to add to the list.

Edited November 26, 2017 by Feather Spiral