Can someone explain Time to me in its scientific form?

[Adam West]

I'm really confused by the whole concept and would appreciate someone explaining it to me in layman's terms.

I understand time as a unit of measure (as in a day being the time it takes for the earth to rotate once around its axis).

Is this what scientists mean when they talk about time in science terms? Maybe I'm using the wrong word terminology but let me use a what if illustration.

Just assume a human life expectancy is 90 years (I realize years is a time measurement again related to earth rotation).

Now assume, someone was flung out in outer space somewhere (it doesn't matter where) but the exact same conditions exist that would have not effect life expectancy.

Wouldn't one basically die in the same life expectancy regardless of how you do or don't measure time? Science seems to say no so I'm wondering what part about this I'm not getting. Again, is this just a technical misunderstanding as time is defined or is there something more to it?

[Mikey]

Alan Parsons explained it best

http://www.youtube.com/watch?v=nvwrSdMY7dQ

m

[Brazoo]

Time is incredibly confusing - and I don't pretend to get it all, but this what I think I get:

Time is not constant in the universe, it's relative based on variables to do mostly with how fast you are traveling in the universe and how you're effected by gravity.

So take twins, one on Earth and one traveling at a different speed through space are actually experiencing time differently. If the astronaut twin is traveling fast enough the difference in time he experiences could be significant. He could return to earth and find his brother has aged well beyond what he has aged. The astronaut twin didn't feel like he lived longer - he just lived longer relative to his earthbound brother.

If the speed and duration of time aren't significant, like if the astronaut went to the international space station for a few months, the time difference isn't significant - it exists though.

They can even measure these time fluctuations on earth. You experience time differently depending on how low or high you are. Time is slower on top of a mountain relative to how you experience time when you're at sea level - for example. People traveling in a car are experiencing time differently than people standing still.

Stephen Hawking's Illustrated Brief History of Time is good at explaining this stuff and gives lots of great examples of how this works.

This Wikipedia article seems like it might be helpful too:
Time Dilation

[Brazoo]

Of course scientists use different units of time to measure different things too - which adds to the confusion on some level. I believe that since the speed of light in a vacuum is the only theorized constant speed in the universe - so measuring time by the speed of light is the most accurate way it can be done, but those are really crazy numbers to work with.

Time can be a real brain ache even when you think you get the basics of Relativity.

[Brazoo]

Oh - duh!

This is probably the best article for you to check out:

Twin Paradox

[emeraldknight47]

Alan Parsons explained it best

http://www.youtube.com/watch?v=nvwrSdMY7dQ

m

Great, great song, my friend. And I think it offers one of the better and simplified explanations of time one could ask for. And musically, no less!

[emeraldknight47]

Regarding time, it's kind of cool and creepy at the same time to think that when you're looking up at the stars and seeing their light, you're lookng back in time at the same time, probably back to when the dinosaurs were walking around, in some cases, maybe even further.

Something to think about....!

[samurainoir]

Stephen Hawking's Illustrated Brief History of Time is good at explaining this stuff and gives lots of great examples of how this works.

Completely off topic (other than the musical video other thing posted), but you don't know how long I've been waiting for someone to come along and drop a Stephen Hawking reference.
http://www.youtube.com/watch?v=zn7-fVtT16k

[MicromanZone]

Michio Kaku has a decent explanation of the biological basis for time, internal time as well as “public” time.
Time by Michio Kaku - 2. Lifetime (2 of 4)

[megomania]

Michio Kaku has a decent explanation of the biological basis for time, internal time as well as “public” time.
Time by Michio Kaku - 2. Lifetime (2 of 4)

He's a frequent guest on Art Bell's "Somewhere in Time" and George Noory's "Coast to Coast". Always enjoy listening to him.

[The Toyroom]

Well whatever "time" is, it ISN'T always on my side...

[Brazoo]

Regarding time, it's kind of cool and creepy at the same time to think that when you're looking up at the stars and seeing their light, you're lookng back in time at the same time, probably back to when the dinosaurs were walking around, in some cases, maybe even further.

Something to think about....!

Yeah - if we're looking at a star 200 million light years away we're seeing light that left that star 200 million light years ago. (a light year meaning the distance light can travel over the period of one of our Earth years.)

So the stars we see in the sky aren't what they appear to be. They've moved from where we see them, and some have even burnt out long ago, but the light from where they are now won't be visible to us for 200 million more light years.

I think Hawking uses this example (or something like this) in "Brief History":

Let's say you're on Mars looking in a telescope at Earth and you see a murder take place. Lets say it takes 5 minutes for the light from Earth to travel to Mars. If it were possible to travel faster than light you could travel to earth and get there before the murder took place and save the person.

The laws of the universe don't permit anything traveling faster than light, but it illustrates how inconsistent time is, I think.

[Brazoo]

Michio Kaku has a decent explanation of the biological basis for time, internal time as well as “public” time.
Time by Michio Kaku - 2. Lifetime (2 of 4)

Michio Kaku is really cool - totally kooky - but really cool. He's in "How The Universe Works" as well.

[Hector]

There's really no passage of time...it's a man made concept.

[Brazoo]

People (and all life on Earth) evolved and adapted to time existing, but our sense of time or our belief in time passing isn't enough for scientists to confirm the physical existence of time for the rest of the universe.

We have to question that what we "feel" and experience isn't just a product of our place in the universe or a part of our consciousness or special to biology here on Earth - like Hector is saying.

When scientists confirm the existence of time and the direction of time they define it by looking at:

• The direction of the expansion of the universe - the universe expands from it's center, where the Big Bang took place. It's a linear direction of small to big coinciding with the direction of time.

• The way that light travels - from the past to the future - confirms that time exists.

• Entropy in the universe is always increasing. Entropy is the breaking down of everything. The dispersal of all known energy and matter over time. (The Second Law of Thermodynamics)

There may be more examples, but from what I recall these three things confirm that a linear direction exists and that time exists for the whole universe.

So time is believed to be linear, but just not constant.

(I wish I had better resources off-hand - but as far as I recall that's the general gist.)