Since what we call time is a measurement of the Earth’s rotation both around the Sun and its own axis, time is a measurement of the changing positions of physical bodies.
The changing positions of physical bodies can be classed under the broader category of change.
So time is a measure of change, the basis of which for us is constant since the time we keep is the Earth’s time because we all change with the Earth.
So since other bodies not on Earth may be changing faster or slower, their “local time” has a different speed. E.g. a comet at rest in deep space composed of solid rock will have a local time speed of close to 0.
Now don’t many physics equations assume that time is of a constant speed? Isn’t this wrong?
The problem is the equivocation, much like the problem in the GQ love thread. Time is so many things, one of which is a quantification of change. (Incidentally, the speed of the earth’s rotation is not strictly constant.) Generally, physics speaks of time as a dimension, meaning that it is nothing more than a variable in an equation. As such, it is not a constant of speed, for example, but rather is a function of it (or a relation). The relational aspect of time accounts for the relativity of physical observations.
The first blind man touched its side and hide and thought, “An elephant is big and broad, it must be like a wall.”
The second one touched the elephant’s trunk. “It is round and bends and has a mouth at the end, it must be like a snake.”
The third man touched its tusks and decided, “ An elephant is long, sharp and hard, just like a spear.”
The fourth blind man felt its leg. “How big and tall, round and firm,” he thought, “just like a tree.”
The fifth man decided after feeling the ear of the elephant, which was wide and thin and pliable. “It must be like a blanket.”
The sixth blind man touched the tail. “Why it is thin and round and flexible, an elephant is like a rope.”
Libertarian felt around, and found that the elephant was soft and squishy, and, moreover, that he was covered in it, and smelled bad. “Ah, I have it”, exclaimed Libertarian, “it’s nothing but crap!”.
I don’t believe that physicists have been able to agree on a definition of time. What we percieve as time is, indeed, phsyical changes. If everything were completely static, I guess time would have no meaning. Our perception of time relative to the sun is only one example. We perceive time by observing many, mnay different physical changes. On your hypothetical comet*, the atoms are still changing, even if nothing else appears to be doing so.
*There is no such thing as “being at rest in deep space”-- everthing appears to be at rest wrt itself. There is no origin point or preferred frame of reference from which something can be said to be “at rest”. When you see the Enterprise list after being hit with a photo torpedo, that’s a literary device. There is no set “camera” in space.
I disagree that the rate at which time passes is dependent of the amount of change occurring with in a volume of space; this is putting the cart before the horse and straying rather close to BZ0000’s insane idea that we could reverse time by reversing the direction of the Earth’s spin.
For your comet at rest in deep space, radioactive decay will still continue at the same sort of rates it would anywhwere else; the amount of discernible activity might vary from here to there, but the potential for activity is the same.
Time is not a measurement of the Earth’s rotation. Saying that time is a measurement of the Earth’s rotation is like saying distance is the measurement of miles.
Time is a measurement that uses the rotation of the Earth (and the division thereof) as a unit; just like the measurement of distance uses the “mile” as a unit.
When time is measured by a clock (which is simply based on the rotation of the Earth) it is quite constant so, no, it isn’t wrong.
I’m pleased to say that my goodbuddy the late Albert Einstein agreed with me, he said…*The distinction between past, present and future is only an illusion, however persistent.*In other words time is not only relative it is ultimately non-directional, but the logical essence of the idea “time” is progression, so therefore “time” does not exist. Unless of course there is a big clock ticking away somewhere outside of the universe.
Yes, it is not at all unreasonable to say that Time does not exist. There was a very good article about time in Sci Am several years ago that might be of interest to posters here. I don’t remember the issue, but I’m sure it’s easy to look up on-line.
Hey John Mace, I think it is not only reasonable to say that “Time” does not exist in an absolute fashion, but it is even more reasonable to consider that “time”, outside of a localized functional application, cannot exist outside of a framework of pre-conceived notions. Follow?
“it is even more reasonable to consider that “time”, outside of a localized functional application, cannot exist outside of a framework of pre-conceived notions. Follow?”
You lost me. Can you clarify the bold italicized phrase?
Time actually has its own definition now that is irrespective of the Earth’s rotation and the speed of light, since neither is constant and could change. The National Institute of Standards and Time heralds this:
“Today’s international time and frequency standards, such as NIST-F1, measure an atomic resonance of about 9 billion cycles per second. By contrast, the new NIST device monitors an optical frequency more than 100,000 times higher or about 1 quadrillion (US) cycles per second.”
This is a figure that is not likely to change, as opposed to things related to Earth’s rotation. So as far as measuring time, we’re ok.
…Time, outside of a localized functional application, cannot exist outside of a framework of pre-conceived notions.
~ milum
“You lost me. Can you clarify the bold italicized phrase?”
~ John Mace
Uh, no, John Mace. Not right now. Last night me and Jack Daniels knew. Now only Jack Daniels knows. I’ll ask him when I see him again next Saturday night.
Nothing can ever be said to be truly “at rest”. Your comet is still orbiting the galaxy and travelling with the galaxy itself with respect to other galaxies.
The measurment of time on earth does make sense but only from an earthling’s perspective as it is based upon the earth’s rotation and orbit around the sun. This constitutes a frame of reference. Pick another frame of reference, say your comet, and you might find that their clocks run at a different speed then clocks on earth (assuming the clocks are otherwise the same so as not to complicate matters).
If you like you could come up with any measurment of time you like. Something based on Wigwoos (made up) which are equivalent to 3.269859 earth seconds and is based upon the comet’s orbit of the galaxy. Doesn’t matter and doesn’t change anything.
Oops, that doesn’t work! A mile is always a mile, but if for some bizarre reason the Earth’s rotation slowed down (or reversed :)), the duration of a day would change.
As for time as atomic resonance, this is not the time we measure although it is reasuring that change continues even for my comet (should read “rock chunk”). So is there any conceivable conditions under which atomic resonance would stop?
Supposing there is, and you applied this method to an object on planet Earth, theres no molecular change happening at all to it, but its position in space is constantly changing with the Earth, and hence time still passes for it (Earth local time).
Now if you jettison it into deep space, as was pointed out by Whack-a-mole, its still changing spatially with the Galaxy due to gravity. Now supposing its still de-resonated, all you have to do is make it immune to the effects of gravity, and it will never ever change again, right? Time will truly stand still for this object!
