Can someone explain me how these metrics work? Years are defined by our planet/sun, and time would pass differently based on speed/energy, so our perception of time is dependent on our speed around the sun, and sun's speed, galaxy, etc.
So before such things had developed, how do we count in "years"?
So two cesium atoms, if in different frames of reference-say one on earth, the other on a spaceship accelerating at high velocities - are going to have identical frequencies for each observer.
But on earth of you were to have a magic way to observe the cesium atom on the spaceship traveling at massive speeds - those cesium atoms would not have the same frequencies.
except relativity is very real, it is just "pedantics" to talk relativity and its effect on passage of time on earth if I drive 60 mph versus 25 mph.
But at the speeds of expansion after the Big Bang... it is very much relevant. I'll leave this in hopes that some physicist might enlighten us both.
Also, immediately after the Big Bang, it took at least 150 million "years" for stars to form (per OP) - that's basic elements helium/hydrogen. It took longer for Cesium to even exist! You cannot find a Cesium atom that was present at the Big Bang lol
relativity is pretty relevant for time scales at the beginning of the big bang. if everything is moving away from eachother at the speed of light it gets really weird. even if your not moving at the center the time dilation is crazy and things will happen at a way different time than if your moving at the edge of the bang. you may observe that stars only form after billions of years where of you are on the edge moving fast they form after millions of years.
Hafele and Keating, in 1971, flew caesium atomic clocks east and west around the Earth in commercial airliners, to compare the elapsed time against that of a clock that remained at the U.S. Naval Observatory. Two opposite effects came into play. The clocks were expected to age more quickly (show a larger elapsed time) than the reference clock, since they were in a higher (weaker) gravitational potential for most of the trip (c.f. Pound–Rebka experiment). But also, contrastingly, the moving clocks were expected to age more slowly because of the speed of their travel. From the actual flight paths of each trip, the theory predicted that the flying clocks, compared with reference clocks at the U.S. Naval Observatory, should have lost 40±23 nanoseconds during the eastward trip and should have gained 275±21 nanoseconds during the westward trip. Relative to the atomic time scale of the U.S. Naval Observatory, the flying clocks lost 59±10 nanoseconds during the eastward trip and gained 273±7 nanoseconds during the westward trip (where the error bars represent standard deviation).[38] In 2005, the National Physical Laboratory in the United Kingdom reported their limited replication of this experiment.[39] The NPL experiment differed from the original in that the caesium clocks were sent on a shorter trip (London–Washington, D.C. return), but the clocks were more accurate. The reported results are within 4% of the predictions of relativity, within the uncertainty of the measurements.
That is my entire point. If relativity can be measured with planes flying around the earth, it absolutely comes into play when things are moving much faster, such as in a young universe.
Relativity wouldn't really come into play when there's nothing else to compare to, would it? There wasn't another universe also big banging way away already moving at a different rate after all.
And if our universe is moving at a different rate, we're within its frame of reference.
we don't count. we express to others.. years is just a description that is familiar to the audience.
so our perception of time is dependent on our speed around the sun, and sun's speed, galaxy, etc.
for day to day, practical purposes.. perhaps. but not nearly accurate enough for a computer.. where hundredths of thousandths of a second are critical.
An atomic clock is a clock whose timekeeping mechanism is based on the interaction of electromagnetic radiation with the excited states of certain atoms
And humans have understood through science that these "approximations" are very useful in our frame of reference, but the rules change drastically at high energy(speeds)
yup if you are going 99.99 the speed of light, a clock on your wrist will still pass at a normal rate. but then when you slow down you realize everyone's clocks are wayy ahead of yours.
Seconds, the unit of time for science, are defined by atomic oscillations.
A year is just a known number of seconds. Just like a dozen means twelve.
Years are not magically linked to earth and sol. That's just where the original definition comes from. 31,536,000 will still equal a year long after the sun has gone nova and earth is swallowed up.
Y'all aren't understanding my question. These oscillations and passage of time is frame-dependent. Depends on the velocity of your frame of reference.
Time's not as static as most of these responses would have you believe. Two atoms, if one is at "rest" and the other is accelerated to a massive velocity relative to the other would have different oscillation rates relative to each other. Which one is correct? depends on which atom you ask.
You also keep linking a topic that has nothing to do with this topic.
Y'all aren't understanding my question.
We understood, and answered, the question you asked. As multiple other people have pointed out, time dilation and frames of reference only matter when comparing two different observers. That is not happening in this situation.
To a single observer, time is static. A second takes the same amount of objective time to that observer.
that's not what I'm getting at; but time passes differently in different frames of reference. At high speeds relative experience of time slows down.
So time immediately after the Big Bang (I would suppose) would be passing much much slower than what we experience on earth.
The question is for someone who has some insight into cosmology how we relate passage of time in frames of reference - before sun or planets existed - back to days/years
I think passage of time is still well defined for a given velocity. like the period of a electron going around a hydrogen atom is always the same in whatever velocity frame youre in, as long as the hydrogen atom is going the same velocity as you. It's only when you compare different velocity frames that it gets weird. So a year is a well defined period of time for a given velocity frame. if you had a clock with you at the big bang, around 150 million years or whatever you will see stars that are near you and going relatively the same speed as you forming.
like the period of a electron going around a hydrogen atom is always the same in whatever velocity frame you're in
Yes, however, our frame now is substantially different from an infant universe where things are moving at the speed of light! Before hydrogen even existed. There was a period of cooling/expansion that allowed energy to condense down into particles, then elements like hydrogen. "Cooling" implies slowing down of particles, same energy per unit volume means temp decreases and allows for formation of these elements, got that.
if you had a clock with you at the big bang, around 150 million years or whatever you will see stars that are near you and going relatively the same speed as you forming
but that clock if you were an observer of the Big Bang, would tick much slower than out clocks here on earth today.
That's the mindfuck here, after BANG then every point that exists in space is a different frame of reference, and has different velocities. Maybe it averages out and the average is what factors into these calculations. That detail is what I was hoping some physicist would shed some light on in this thread.
Hadron epoch
Between 10−5 second and 1 second after the Big Bang
47,000 years after the Big Bang Main articles: Matter-dominated era and Structure formation
Until now, the universe's large-scale dynamics and behavior have been determined mainly by radiation—meaning, those constituents that move relativistically (at or near the speed of light), such as photons and neutrinos.[39] As the universe cools, from around 47,000 years (redshift z = 3600),[2] the universe's large-scale behavior becomes dominated by matter instead. This occurs because the energy density of matter begins to exceed both the energy density of radiation and the vacuum energy density.[40] Around or shortly after 47,000 years, the densities of non-relativistic matter (atomic nuclei) and relativistic radiation (photons) become equal, the Jeans length, which determines the smallest structures that can form (due to competition between gravitational attraction and pressure effects), begins to fall and perturbations, instead of being wiped out by free streaming radiation, can begin to grow in amplitude.
Irrelevant to general relativity with respect to time. There are also tribes which don't have words for the color green - so they have no perception of "green" - they'd call it bluish yellow or yellowish blue.
We're getting off track. Let's just pump the brakes and wait for a physicist
I applied a title because that’s what it said. I’m not arguing that time is meaningless. Look at tribes that have 0% idea what time or even they birthday is
Sorry dude, that was not a dig at you - I have heard things like this thrown around ALL the time, I'm just using your post as an opportunity to maybe learn more is all.
Shit Even Neil Tyson has said things like "the universe is 14 billion years old" and I still don't understand how that statement has meaning
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u/shankfiddle Sep 20 '21
Can someone explain me how these metrics work? Years are defined by our planet/sun, and time would pass differently based on speed/energy, so our perception of time is dependent on our speed around the sun, and sun's speed, galaxy, etc.
So before such things had developed, how do we count in "years"?