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Thread: In Case You Missed It

  1. #1
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    Default In Case You Missed It

    https://en.wikipedia.org/wiki/2019_r..._SI_base_units

    Throw out your old science textbooks...
    Once milk has been poured over corn flakes, the clock starts ticking.

  2. #2
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    ... but you can stay with your old measures

    The new definitions aim to improve the SI without changing the value of any units, ensuring continuity with existing measurements.
    Viktor
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    Being able to measure and quantify everything in reality is the foundation of all science and math.

    So it's kind-of important.

    One thing I think is a bit strange is how we use Earth based time to measure things, like a light year.

    That doesn't really make a lot of sense in the context of the entire Universe.

    Plus an Earth year is not a constant measure of time.

    But then again.... What is?

    Space-TIme itself is ever expanding.

    I guess it's all relative.
    Last edited by james; 05-20-2019 at 07:18.
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    "One thing I think is a bit strange is how we use Earth based time to measure things, like a light year.
    That doesn't really make a lot of sense in the context of the entire Universe."
    Come to think of it, you are actually right.

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    Ok. So if you get the whole e = Mc^2 thing, then a photon travels through space at c and therefore itself experiences no time.

    It's existence and travel from origin to absorption literally IS time.

    It is said that a photon takes millions of years to move from the core of The Sun to the surface before it can radiate outward to The Heliosphere.

    So what does that mean? Does a photon "experience" time?

    If a photon exists outside of time, how do we know which one is which?

    It seems to us that they begin and end.

    Do they?

    Is it possible that there is only one photon and it is in all places at "the same time" ... "all the time"?

    .
    Last edited by james; 05-20-2019 at 20:13.
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  6. #6
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    Quote Originally Posted by james View Post
    Ok. So if you get the whole e = Mc^2 thing, then a photon travels through space at c and therefore itself experiences no time.

    It's existence and travel from origin to absorption literally IS time.

    It is said that a photon takes millions of years to move from the core of The Sun to the surface before it can radiate outward to The Heliosphere.

    So what does that mean? Does a photon "experience" time?

    If a photon exists outside of time, how do we know which one is which?

    It seems to us that they begin and end.

    Do they?

    Is it possible that there is only one photon and it is in all places at "the same time" ... "all the time"?

    .
    How many times does a drunk have to bump around till he finds an exit?
    Once milk has been poured over corn flakes, the clock starts ticking.

  7. #7
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    Quote Originally Posted by james View Post
    Ok. So if you get the whole e = Mc^2 thing, then a photon travels through space at c and therefore itself experiences no time.
    Insofar as a photon can "experience" anything, yes, it should not experience any time because at the speed of light the time dilation is infinite.

    It's existence and travel from origin to absorption literally IS time.
    Well, not exactly, because time is relative. To us, because we are moving fairly slowly and are not experience any relativistic time dilation effects, the duration of the photon's "existence and travel from origin to absorption" is going to appear to be some amount of measurable time. But that is only from our reference point. From the reference point of the photon itself, that interval is zero and there is no measurable time. To put it another way: for something that spends the entirety of it's existence (from origin to absorption) moving at the speed of light, time has no real meaning.

    It is said that a photon takes millions of years to move from the core of The Sun to the surface before it can radiate outward to The Heliosphere.
    From our perspective, yes. For the photon the trip is instantaneous. Or would be, if the photon simply bounced around for millions of years. Alas, this is a flawed analogy, as the photons released during fusion are absorbed and re-emitted multiple times before a photon finally makes it out. So the photon that eventually exits is not technically the same one that was released at the core. (Not that we would be able to tell the difference of course.) Also, there are further delays introduced in this process that are not caused by the travel time but rather by the time it takes for the energy to be absorbed and re-radiated at each collision.

    If a photon exists outside of time, how do we know which one is which?
    For certain reference frames, it's impossible to tell.

    It seems to us that they begin and end.
    Do they?
    They definitely begin and end. It's just that for our reference frame the two events are separated by some measurable time period, where as from the reference frame of the photon they are instantaneous.

    Is it possible that there is only one photon and it is in all places at "the same time" ... "all the time"?
    My understanding of relativity is not good enough to refute this, even though I'm pretty sure the answer is no. Since in my reference frame I can clearly measure two separate photons (or more), if all measured photons were due to just a single photon, that would require infinite speed, which we know is impossible.

    I think the key to this is noting that "infinite time dilation" does not equate to infinite speed. But again, this is right at the limits of my understanding of relativity. It is, nonetheless, a fascinating thought experiment.

    Adam

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    Experiments with particle entanglement suggest that information or position can transmitted through space instantaneously or in no time at all.

    Earth is definitely spinning on its own axis and moving around The Sun and The Sun is moving around The Milky Way and The Milky Way is presumably moving away from The Origin of The Universe.

    So yes we are experiencing time dilation because of the total speed of our trajectory through Space-Time.

    I'm sure you have heard of the experiment with putting atomic clocks on jets and flying around The Equator in both directions.

    Is talking about photons here OT?
    Last edited by james; 05-21-2019 at 08:10.
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  9. #9
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    Wow, way back when - that's exactly what a Sister of Loretto (science teacher - Nun) told my mom in high school at the first report of the atom being "split". If you're not routinely throwing out your old science textbooks - you either are really into nostalga, just graduated. or just haven't been paying attention...

    Quote Originally Posted by dchammonds View Post
    https://en.wikipedia.org/wiki/2019_r..._SI_base_units

    Throw out your old science textbooks...
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