5 ms·

The way I like to think of it is like moving your hand through water in a swimming pool; the faster you try to move, the more the water (time) pushes against yo

by bArray 6y ago

The way I like to think of it is like moving your hand through water in a swimming pool; the faster you try to move, the more the water (time) pushes against you. If you don't try to move your hand at all, the water (time) has seemingly no affect on you. In this analogy the water itself is space and time is the measurement of movement resistance. Of course there are nice little things to explore with this, like moving through running water, currents (localized loops), deep water (dense space), resistance on small vs large things, etc. If we imagine on the small enough scale where we're looking at single water molecules, resistance (time) doesn't even mean too much. As long as your water is liquid, your little molecules are bouncing around in all directions, only tending towards a given direction with some probability. Otherwise each direction is near and damnit equally easy to travel in. That's my two cents anyway.

marliechiller 6y ago
that was a really cool explanation and helped me create a mental model much easier than typical analogies, thanks!
CGamesPlay 6y ago
This is an interesting analogy which might be helpful; but I don't think taking it down to an atomic level is useful, since it breaks the analogy. Time means just as much to a single atom as it does to your entire hand, the speed limit and "increase in drag" (in the context of this analogy) is the same. The hand takes more energy to accelerate than a single atom does, but that's not because of temporal dilation--it's just the normal old classical inertia.
- bArray 6y ago
  > I don't think taking it down to an atomic level is useful, > since it breaks the analogy It was simply a suggestion as to why things might start behaving weirdly at the quantum level. My understanding is that very small things seem to act as if time doesn't really have any real favoured direction. Of course the analogy is not perfect and does not measure correctly the scale of forces involved, or even how they behave at different extremes. It's just a rough and ready mental model to begin to see things in this framing.
  - drran 6y ago
    You should scale time proportionally to the scale of space. Let's call one complete orbital cycle of one thing around another thing a "year", and one spin a "day". For example, one orbital cycle of the Sun around the center of our galaxy is "galaxy year". If we measure a human body at the scale of seconds, then we can measure position of the human with precision to single digit meters. It will behave like a particle. If we measure it at the scale of days, then it will start to blur, like a quantum particle: 30% at home, 30% at work, 30% everywhere else, including the Moon. We can use probabilistic math at this scale, to describe this weird behavior. If we measure human at the scale of years, then the human body will demonstrate dynamics and predictable trajectory: home -> school -> work -> home. We can even invent a math formula, which will correctly predicts trajectory for a human at average. If we try to measure a human at the scale of galactic year, then our detector will fail completely, because humans are short living objects. When you measure your particles, you measure it at particle seconds, particle days, particle years, or at much higher scale?
    - chrisweekly 6y ago
      Thanks for this! Never thought about it this way, but it's a terrific perspective / way to frame and explain probabilistic measurements in an intuitive way.
      - fsflover 6y ago
        The difference though is that for a quantum particle, there is no "particle second" in the sense that you can't measure exactly where it is however fast you try.
        drran 6y ago
        "we can't measure it" doesn't imply "it doesn't exist". Maybe it exists, maybe not. Let's improve our tools and try again. For example, it's impossible to measure distances shorter than photon wave length using photon stream, but it's easy to do using beam splitter and interference.
ksec 6y ago
I am not sure how accurate that analogy is, ( I guess most analogy are not made to be 100% accurate anyway ) but it explains the problem or help creating the image in my metal model far better than any thing else. Thank You.
- irrational 6y ago
  The map is not the territory.
Ono-Sendai 6y ago
This is not really an accurate analogy sorry. What is really happening is that everything (atoms etc..) are made of fields in which disturbances/patterns travel at the speed of light. When an object is moving through space, the fields have to move extra far to cover the distance through space, as well as to do the usual oscillations/vibrations/movements that give timing effects. This is where time dilation comes from. It's best understood with the reflecting-mirror-as-clock thought experiment.
- bArray 6y ago
  > This is not really an accurate analogy sorry. Well of course, it's an analogy, it only needs to be roughly correct. The idea is simply to build a mental model that many people can picture. > It's best understood with the reflecting-mirror-as-clock > thought experiment. It's good, but not something that really resonates with people's first-hand experiences.
  - Ono-Sendai 6y ago
    Well I don't think it's even roughly correct. Time is not friction or resistance.
    - Ono-Sendai 6y ago
      To add to my comment: If you really want to understand relativistic time dilation, you want to understand the bouncing-light mirror-clock experiment. It's even in the article. And it's not even an analogy, it's really why moving objects run slow. You can derive the exact special relativity time dilation factor from it.
- jjgreen 6y ago
  https://xkcd.com/895/ https://xkcd.com/895/
  - Ono-Sendai 6y ago
    The thing is, in this case, the actual cause of time dilation is reasonably understandable. There's no need to go off and invent some wild analogy. But apparently the average HN reader prefers a wildly inappropriate and ungrounded analogy to putting in a little time to understand the commonly accepted reasoning behind time dilation.
appleflaxen 6y ago
ahh. let's call your spacetime water something that evokes these qualities... "ether"! (this is not meant to be substantive criticism of your idea; I just think it's funny how much this sounds like the 19th century concept of ether that was abandoned)
- bArray 6y ago
  Haha, I do like the word "ether"! I personally think of the water as space, rather than spacetime. I think time is a byproduct of space-mass interactions. I could of course be very wrong!
  - drran 6y ago
    Space in [x,y,z], spacetime is [x,y,z;t]. It's math. Space represents the physical object, which is currently named as "physical vacuum" (literally "physical emptiness", where "physical" means that emptiness is not empty). It's hard to say what is represented by spacetime in math models.
- Leszek 6y ago
  If that sounds like an "ether" to you, wait until you read about https://simple.wikipedia.org/wiki/Higgs_field https://simple.wikipedia.org/wiki/Higgs_field
  - drran 6y ago
    Do you see much difference between ether, which is presented everywhere in our Universe, and Higgs field, which is presented everywhere in our Universe? Quote from your link: «To justify giving mass to a would-be massless particle, scientists were forced to do something out of the ordinary. They assumed that vacuums (empty space) actually had energy, and that way, if a particle that we think of as massless were to enter it, the energy from the vacuum would be transferred into that particle, giving it mass.»
Zenst 6y ago
> The way I like to think of it is like moving your hand through water in a swimming pool; the faster you try to move, the more the water (time) pushes against you. If you don't try to move your hand at all, the water (time) has seemingly no affect on you. In this analogy the water itself is space and time is the measurement of movement resistance. Temporal friction!
delecti 6y ago
I find it much easier to picture in relation to the unit circle. We're always moving at the speed of light, it just depends on whether that's at 1 second per second, 300,000 km/sec, or somewhere in between. [1] https://en.wikipedia.org/wiki/Unit_circle https://en.wikipedia.org/wiki/Unit_circle

by bArray 6y ago

marliechiller 6y ago

that was a really cool explanation and helped me create a mental model much easier than typical analogies, thanks!

CGamesPlay 6y ago

This is an interesting analogy which might be helpful; but I don't think taking it down to an atomic level is useful, since it breaks the analogy. Time means just as much to a single atom as it does to your entire hand, the speed limit and "increase in drag" (in the context of this analogy) is the same. The hand takes more energy to accelerate than a single atom does, but that's not because of temporal dilation--it's just the normal old classical inertia.

bArray 6y ago
> I don't think taking it down to an atomic level is useful, > since it breaks the analogy It was simply a suggestion as to why things might start behaving weirdly at the quantum level. My understanding is that very small things seem to act as if time doesn't really have any real favoured direction. Of course the analogy is not perfect and does not measure correctly the scale of forces involved, or even how they behave at different extremes. It's just a rough and ready mental model to begin to see things in this framing.
- drran 6y ago
  You should scale time proportionally to the scale of space. Let's call one complete orbital cycle of one thing around another thing a "year", and one spin a "day". For example, one orbital cycle of the Sun around the center of our galaxy is "galaxy year". If we measure a human body at the scale of seconds, then we can measure position of the human with precision to single digit meters. It will behave like a particle. If we measure it at the scale of days, then it will start to blur, like a quantum particle: 30% at home, 30% at work, 30% everywhere else, including the Moon. We can use probabilistic math at this scale, to describe this weird behavior. If we measure human at the scale of years, then the human body will demonstrate dynamics and predictable trajectory: home -> school -> work -> home. We can even invent a math formula, which will correctly predicts trajectory for a human at average. If we try to measure a human at the scale of galactic year, then our detector will fail completely, because humans are short living objects. When you measure your particles, you measure it at particle seconds, particle days, particle years, or at much higher scale?
  - chrisweekly 6y ago
    Thanks for this! Never thought about it this way, but it's a terrific perspective / way to frame and explain probabilistic measurements in an intuitive way.
    - fsflover 6y ago
      The difference though is that for a quantum particle, there is no "particle second" in the sense that you can't measure exactly where it is however fast you try.
      - drran 6y ago
        "we can't measure it" doesn't imply "it doesn't exist". Maybe it exists, maybe not. Let's improve our tools and try again. For example, it's impossible to measure distances shorter than photon wave length using photon stream, but it's easy to do using beam splitter and interference.

ksec 6y ago

I am not sure how accurate that analogy is, ( I guess most analogy are not made to be 100% accurate anyway ) but it explains the problem or help creating the image in my metal model far better than any thing else. Thank You.

irrational 6y ago
The map is not the territory.

Ono-Sendai 6y ago

This is not really an accurate analogy sorry. What is really happening is that everything (atoms etc..) are made of fields in which disturbances/patterns travel at the speed of light. When an object is moving through space, the fields have to move extra far to cover the distance through space, as well as to do the usual oscillations/vibrations/movements that give timing effects. This is where time dilation comes from. It's best understood with the reflecting-mirror-as-clock thought experiment.

bArray 6y ago
> This is not really an accurate analogy sorry. Well of course, it's an analogy, it only needs to be roughly correct. The idea is simply to build a mental model that many people can picture. > It's best understood with the reflecting-mirror-as-clock > thought experiment. It's good, but not something that really resonates with people's first-hand experiences.
- Ono-Sendai 6y ago
  Well I don't think it's even roughly correct. Time is not friction or resistance.
  - Ono-Sendai 6y ago
    To add to my comment: If you really want to understand relativistic time dilation, you want to understand the bouncing-light mirror-clock experiment. It's even in the article. And it's not even an analogy, it's really why moving objects run slow. You can derive the exact special relativity time dilation factor from it.
jjgreen 6y ago
https://xkcd.com/895/ https://xkcd.com/895/
- Ono-Sendai 6y ago
  The thing is, in this case, the actual cause of time dilation is reasonably understandable. There's no need to go off and invent some wild analogy. But apparently the average HN reader prefers a wildly inappropriate and ungrounded analogy to putting in a little time to understand the commonly accepted reasoning behind time dilation.

appleflaxen 6y ago

ahh. let's call your spacetime water something that evokes these qualities... "ether"! (this is not meant to be substantive criticism of your idea; I just think it's funny how much this sounds like the 19th century concept of ether that was abandoned)

bArray 6y ago
Haha, I do like the word "ether"! I personally think of the water as space, rather than spacetime. I think time is a byproduct of space-mass interactions. I could of course be very wrong!
- drran 6y ago
  Space in [x,y,z], spacetime is [x,y,z;t]. It's math. Space represents the physical object, which is currently named as "physical vacuum" (literally "physical emptiness", where "physical" means that emptiness is not empty). It's hard to say what is represented by spacetime in math models.
Leszek 6y ago
If that sounds like an "ether" to you, wait until you read about https://simple.wikipedia.org/wiki/Higgs_field https://simple.wikipedia.org/wiki/Higgs_field
- drran 6y ago
  Do you see much difference between ether, which is presented everywhere in our Universe, and Higgs field, which is presented everywhere in our Universe? Quote from your link: «To justify giving mass to a would-be massless particle, scientists were forced to do something out of the ordinary. They assumed that vacuums (empty space) actually had energy, and that way, if a particle that we think of as massless were to enter it, the energy from the vacuum would be transferred into that particle, giving it mass.»

Zenst 6y ago

> The way I like to think of it is like moving your hand through water in a swimming pool; the faster you try to move, the more the water (time) pushes against you. If you don't try to move your hand at all, the water (time) has seemingly no affect on you. In this analogy the water itself is space and time is the measurement of movement resistance. Temporal friction!

delecti 6y ago

I find it much easier to picture in relation to the unit circle. We're always moving at the speed of light, it just depends on whether that's at 1 second per second, 300,000 km/sec, or somewhere in between. [1] https://en.wikipedia.org/wiki/Unit_circle https://en.wikipedia.org/wiki/Unit_circle