. - 08/20/01 02:53 AM
Re: TIME for a new thread, people - 08/20/01 02:38 PM
I haven't made any firm conclusions about the philosophical part of the time discussion, but hopefully I can clear up some of the physics. Specifically, the "time is a dimension" thing and "can time have momentum?"
The reason they call time a dimension is because you can get some very nice results (meaning that you can predict the motions of particles, etc., reasonably well) if you TREAT time as a dimension. (Note to philosophers: that doesn't mean it IS a dimensions, just that this is a good way of describing it.)
OK, let's start in 3 dimensions first. We write the position of a particle as (x,y,z) relative to some origin. Say the origin is the southwest corner of the room, and you are 1.67 metres tall, and you are standing 1 metre from the west wall and 3 metres from the south wall. The position of your head in (x,y,z) coordinates would be (1,3,1.67). The x-axis in this case runs west to east, and the y-axis runs south to north, and z from ground to sky. The group of three coordinates is called a position vector and is usually symbolized by r. You can transform position vectors and get velocity, acceleration, and other useful physical quantities.
Now, it turns out that if you make your position vector four components long, instead of three, where the fourth component is time, some useful properties fall out. To do this, choose a "zero" for time as well, just as you arbtrarily chose the zero for your spatial coordinate system (I mean, it could have been in the middle of the room, on the ceiling, in the northwest corner, but I chose southwest corner). Imagine yourself zeroing a timer at a given moment, and call that "zero" for this purpose. As long as you are using the same coordinate system to describe two events happening at two times t1 and t2 at positions r1 and r2, the 4-vector DISTANCE between these two events is always the same. Say you sneeze and your brother across the room claps his hands. You can describe these events using a four-vector, which includes a component describing WHEN the stuff happened.
Distance: in 3-d space, distance between two points r1 and r2 is gotten by calculating sqrt((x2-x1)^2+(y2-y1)^2+(z2-z1)^2). In other words, subtract the components of the two vectors, then square those numbers, add them up, and square root the result.
If you're thinking in 4-D now, your vector looks like this: r=(x, y, z, ict). The time is t and you need the i (square root of -1, I know it doesn't exist in real life but it's a very useful way (again) of describing things) and the c (speed of light) to make the units work out right. Follow the same procedure to get distance between two EVENTS: the formula would be sqrt((x2-x1)^2+(y2-y1)^2+(z2-z1)^2-(ct2-ct1)^2). You just square the difference between the two time components and treat it the same as the spatial components. As long as you always remember to write in the ic part, this four-vector is a very convenient tool.
NOW, we can get to momentum. You can get velocity if you take the derivative of your position four-vector with respect to "proper time". Proper time has to do with how fast you're going and allows you to convert time between yourself and a stationary observer, which is not the same thing for very large speeds, although in our everyday life those speeds are never achieved. For those who don't do calculus, the derivative is the rate of change of something. So, you take the position vector, measure the rate of change of the position vector, and you have velocity. (Makes sense, right? Imagine a car on the highway, measure its position at time t1, measure it again at time t2, the change in position divided by the change in time between t1 and t2 gives you the velocity.) Okay, then momentum is just defined as the mass of the object multiplied by the velocity; there is a scaling factor but it is the mass-velocity thing which is important. It turns out that the fourth component, which was equal to time in the position vector, becomes the speed of light in the velocity vector, and then when you calculate momentum using the velocity vector, that fourth component gives you the expression for the ENERGY of the particle, and you've all heard this one: it's equal to mc^2!
So, can time have momentum? I guess not. The four-vector describes a particle, or a point in space, and time is just one of the four components used to describe WHERE it is in space and time. You can't say that its x-component has momentum either, it's just a component. Time is no more special than the spatial coordinates (x, y, z) in this interpretation. It's just another piece of info to describe where a particle is. It's the particle itself that has momentum.
By the way, making general relativity (far more complicated than the above) and quantum mechanics to jibe is the one thing which physicists are searching for. Relativity works well on large scales, when there is lots of mass involved, and quantum mechanics works well on small scales, but during the Big Bang, you had large gravitational forces as well as very small distances...which would obviously require those two theories to co-operate. Which, as far as I know, right now isn't quite true. But hey, they're working as fast as they can, because they all want to figure it out too!
Oh my. I guess this will be my only post today. Sorry if I've bored anyone who (a) hates physics or (b) already knows all this.
The reason they call time a dimension is because you can get some very nice results (meaning that you can predict the motions of particles, etc., reasonably well) if you TREAT time as a dimension. (Note to philosophers: that doesn't mean it IS a dimensions, just that this is a good way of describing it.)
OK, let's start in 3 dimensions first. We write the position of a particle as (x,y,z) relative to some origin. Say the origin is the southwest corner of the room, and you are 1.67 metres tall, and you are standing 1 metre from the west wall and 3 metres from the south wall. The position of your head in (x,y,z) coordinates would be (1,3,1.67). The x-axis in this case runs west to east, and the y-axis runs south to north, and z from ground to sky. The group of three coordinates is called a position vector and is usually symbolized by r. You can transform position vectors and get velocity, acceleration, and other useful physical quantities.
Now, it turns out that if you make your position vector four components long, instead of three, where the fourth component is time, some useful properties fall out. To do this, choose a "zero" for time as well, just as you arbtrarily chose the zero for your spatial coordinate system (I mean, it could have been in the middle of the room, on the ceiling, in the northwest corner, but I chose southwest corner). Imagine yourself zeroing a timer at a given moment, and call that "zero" for this purpose. As long as you are using the same coordinate system to describe two events happening at two times t1 and t2 at positions r1 and r2, the 4-vector DISTANCE between these two events is always the same. Say you sneeze and your brother across the room claps his hands. You can describe these events using a four-vector, which includes a component describing WHEN the stuff happened.
Distance: in 3-d space, distance between two points r1 and r2 is gotten by calculating sqrt((x2-x1)^2+(y2-y1)^2+(z2-z1)^2). In other words, subtract the components of the two vectors, then square those numbers, add them up, and square root the result.
If you're thinking in 4-D now, your vector looks like this: r=(x, y, z, ict). The time is t and you need the i (square root of -1, I know it doesn't exist in real life but it's a very useful way (again) of describing things) and the c (speed of light) to make the units work out right. Follow the same procedure to get distance between two EVENTS: the formula would be sqrt((x2-x1)^2+(y2-y1)^2+(z2-z1)^2-(ct2-ct1)^2). You just square the difference between the two time components and treat it the same as the spatial components. As long as you always remember to write in the ic part, this four-vector is a very convenient tool.
NOW, we can get to momentum. You can get velocity if you take the derivative of your position four-vector with respect to "proper time". Proper time has to do with how fast you're going and allows you to convert time between yourself and a stationary observer, which is not the same thing for very large speeds, although in our everyday life those speeds are never achieved. For those who don't do calculus, the derivative is the rate of change of something. So, you take the position vector, measure the rate of change of the position vector, and you have velocity. (Makes sense, right? Imagine a car on the highway, measure its position at time t1, measure it again at time t2, the change in position divided by the change in time between t1 and t2 gives you the velocity.) Okay, then momentum is just defined as the mass of the object multiplied by the velocity; there is a scaling factor but it is the mass-velocity thing which is important. It turns out that the fourth component, which was equal to time in the position vector, becomes the speed of light in the velocity vector, and then when you calculate momentum using the velocity vector, that fourth component gives you the expression for the ENERGY of the particle, and you've all heard this one: it's equal to mc^2!
So, can time have momentum? I guess not. The four-vector describes a particle, or a point in space, and time is just one of the four components used to describe WHERE it is in space and time. You can't say that its x-component has momentum either, it's just a component. Time is no more special than the spatial coordinates (x, y, z) in this interpretation. It's just another piece of info to describe where a particle is. It's the particle itself that has momentum.
By the way, making general relativity (far more complicated than the above) and quantum mechanics to jibe is the one thing which physicists are searching for. Relativity works well on large scales, when there is lots of mass involved, and quantum mechanics works well on small scales, but during the Big Bang, you had large gravitational forces as well as very small distances...which would obviously require those two theories to co-operate. Which, as far as I know, right now isn't quite true. But hey, they're working as fast as they can, because they all want to figure it out too!
Oh my. I guess this will be my only post today. Sorry if I've bored anyone who (a) hates physics or (b) already knows all this.
Re: TIME for a new thread, people - 08/20/01 02:48 PM
By the way, I only took two courses which dealt with relativity, so I don't know if I can explain the WHY it works so much as HOW it works. There are also different lines of reasoning which can all get you to the same place. So please don't give me a hard time if I wasn't crystal clear; I haven't studied relativity in quite a while!
Re: TIME for a new thread, people - 08/20/01 08:22 PM
Bean--I am enraptured! You have absolutely made my day.
Thank you, thank you; a million kisses are blowing your way!
Oh, yes--I found a good def. of compactified, too.
Thank you, thank you; a million kisses are blowing your way!
Oh, yes--I found a good def. of compactified, too.
Re: the physics of time - 08/27/01 07:15 PM
Bean says time can't have momentum. but I'll take it one step farther:
"When is 'now'? Saying that 'now' is 'this instant' is going around in circles. Every instant is 'now' when it 'happens.' The point is, how do you measure the rate of moving from one instant to the next? And the answer is, you can't. What's the rate of the passage of time?''
-Gregory Benford, Timescape
well, let's see... time passes at exactly one second per second....
"When is 'now'? Saying that 'now' is 'this instant' is going around in circles. Every instant is 'now' when it 'happens.' The point is, how do you measure the rate of moving from one instant to the next? And the answer is, you can't. What's the rate of the passage of time?''
-Gregory Benford, Timescape
well, let's see... time passes at exactly one second per second....
Re: the physics of time - 08/27/01 07:19 PM
Saying that 'now' is 'this instant' is going around in circles.
... time passes at exactly one second per second....
Is there an echo in here?
... time passes at exactly one second per second....
Is there an echo in here?
Re: A note on the death digression - 08/27/01 09:05 PM
Here's a well-known Woody Allen epigram I meant to post for Max when we were in the middle of the death discussion:
I'm not afraid of dying, I just don't want to be there when it happens.--Woody Allen
I believe it's humor that keeps us sane in the face of all these mind-searing contemplations.
I'm not afraid of dying, I just don't want to be there when it happens.--Woody Allen
I believe it's humor that keeps us sane in the face of all these mind-searing contemplations.
Re: A note on the death digression - 08/27/01 10:08 PM
Then that explains Tom Robbins new book "Fierce Invalids Home From Hot Climates" It is definately humorous and one character, a South American shaman, is named Today is Tomorrow. Has anyone else out there read this book? It's easier than reading this thread
.
.
Rags' 3rd Theorem of Unreality - 08/31/01 02:47 AM
my friend Rags has this simple theory about time:
Time is basically a distance.
Rags' 4th Theorem of Unreality:
the converse (of the above) may or may not be true depending on the length of time.
Time is basically a distance.
Rags' 4th Theorem of Unreality:
the converse (of the above) may or may not be true depending on the length of time.
. - 08/31/01 03:09 AM
Re: Rags' 3rd Theorem of Unreality - 08/31/01 09:19 AM
Time is basically a distance.
The farther we look into space, the further back in time we go, so the theory makes sense on a cosmic level. It won't help me catch the bus on time though, eh.
"Men talk of killing time, while time quietly kills them."
The farther we look into space, the further back in time we go, so the theory makes sense on a cosmic level. It won't help me catch the bus on time though, eh.
"Men talk of killing time, while time quietly kills them."
Re: Rags' 3rd Theorem of Unreality - 09/01/01 01:41 AM
Perhaps time is basically an effect...aging registers time. And time only exists due to the effects that
represent it. The only tangible force here is the aging process, which happens by itself, time simply the measurement thereof.
represent it. The only tangible force here is the aging process, which happens by itself, time simply the measurement thereof.
Re: Rags' 3rd Theorem of Unreality - 09/01/01 02:39 AM
Perhaps time is basically an effect...aging registers time. And time only exists due to the effects that
represent it. The only tangible force here is the aging process, which happens by itself, time simply the measurement thereof.
Yes yes yes! That's what I've been thinking! Thank you for putting it so much better than I could!
represent it. The only tangible force here is the aging process, which happens by itself, time simply the measurement thereof.
Yes yes yes! That's what I've been thinking! Thank you for putting it so much better than I could!
Time - 09/05/01 04:41 PM
Last night the PBS show "Nova" had what was a parallel to this thread and its predecessor on "Time" (and pondering traveling forward and backward through it). Although no concrete conclusion was offered (aside from serious doubts about traveling backward being raised), this tid-bit 'forced' me to revive this thread.
I'm paraphrasing Steven Hawking...
"I won't bet money against time travel with anyone because they may have been to the future... and know better".
I'm paraphrasing Steven Hawking...
"I won't bet money against time travel with anyone because they may have been to the future... and know better".
Re: Rags' 3rd Theorem of Unreality - 09/05/01 05:49 PM
yes, time is a measurement of distance.. but its not constant.. as few as a hundred years ago, belligerentyouth was months away from me.. now, he is less than 8 hours.. even max is only 14 to 15 hours away..
It used to take 6 days(fast) to 3 weeks (slow) to travel from NY to Washington. now fast is about 3 hours, (Amtrak metro liner from Mid town NY, 34th street to Union station DC) or 6 hours (driving time, including 1 rest stop and 1 stop to refill gas tank.)
locally, we can't really (currently!) travel back in time, but who knows.. some day in the future, there might be tours back to the big bang! .
It used to take 6 days(fast) to 3 weeks (slow) to travel from NY to Washington. now fast is about 3 hours, (Amtrak metro liner from Mid town NY, 34th street to Union station DC) or 6 hours (driving time, including 1 rest stop and 1 stop to refill gas tank.)
locally, we can't really (currently!) travel back in time, but who knows.. some day in the future, there might be tours back to the big bang! .
Re: Rags' 3rd Theorem of Unreality - 09/07/01 05:18 AM
... some day in the future, there might be tours back to the big bang!
cf. The Restaurant at the End of the Universe
cf. The Restaurant at the End of the Universe
Re: Rags' 3rd Theorem of Unreality - 09/07/01 12:51 PM
cf. The Restaurant at the End of the Universe
There seems to be a hole in my junk drawer memory. Was there not some mention of a corresponding restaurant at the beginning of the universe?
There seems to be a hole in my junk drawer memory. Was there not some mention of a corresponding restaurant at the beginning of the universe?
Re: Rags' 3rd Theorem of Unreality - 09/07/01 04:09 PM
Was there not some mention of a corresponding restaurant at the beginning of the universe?
That would be the Big Bang Burger Bar.
That would be the Big Bang Burger Bar.
Re: Time - is waiting in the wings - 02/27/02 05:31 PM
I've always liked the theory that time is a purely human construct, and that in nature there is only now. Certes, as has been posited previously in this thread, time is completely subjective. We talk of the current generation as the "now" generation, incapable of planning, or at least unwilling to do so, living only for the moment. Probably every older generation has said something similar about its successor.
Yet, even though I like the idea of time being a metaphor rather than a reality, you can't help wondering if that theory holds water. Take our dog, for instance. No, please take her. She plans future actions. In the mornings she goes downstairs and waits by the door for her walk. If we look like we're not going to walk her, she has a range of actions which she carries out, not necessarily in a set sequence, to remind us of our obligations as pet owners. In fact, I'm convinced she has the number of the RSPCA and is keeping it reserve ... To plan, the planner must have a sense of time. Sure, she starts work from cues we provide, but after that, she works it through herself. She also knows when to give up. If that doesn't show a sense of time, I'm a monkey's uncle!
Okay, throw me to the lions ...
Yet, even though I like the idea of time being a metaphor rather than a reality, you can't help wondering if that theory holds water. Take our dog, for instance. No, please take her. She plans future actions. In the mornings she goes downstairs and waits by the door for her walk. If we look like we're not going to walk her, she has a range of actions which she carries out, not necessarily in a set sequence, to remind us of our obligations as pet owners. In fact, I'm convinced she has the number of the RSPCA and is keeping it reserve ... To plan, the planner must have a sense of time. Sure, she starts work from cues we provide, but after that, she works it through herself. She also knows when to give up. If that doesn't show a sense of time, I'm a monkey's uncle!
Okay, throw me to the lions ...
Re: Rags' 3rd Theorem of Unreality - 02/27/02 06:54 PM
max, what we have here is lese chronicity -- Flatlander's post was the perfect ending to this thread.
-joe (a crime against time) friday
-joe (a crime against time) friday
timely words - 02/27/02 07:01 PM
consider the word 'jiffy', as in "I'll be with you in a ~"
there are several accepted meanings of this word, in various disciplines...
a) 1/100 of a second
b) one millisecond
c) approximately(!) one nanosecond
d) indeterminate time from a few seconds to forever
http://foldoc.doc.ic.ac.uk/foldoc/foldoc.cgi?jiffy
there are several accepted meanings of this word, in various disciplines...
a) 1/100 of a second
b) one millisecond
c) approximately(!) one nanosecond
d) indeterminate time from a few seconds to forever
http://foldoc.doc.ic.ac.uk/foldoc/foldoc.cgi?jiffy
. - 02/27/02 07:50 PM
Re: Rags' 3rd Theorem of Unreality - 02/27/02 09:39 PM
> message: If you are a time traveler or alien disguised as human and or
> have the technology to travel physically through time I need your help!
>
>
> My life has been severely tampered with and cursed!!
> I have suffered tremendously and am now dying!
>
> I need to be able to:
>
> Travel back in time.
>
> Rewind my life including my age back to 4.
>
> Be able to remember what I know now so that I can prevent my life from
> being tampered with again after I go back.
>
> I am in very great danger and need this immediately!
>
> I am aware that there are many types of time travel, and that humans do
> not do well through certain types.
>
> I need as close to temporal reversion as possible, as safely as
> possible. To be able to rewind the hands of time in such a way that the
> universe of now will cease to exist.
>
> I know that there are some very powerful people out there with alien or
> government equipment capable of doing just that.
>
> If you can help me I will pay for your teleport or trip down here, Along
> with hotel stay, food and all expenses. I will pay top dollar for the
> equipment. Proof must be provided.
>
> Please be advised that any temporal device
> that you may employ must account for X, Y, and Z coordinates as well
> as the temporal location.
>
> I have a time machine now, but it has limited abilitys and is useless
> without a vortex.
>
> If you can provide information on how to create vortex generator or
> where I can get some of the blue glowing moon crystals this would also
> be helpful. I am however concerned with the high level of radiation
> these crystals give off, if you could provide a shielding or other
> crystals which give off a north polarized vortex field just as strong or
> strong enough to make a watch stop this would be great.
>
> I am aware of two types of time travel one in physical form and the
> other in energy form where a snapshot of your brain is taken using
> either the dimensional warp or an electronic device and then sends your
> consciousness back through time to part with your younger self. Please
> explain how safe and what your method involves.
>
>
>
>
> Also if you are one of the very, very, few beings with the ability to
> edit the universe PLEASE REPLY!!!
>
>
>
>
>
> Only if you have this technology and can help me exactly as mentioned
>
> please send me a (SEPARATE) email to: IneedTimeTravel@...
>
>
>
> Please do not reply if your an evil alien!
snoot
> have the technology to travel physically through time I need your help!
>
>
> My life has been severely tampered with and cursed!!
> I have suffered tremendously and am now dying!
>
> I need to be able to:
>
> Travel back in time.
>
> Rewind my life including my age back to 4.
>
> Be able to remember what I know now so that I can prevent my life from
> being tampered with again after I go back.
>
> I am in very great danger and need this immediately!
>
> I am aware that there are many types of time travel, and that humans do
> not do well through certain types.
>
> I need as close to temporal reversion as possible, as safely as
> possible. To be able to rewind the hands of time in such a way that the
> universe of now will cease to exist.
>
> I know that there are some very powerful people out there with alien or
> government equipment capable of doing just that.
>
> If you can help me I will pay for your teleport or trip down here, Along
> with hotel stay, food and all expenses. I will pay top dollar for the
> equipment. Proof must be provided.
>
> Please be advised that any temporal device
> that you may employ must account for X, Y, and Z coordinates as well
> as the temporal location.
>
> I have a time machine now, but it has limited abilitys and is useless
> without a vortex.
>
> If you can provide information on how to create vortex generator or
> where I can get some of the blue glowing moon crystals this would also
> be helpful. I am however concerned with the high level of radiation
> these crystals give off, if you could provide a shielding or other
> crystals which give off a north polarized vortex field just as strong or
> strong enough to make a watch stop this would be great.
>
> I am aware of two types of time travel one in physical form and the
> other in energy form where a snapshot of your brain is taken using
> either the dimensional warp or an electronic device and then sends your
> consciousness back through time to part with your younger self. Please
> explain how safe and what your method involves.
>
>
>
>
> Also if you are one of the very, very, few beings with the ability to
> edit the universe PLEASE REPLY!!!
>
>
>
>
>
> Only if you have this technology and can help me exactly as mentioned
>
> please send me a (SEPARATE) email to: IneedTimeTravel@...
>
>
>
> Please do not reply if your an evil alien!
snoot
Re: Theorem v Theorum - 02/27/02 10:31 PM
I wrote theorem today. It seemed Ok. Then I posted the letter and remembered it should be theorum. I was feeling pretty stupid until I saw this board.
So I googled and got both. I'm sure that I did something to do with theorums at university - did it change or is it just another of our differences?
Jo
So I googled and got both. I'm sure that I did something to do with theorums at university - did it change or is it just another of our differences?
Jo
. - 02/27/02 10:37 PM
Re:time is a measurement of distance - 02/27/02 11:17 PM
Since we're reviving an old thread I'll put my two cents in.
I once did a wagontrain that took 7 weeks to travel through Idaho, Montana and into Canada. When we were ready to go home we jumped in the van and traveled back to where we'd started in a day. It just felt weird.
When I take time to do things slower (like in a wagon) it seems I have the time. But when I don't, it seems I never have the time to get everything done. (The two hours a day I spend trying to catch up on the 1,000's of posts here have Nothing to do with it.)
I once did a wagontrain that took 7 weeks to travel through Idaho, Montana and into Canada. When we were ready to go home we jumped in the van and traveled back to where we'd started in a day. It just felt weird.
When I take time to do things slower (like in a wagon) it seems I have the time. But when I don't, it seems I never have the time to get everything done. (The two hours a day I spend trying to catch up on the 1,000's of posts here have Nothing to do with it.)
Re: Rags' 3rd Theorem of Unreality - 02/27/02 11:21 PM
the perfect ending to
this thread.
Ah! But since we all seem to agree that this is, indeed, a "timeless" AWAD thread,
then where does the thread start...................?
and where does the thread end......................?
all non-linear pixels of an extra-ordinary reality emerging/converging out of a mutual arisal as they are...-I think
this thread.
Ah! But since we all seem to agree that this is, indeed, a "timeless" AWAD thread,
then where does the thread start...................?
and where does the thread end......................?
all non-linear pixels of an extra-ordinary reality emerging/converging out of a mutual arisal as they are...
-I think
Re: Rags' 3rd Theorem of Unreality - 02/28/02 02:02 AM
and where does the thread end......................? Speaking of rags...[music notes icon] "Oh, it's the thread that never ends; it just goes on and on, my friend..." (Couldn't help it--it's so appropriate!)
Snoot, I like the way your mind works!
Snoot, I like the way your mind works!
Re: Theorem v Theorum - 02/28/02 01:15 PM
Jo, you might have said "theorum" because that's how it sounds, but it's only spelled "theorem". Googling isn't a great way to check for spellings of words, because it seems that being able to spell and having a web page are two mutually exclusive states!
Re: Rags' 3rd Theorem of Unreality - 02/28/02 05:58 PM
>then where does the thread start...................?
and where does the thread end......................?
Knot here.
and where does the thread end......................?
Knot here.
Re: Rags' 3rd Theorem of Unreality - 02/28/02 06:18 PM
Knot here.
All of us are a frayed knot.
All of us are a frayed knot.
Re: Rags' 3rd Theorem of Unreality - 02/28/02 10:00 PM
Think. What is the singular characteristic that can be ascribed to time? Right. You that said directionality are correct.
Useful as that thought construction might be, it must be said that my neo-deterministic reconstruction of the nature of existence requires that time be non-directional.
(just thought yall would like to know. -mw)
Useful as that thought construction might be, it must be said that my neo-deterministic reconstruction of the nature of existence requires that time be non-directional.
(just thought yall would like to know. -mw)
Re: Theorem v Theorum - 03/01/02 02:20 PM
I was clearly having a brainstorm. I haven't written the word in twenty years - must have been a senior moment - glad I was right the first time!