How many meters is a second?

[ryan]

If the past is ultimately a 4d object, I wonder if we can measure time in meters.

We know that a 1 meter = 1 meter = 1 meter in all 3 spatial dimensions. We know this because a box 1 m^3 has the same length in all 3 directions when measured by a single meter stick.

But what about time? Is it possible to measure a second in meter units?

 

[skepticalbip]

No more possible than measuring your shoe size in coulombs.

 

[ryan]

No more possible than measuring your shoe size in coulombs.

But time is ultimately regarded as a spatial dimension.

 

[steve_bank]

Seconds and meters are now independent definitions.

Distance is in meters. Rate of change of distance is meters per secomd.

Typically s = distance in meters and time is t in seconds. v = velocity

v = s/t or meters per second.

So to answer your question the number of meters in a second depends on how fast you are going....

You can take the inverse. you are traveling 2 meters per send 2m/1s. Taking the inverse it is 1 second/2 meters or .5 seconds/meter. 6 of one half a dozen the other. Different ways to look at it.

 

[skepticalbip]

No more possible than measuring your shoe size in coulombs.

But time is ultimately regarded as a spatial dimension.

Nope. Time is a temporal dimension.

True that spacial and temporal dimensions are intimately connected but are quite different.

 

[steve_bank]

No more possible than measuring your shoe size in coulombs.

But time is ultimately regarded as a spatial dimension.

To move in space a distance dx requires a time interval dt. From relativity there is no preferd reference frame, so to define a point in space requires [x,y,z,t] relative to a reference point.

 

[ryan]

No more possible than measuring your shoe size in coulombs.

But time is ultimately regarded as a spatial dimension.

Nope. Time is a temporal dimension.

True that spacial and temporal dimensions are intimately connected but are quite different.

Time is a spatial dimension with a single direction.

 

[skepticalbip]

Nope. Time is a temporal dimension.

True that spacial and temporal dimensions are intimately connected but are quite different.

Time is a spatial dimension with a single direction.

You can repeat that as many times as you wish but you would still be wrong.

 

[ryan]

Seconds and meters are now independent definitions.

Distance is in meters. Rate of change of distance is meters per secomd.

Typically s = distance in meters and time is t in seconds. v = velocity

v = s/t or meters per second.

So to answer your question the number of meters in a second depends on how fast you are going....

You can take the inverse. you are traveling 2 meters per send 2m/1s. Taking the inverse it is 1 second/2 meters or .5 seconds/meter. 6 of one half a dozen the other. Different ways to look at it.

That's not answering the question. Imagine you want to know the ratio of a right triangle that has no end. You would simply measure the base and height at an arbitrary point on the incline. Say for every 3 meters of base the were 2 meters of height. So it's 2m per 3m. They both have a value in meters.

The universe has the temporal dimension in the same sense. 3m/s does not tell us the value of s in meter units like the triangle did.

 

[lpetrich]

Yes, it is possible. Multiply the time value by c, the speed of light in a vacuum, and one gets a distance value. After being measured for centuries, c was fixed in 1983 as 299,792,458 m/s.

Why that speed and not some other? That is because anything that travels at c will always be observed to travel at c, no matter how much one tries to catch up to it.

That is a result of the geometry of spacetime, where combined distance s in terms of space coordinates x, y, z, and time coordinate t is

s² = x² + y² + z² - (c*t)²

If s² > 0, the combined distance is still a distance, while if s² < 0, then it is a time, and if s² = 0, then it is null or lightlike.

 

[ryan]

Nope. Time is a temporal dimension.

True that spacial and temporal dimensions are intimately connected but are quite different.

Time is a spatial dimension with a single direction.

You can repeat that as many times as you wish but you would still be wrong.

Would you agree that an electron is actually a string because of the temporal dimension?

 

[ryan]

Yes, it is possible. Multiply the time value by c, the speed of light in a vacuum, and one gets a distance value. After being measured for centuries, c was fixed in 1983 as 299,792,458 m/s.

Why that speed and not some other? That is because anything that travels at c will always be observed to travel at c, no matter how much one tries to catch up to it.

That is a result of the geometry of spacetime, where combined distance s in terms of space coordinates x, y, z, and time coordinate t is

s² = x² + y² + z² - (c*t)²

If s² > 0, the combined distance is still a distance, while if s² < 0, then it is a time, and if s² = 0, then it is null or lightlike.

Interesting, but if a point particle travels in just the x direction of 400,000,000 meters in 1 second, then s² > 0, but that would be faster than light. Similarly, if it travels in the x direction for 299,792,458 meters, then s = 0. So 1 second would be 0 meters. Do I have this right?

 

[thebeave]

Nope. Time is a temporal dimension.

True that spacial and temporal dimensions are intimately connected but are quite different.

Time is a spatial dimension with a single direction.

You can repeat that as many times as you wish but you would still be wrong.

Hey, ya never know. I've heard that in galaxies, far, far away a parsec is a unit of time.

 

[steve_bank]

Seconds and meters are now independent definitions.

Distance is in meters. Rate of change of distance is meters per secomd.

Typically s = distance in meters and time is t in seconds. v = velocity

v = s/t or meters per second.

So to answer your question the number of meters in a second depends on how fast you are going....

You can take the inverse. you are traveling 2 meters per send 2m/1s. Taking the inverse it is 1 second/2 meters or .5 seconds/meter. 6 of one half a dozen the other. Different ways to look at it.

That's not answering the question. Imagine you want to know the ratio of a right triangle that has no end. You would simply measure the base and height at an arbitrary point on the incline. Say for every 3 meters of base the were 2 meters of height. So it's 2m per 3m. They both have a value in meters.

The universe has the temporal dimension in the same sense. 3m/s does not tell us the value of s in meter units like the triangle did.

It is very simple. We quantify our reality in the fundamental units in System International. Two of which are meters and seconds. Time is measured in fractional increments of a second. A simple stop watch as an example. An electronic timer does the same thing.

You can measure distance with a metical device like a ruler. or wavelengths of light. or the travel time of a radio pulse IOW RADAR. Or the travel time of an acoustic pulse SONAR.

You can not change distance without a chnge in time, time and change in position in meters are linked. That is where the term space time continuum comes from.

If you know velocity like C or the speed of sound in air you can calculate meters from time. Routine technology.

As I said meters per second and seconds per meter are inverses. If I know I am traveling 1000 meters per hour and I drive 1 hour then it is 3600 seconds/ 1000 meters or or 3.6 seconds per meter.

Knowing velocity you can say meters per second or seconds per meter. But there is no general relation that explicitly equates seconds and meters. The second is used to define a distance. Once established that length is fixed. It is converted to meter sticks. If I say something is 2 meters long it says nothing about time.

We take C in a vacuum to be a constant reference point which is why light is used to define distance. It is easy to create a standard for meter anywhere in the world or on another planet for that matter.

https://physics.nist.gov/cuu/Units/meter.html


I don't think that is what you are asking.

 

[none]

If the past is ultimately a 4d object, I wonder if we can measure time in meters.

We know that a 1 meter = 1 meter = 1 meter in all 3 spatial dimensions. We know this because a box 1 m^3 has the same length in all 3 directions when measured by a single meter stick.

But what about time? Is it possible to measure a second in meter units?

I dunno but I made the kessel run in 12 parsecs

 

[Gun Nut]

No more possible than measuring your shoe size in coulombs.

But time is ultimately regarded as a spatial dimension.

.. relative to speed, yes. "miles per hour" is speed... and in notation Mi/Hr. Distance divided by time. If we are talking about a specific speed, then we can use it for distance... thus, the "light year".

If you want to talk about it being the 4th dimension, which is fine, we can't just declare it to be a spacial dimension, just because. Our spacial domain is 3 dimensions. The 4th dimension is outside of that domain and therefore cannot be related to distance.

 

[Tinker Grey]

No more possible than measuring your shoe size in coulombs.

But time is ultimately regarded as a spatial dimension.

.. relative to speed, yes. "miles per hour" is speed... and in notation Mi/Hr. Distance divided by time. If we are talking about a specific speed, then we can use it for distance... thus, the "light year".

If you want to talk about it being the 4th dimension, which is fine, we can't just declare it to be a spacial dimension, just because. Our spacial domain is 3 dimensions. The 4th dimension is outside of that domain and therefore cannot be related to distance.

And regardless of units, there is no 'x' in 'y'. They are orthogonal. We cannot measure y in terms of x or vice versa (or z). A point might have components of space-time in its measurements, but a component has no measure in spaces orthogonal to it. There is no reason why 'y' should have similar units to 'x'. If it does, it does (space); if not, not (space v. time).

 

[steve_bank]

dimensions are distortive tags. Contrary to scifi time is not an independent reality. time and space are damsons we contruct to describe and quantify reality.

There is no 'meters' dimension nor 'seconds' dimension. Both are arbitrary units of measure. In common usage we think of them as a kind of independent reality because it is convenient. You can say time is a dimension of space because x,y,z,t are all needed to define a point in space relative to an inertial frame.

x,y,z,t are dimensions of space.

Now I keep hearing the Dr Who theme.

 

[steve_bank]

Keep in mind there coordinate systems in use other than Cartesian 3 axis. Polar and cylindrical coordinates.

 

[bilby]

Keep in mind there coordinate systems in use other than Cartesian 3 axis. Polar and cylindrical coordinates.

It doesn't matter. Whatever system you use, the minimum number of measures required to uniquely identify a location in space is three, hence 'three dimensional'. Those measures might be distances from a reference point, or angles from a reference axis, or a mixture of both; Regardless, there are always at least three numbers to uniquely describe a point in space.

To define a point in spacetime requires at least one more number, hence spacetime is 'four dimensional'.

You can't say 'time is a dimension of space', because that's false. Time is a dimension in addition to the three dimensions that are space.