# Space/TIme

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(acording to popular and accepted theories in the scientific community)

Is time a one dimensional entity?

I've heard that space is made up of length, width, depth, and time making it a four dimensional entity, But isn't time itself three dimensional, being past, present, and future? If time is three dimensional then would'nt each instance have similar but seperate attributes makeing space/time a six dimensional entity?

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(acording to popular and accepted theories in the scientific community)

Is time a one dimensional entity?

I've heard that space is made up of length, width, depth, and time making it a four dimensional entity, But isn't time itself three dimensional, being past, present, and future? If time is three dimensional then would'nt each instance have similar but seperate attributes makeing space/time a six dimensional entity?

Here are four answers. choose the one you find most edifying.

1. No.

2. Apparently not.

3. On that basis the spatial dimensions would each be three dimesional. There would be 'this point here', 'all the points below this point' and 'all the points above this point'.

4. String theory requires more dimensions - I think eleven is the most popular and most recent, but time remains IIRC as a single dimension.

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(acording to popular and accepted theories in the scientific community)

Is time a one dimensional entity?

Yes.

I've heard that space is made up of length, width, depth, and time making it a four dimensional entity, But isn't time itself three dimensional, being past, present, and future?
Past, present, and future are like behind you, at your place, and before you. That's not three dimensions in the same sense as length, width, and depth. It's only different values of depth.
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(acording to popular and accepted theories in the scientific community)

Is time a one dimensional entity?

If I ask you for your local time, now many numbers do you need to specify?

You see that it is only one.

I've heard that space is made up of length, width, depth, and time making it a four dimensional entity, But isn't time itself three dimensional, being past, present, and future? If time is three dimensional then would'nt each instance have similar but seperate attributes makeing space/time a six dimensional entity?

Now think about how many numbers are needed to specify your position on the Earth.

Lets say I want to meet you in an office somewhere. You would need to know the longitude and latitude to find the building, then you would need what floor the office is on. So I need to give you three numbers to specify where to meet you. (Or we could pick some other coordinates, but there will still be three).

In all, if I agree to meet you at the office I would need to give you four numbers. The position of the office (or at least the building) (x,y) say, what floor it is on z, and then a time t. I need to give you (x,y,z,t).

Thus, you need four numbers to specify any "event". Space-time is then said to be four dimensional.

As an aside, there are theories that are studied that have two or more "times". I don't know much about these, but a quick google will bring things up.

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• 4 weeks later...

If I ask you for your local time, now many numbers do you need to specify?

You see that it is only one.

Now think about how many numbers are needed to specify your position on the Earth.

Lets say I want to meet you in an office somewhere. You would need to know the longitude and latitude to find the building, then you would need what floor the office is on. So I need to give you three numbers to specify where to meet you. (Or we could pick some other coordinates, but there will still be three).

In all, if I agree to meet you at the office I would need to give you four numbers. The position of the office (or at least the building) (x,y) say, what floor it is on z, and then a time t. I need to give you (x,y,z,t).

Thus, you need four numbers to specify any "event". Space-time is then said to be four dimensional.

As an aside, there are theories that are studied that have two or more "times". I don't know much about these, but a quick google will bring things up.

The scenario above makes perfect scense but it is an illusion. Your voice needs to travel a distance to reach my ears. Therefore your request for me to meet you in the future came from the past. This might not seem very important as matters go here on earth but if we were traveling the heavens it would be make huge a difference. In fact it would require some very complicated math involving six dimensions of space/time.

Edited by 36grit
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Your voice needs to travel a distance to reach my ears. Therefore your request for me to meet you in the future came from the past.

Of course. This would also be true if I send you a message via electronic means or say in Morse code via a laser pulse. We could consider the idealised situation that we occupy the same point in space-time when the message is given to you.

This might not seem very important as matters go here on earth but if we were traveling the heavens it would be make huge a difference. In fact it would require some very complicated math involving six dimensions of space/time.

Anyway, I don't see why any of this distracts from the statement that we need four numbers to describe a point in space-time, once a coordinate system has been set-up. For Minkowski space-time, setting up a coordinate system is the same as picking an origin, "(0,0,0,0)".

Why six dimensions?

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Why six dimensions?

Well, when we build machines to travel around on earth, we use newtons laws of gravity to aid in their design. When we send space craft out small distances in space, we use Einsteins principles of relativity to help guide them. To travel long distances in space, in any practical manner, we'll have to build machines capable of quantum leaping. I beleive reffering to space/time in six dimensions will be impartitve. In fact, I doubt if we'll get any closer to the "dream" than we already are, until we divide, and define, these instances of time, into very real and physical entities.

Those who believe that time is only an abstact series of events should consider that time is a mechanism working in conjunction with motion that governs the speed of all sequences of events relative to one another.

Those who think that the quantum leaping of mass is imposible, might consider the possibility that we are already quantum leaping from one instant, and place, in time the next, continually.

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Take a line.

Put a point on that line.

Put another point either side of the first point.

You now have something analogous to past, present and future.

It's still a line though.

Still one dimension.

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Why six dimensions?

Well, when we build machines to travel around on earth, we use newtons laws of gravity to aid in their design. When we send space craft out small distances in space, we use Einsteins principles of relativity to help guide them. To travel long distances in space, in any practical manner, we'll have to build machines capable of quantum leaping. I beleive reffering to space/time in six dimensions will be impartitve. In fact, I doubt if we'll get any closer to the "dream" than we already are, until we divide, and define, these instances of time, into very real and physical entities.

Those who believe that time is only an abstact series of events should consider that time is a mechanism working in conjunction with motion that governs the speed of all sequences of events relative to one another.

Those who think that the quantum leaping of mass is imposible, might consider the possibility that we are already quantum leaping from one instant, and place, in time the next, continually.

So you have no idea why six dimensions?

To confuse the issue more it maybe the case that our world is best described a $(4|4)$ dimensional supermanifold! (LOL)

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36grit - all this dimensions talk. In physics, there has to be a reason to chose the number of dimensions. And it has to be backed up by the mathematics. The core reason why physicists speak of four dimensions of spacetime is because of the so-called spacetime interval.

Take two events. Each takes place at a certain point in space and certain moment in time. Per special relativity, the separation in time or time interval between the two events is not the same for two people moving with respect to each other (called time dilation). The same is true for the separation in space or space interval (distance) between the two events (called length contraction). But, and here's the key, a certain combination of the time interval and space interval called the spacetime interval is the same value for both people. In fact, the spacetime interval between two given events is the same for all people, no matter how they are (uniformly) moving.

So that's why physicists use four dimensions in relativity (one for time and three for space). Time is relative. Space is relative. But the spacetime interval is absolute. This is a great simplifying feature in a world where everything is moving with respect to everything else.

By the way, the formula is:

The square of the spacetime interval equals the difference between the square of the time interval and the square of the space interval.

So if you want to propose a different number of dimensions, you need a physics reason and the mathematics to back it up.

Edited by I ME

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