[IzzieC (OP)]

David wants to know:

What is the definition of "Zero Time"?

Can you help?

[Colin2B]

If you mean in the phrase "in zero time" then it means in no time at all, it took no time. It's a figure of speech.

Physics can use time t=0 to denote the point at which we start measuring a process eg start of a race.
We can also refer to an infinitessimally small time ie one that is too small to be measured, or as the time interval approaches zero.

[unstman]

To answer my own question...

 I do not think the laws of nature would allow this to happen because ' zero time ' would never exist if the other dimensions are also dependant on the movement of time itself. Movement being based on the other 3 dimensions to inter-act with the 1 dimension of time. How would you be able, as an observer, to measure zero time if it did not have an adverse affect on you directly? Would zero time put you into another Universe, and how could you measure this? Zero Time would not create any paradox or conflict within a given plain of existence, as this existence would be none existing regardless whether time was still or moving around you.

Can zero time only be based on the movement of matter and nothing else? Are the 3 dimensions of matter still in existence if time was set to zero? Does energy have a zero state?

[evan_au]

What is 'Zero Time'?

The ancient Greek philosopher Zeno also struggled with this.
See: https://en.wikipedia.org/wiki/Zeno%27s_paradoxes

Today, we do have mathematical answers for things that Zeno thought were impossible:
- The Greeks didn't really believe that 0 was a real number
- They didn't really believe that a number could be negative (but somehow they still managed to do accounting!)
- The Greeks didn't think that an infinite number of really small things could add up to a finite answer
- We now know that these views are mistaken - although it took around 2,000 years for Newton and Liebnitz to demonstrated differentiation!

Can you have a change that happens in Zero time?
- It depends on whether the thing you are monitoring has a "finite first derivative with respect to time"
- So if you shoot an arrow into the air (one of Zeno's examples), the arrow height vs time follows a parabola. A parabola (a function of t²) has a finite derivative (a function of t), and so it makes sense to talk of the height and velocity at a given point in time.
- If the athlete Achilles races a tortoise (another of Zeno's examples), the distance between achilles and the tortoise is a decreasing, continuous function of time. It does decrease to zero, and does go negative (Achilles passes the tortoise in a finite time)

See: https://en.wikipedia.org/wiki/Differential_calculus

[unstman]

I guess the nearest we would get to what may be perceived as ' zero time ' is taking a picture with a camera, and the time determined by the shutter speed and to a degree exposure of light. It would not be zero time exactly, but it could be representative of capturing a 2 dimensional record of light.

However, to contradict myself, taking a picture of ' zero time ' would be impossible to do, as the light itself would require to travel from the point of light source to the camera lense, and this would involve time, thus it would not be possible to gain any information.

I would go as far as to say ' zero time ' would be equal to no light at all, in other words, complete darkness (dark matter?) whatever this is in itself?

[Colin2B]

However, to contradict myself, taking a picture of ' zero time ' would be impossible to do, as the light itself would require to travel from the point of light source to the camera lense, and this would involve time, thus it would not be possible to gain any information.

The travel time for light isn’t a problem. Imaging a series of flashes from a light source spaced 1s apart. If it takes 10min for the light to reach you what you see is a series of flashes 1s apart, it’s just that you see them 10min after they left the source.
However, as you say a photograph with a shutter speed of 0s wouldnt record anything.

One place we can see 0 time is at the apex of a curve eg the arrow fired into the air mentioned by @evan_au . The arrow spends 0 time at the top of it’s flight changing from going up to going down. The same thing happens with a child’s swing or pendulum, they spend 0 time at the turnaround point.

[alancalverd]

Mathematically, we distinguish between a point, which has zero length and no direction, and an infinitesimal line which has a direction but whose length is too small to measure. Same with time: t = 0 is a point on the time axis, δt → 0 is an infinitesimal period of time.

[jeffreyH]

If we imagine time being stopped then we can think of what that implies. All particles will be in a fixed position. All frames of reference would appear to be identical. This is whether inertial or non inertial. Relativity would not exist in this freeze frame. Once time was moving again then the postulates of relativity would apply again. In the frozen moment quantum mechanics and general relativity are indistinguishable. Now there has to be some mileage in that.

[Colin2B]

Now there has to be some mileage in that.

Not if nothing’s moving 

[jeffreyH]

Let me expand on the point. If we zoom in enough on the surface of a sphere we end up with a region that looks like a portion of a flat plane and we have in effect removed the curvature of the space. If we measure smaller and smaller increments of time we could eventually eliminate the dilation of time. When considering high and low energy domains we are at different ends of a spectrum. By removing the curvatures in space and time we may get a new insight.

[geordief]

Let me expand on the point. If we zoom in enough on the surface of a sphere we end up with a region that looks like a portion of a flat plane and we have in effect removed the curvature of the space. If we measure smaller and smaller increments of time we could eventually eliminate the dilation of time.

Does that not  simply illustrate (in the model) how time proceeds at I second per second for the observer in his /her immediate environment?

[yor_on]

Zero time covers everything

[yor_on]

You live, and so you find a clock.

[JMLCarter]

Being able to discuss theoretical or philosophical mathematical meaning of zero time is a different matter from making a physical measurement of it.
An physical example of zero time is the time that elapses in a photon's frame of reference as it propagates through a true vacuum. A possible problem with that example is that there is no such thing as a true vacuum due to a ubiquitous quantum foam of virtual particles.

[yor_on]

zero time is the start from where I'm counting in a equation
Or it is what it's all about