# How would you adapt the laws of physics for two dimensions of time?

#### greswd

So imagine there are now two dimensions of time, instead of the one dimension which we're used to.

The laws of physics which we're used to won't make anymore sense unless they're adapted for the two dimensions of time.

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#### phinds

Gold Member
I wouldn't even try since once you invoke magic, all bets are off.

#### greswd

I wouldn't even try since once you invoke magic, all bets are off.
A second dimension of time is still pretty concrete and structured, its not Harry Potter hocus pocus

there are many scientific articles about why it was likely for us to end up in a 3+1 universe

#### jedishrfu

Mentor
There is a Wikipedia topic on this issue:

Where it mentions some recent work in physics on the notion and what it would mean in the context of string theory and testability.

If you were writing some sci-fi story you could perhaps postulate that in a one time dimensional universe you have a deterministic view of things but in a two time dimensioned universe there is some indeterminacy and unpredictability as to how things age. As an example, in a sci-fi story a clock might tick fast then slow then fast again or backwards then forwards but on average over longer periods it correctly marks time just not during short durations.

#### some bloke

I'm new to the concept of a second time dimension, what will it affect? Is it like the difference between a 2 dimensional line and a 3 dimensional vector? IE, our time is a line, whereas a 2-time dimensional space would have time going in 2 "directions", at "right angles" to one another, allowing an entity to travel through 2 timelines simultaneously but at different rates? If so, will it be the entities own time compared with the time of everything around them? EG, if a radioactive isotope were to travel normally on its own timeline but at half pace to the other timeline, it would degrade at half speed to observers on timeline 2, but would itself observe everything else at double speed.
Alternatively it could be down to the aging of the entity, and so an entity travelling exclusively on one timeline would appear immortal to those on the other timeline. Could explain Elves...
if a "normal" entity were to travel equally on both timelines (describing a 45° angle through time), how would it see an entity who is confined to one timeline? in theory, 2 entities on entirely separate timelines would never meet, but one who travels both would be able to see both. I suspect that this is more in the realm of separate dimensions with interdimensional beings than the right track... so Apologies if this has been a meaningless ramble!

#### greswd

I'm new to the concept of a second time dimension, what will it affect? Is it like the difference between a 2 dimensional line and a 3 dimensional vector? IE, our time is a line, whereas a 2-time dimensional space would have time going in 2 "directions", at "right angles" to one another, allowing an entity to travel through 2 timelines simultaneously but at different rates? If so, will it be the entities own time compared with the time of everything around them? EG, if a radioactive isotope were to travel normally on its own timeline but at half pace to the other timeline, it would degrade at half speed to observers on timeline 2, but would itself observe everything else at double speed.
Alternatively it could be down to the aging of the entity, and so an entity travelling exclusively on one timeline would appear immortal to those on the other timeline. Could explain Elves...
if a "normal" entity were to travel equally on both timelines (describing a 45° angle through time), how would it see an entity who is confined to one timeline? in theory, 2 entities on entirely separate timelines would never meet, but one who travels both would be able to see both. I suspect that this is more in the realm of separate dimensions with interdimensional beings than the right track... so Apologies if this has been a meaningless ramble!
the kinematic part you've mostly nailed, its easy to conceive.

but for forces, the equations of forces, those must be adapted to two dimensions of time in order to describe this alternate universe.

#### fresh_42

Mentor
2018 Award
I think the most fundamental principle in physics is the least action. I would first try to figure out what this would be in such a model.

#### some bloke

I would suspect that this would boil down to taking any equation which is related to time and creating 2 equations and combine them to create the resultant, in the same way as you would find the resultant force of 2 force vectors.

The only way a second dimension of time would be perceptible would be if there were entities or objects/matter which utilise both timelines. A timeline running "perpendicular" to your own would be imperceptible.

Polarisation could be a useful "technobabble" solution to this. Think (abstractly) of the timelines as polarised light, at 90° to one another. if you have a perfect polarising filter in line with light A, light B is utterly blocked. but, if it is at 45°, then an element of both lights comes through. As such, if a scientist were to find a way to put a sensor at a different "angle" to time, and found that the "intensity" of the time was more than anticipated, then this would suggest another dimension of time, which is beginning to be detected as the detection of the known dimension of time is reduced.

Still on polarisation, think of how you would test if light is polarised - you hold a polarising filter in front of it and rotate it, measuring the intensity of the light which comes through. If the light isn't polarised, it won't vary much (if at all). if there are 2 beams of light, polarised at 90° to one another, it won't change much either, though if the lights were different colours it would change colour as it rotated. If the light is polarised, it will reduce to 0% and back to 100% over a 180° rotation of the filter.
So, if you had a method of rotating a filter through time, and it came back showing no change as it rotated, then it would imply that there is a second dimension of time, and time flows as a factor of both.

You could probably even link speed to theother dimension of time. If you think of it as a graph, have your current time as the line, and your speed as the gradient, and this would (sort of, in a loose way) tie into relativity, as your speed increases, you travel through the other dimension of time more than your own, and so the journey takes less time for you than it did for the "stationary" universe in which you are physically travelling.

Hope this helps!

#### Gigaz

What makes and breaks time is the ordering of events into past, present and future. An ordering relation only exists in 1D space. A two-dimensional time would therefore be hardly recognizable as the thing we call "time".

#### some bloke

I suppose a logical step is to ask how we perceive and measure time. I would argue that it comes down to movement. If nothing moves, then there is no way to measure if time is passing. I'm talking in an overall scale, not that stationary objects are not subject to time! Every clock, that I'm aware of, uses movement to measure time - whether it's a pendulum or radioactive decay, something has to move to allow time to be perceived.

Unrelated to previous statement:
For past, present & future to still make sense, the timeline of reality would have to travel at 45° between the two. Individuals could be able to veer off of the timeline to the point where they are travelling in line with one of the axes, but never past parallel. This means that, if an individual were to travel perpendicular to one dimension of time, they would not be travelling on the other. To return to normal time, they would have to travel back perpendicular to the other dimension of time. This means that their timeline will have been longer than that of those on the regular timeline. In theory, having 2 dimensions of time could simply allow the ability to slow down time without having to move at relativistic speeds. It depends if reality is travelling through both dimensions of time, or just one. Also, the idea of linear dimensions is only useful as a model, and are represented as 3 directions in which the other 2 count for nothing. This would have to be true of a second dimension for time, or there would be no need to describe it as a second dimension. As time isn't a physical thing to visualise, it is very difficult to work out what the implications of a second (or more) dimension of it would be.

Thinking of 2 entities, each travelling through the 2 dimensions of time, they would have to share reality - their physical existence must be in the same place as each other.

Assuming this dates back to the big bang, where time began, and that 2 universes started up at exactly the same time, but in different directions of time. Lets call them universe A and universe B.
in Universe A, the matter for universe A travels outwards and expands & cools to create the universe, but the matter for universe B stays put, as it has no time thus no movement. Meaning there is a singularity in the middle, which never ages, and a universe around it. Ditto but reversed in universe B.
If you travelled at "45°" to the timelines, you would see both the universes exist together. but would they interfere with one another? no amount of speed or force in the X dimension affects the speed or force in the Y dimension, so would the existence of 2 planets in the same location, both of which, to the other, doesn't exist, because it hasn't existed yet, affect each other?
In an arm-waving way this could explain black holes, as locations where time "turns" from one dimension to the other. No light escapes because, from universe A's point of view, it's frozen in time.

I think this comes in as the same level of confusing (If not more) as Relativity. 2 rockets fly away from earth in opposite directions, both see their own timeline as going slower than the other rocket, but earth sees the two rockets as having the same timeline. In this instance, the observer is earth and the 2 rockets are the 2 universes.... ...I think...

#### Tghu Verd

@greswd, what narrative are you constructing that needs two times? Knowing that, you get to describe your little universe however you like. Basically, if you are writing science fiction, then if your "laws" are consistently applied, reasonably well described for the purpose of the story, and not arbitrarily expanded upon for the purpose of the plot (like superhero characters, magical or augmented, who suddenly have new and better abilities to counter each new threat or situation that would otherwise kill them) you'll do fine.

Your are writing sci-fi, not a physics text book. Two times has no correlation to any universe we experience, so grab hold of whatever mechanism you feel comfortable describing, throw in a bit of handwavium, and get on with the story!

"How would you adapt the laws of physics for two dimensions of time?"

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