Questions about Time

[Mordred]

yes supersymmetry includes time.

 

How can you have anti-time?

[Strange]

Does super-symmetry include time?

 

 

Yes, it just describes a set of particles beyond the standard model.

 

 

Does anti-time flow "backwards"?

 

What is "anti-time"?

[AbstractDreamer]

No idea

sorry baseless assertion.

 

But if anti matter exists, and this stuff changes, how do you measure the rate of this change?

[Strange]

But if anti matter exists, and this stuff changes, how do you measure the rate of this change?

 

 

By "stuff" do you mean antimatter?

 

If so, it is measured in the same way as matter - it behaves (almost) identically to matter. The challenge is that we normally only have access to tiny amounts of antimatter so measuring its properties can be tricky. There is an ongoing project at CERN to capture enough anti hydrogen to confirm that it responds to gravity in the same way awn normal hydrogen

[AbstractDreamer]

But if super symmetry includes time, what is it's opposite?

Edited November 18, 2016 by AbstractDreamer

[Strange]

But if super symmetry includes time, what is it's opposite?

 

 

Why would it need an opposite? What is the opposite of length?

[AbstractDreamer]

baseless assertion:

 

anti length?

 

I thought by definition, symmetry means

 

the quality of being made up of exactly similar parts facing each other or around an axis.

 

If time is super symmetric, and time has an axis, am i wrong in concluding that there is negative (anti) time?

 

What is the other part that is facing time, in the symmetry of time?

Edited November 18, 2016 by AbstractDreamer

[Strange]

I thought by definition, symmetry means

 

the quality of being made up of exactly similar parts facing each other or around an axis.

 

That is just one type of symmetry.

Symmetry in mathematics is much more general (and complex) than that.

 

And supersymmetry has a very specific meaning; it describes each currently known particle being paired with a "super-partner". So each boson would have a corresponding fermion and vice versa. Nothing about anti-time.

Edited November 19, 2016 by Strange

[AbstractDreamer]

Forgive my ignorance, I haven't looked into super symmetry yet. I was blurting out thoughts.

 

Can i ask how super symmetry includes time, but that time is not symmetric?

 

I'm sure the answer probably cant be explained in English.

[Strange]

Can i ask how super symmetry includes time, but that time is not symmetric?

 

Pretty much the same way as the rest of physics.

 

(In what way is time not symmetrical?)

[AbstractDreamer]

because it has no direction? you cant go backwards? can you?

[AbstractDreamer]

So reversible time invariance? whats that?

 

Does that mean some classical physics can be mathematically performed backwards and forwards in time without changing the results?

 

Wouldn't that indicate that at least time is mathematically directional? Or rather mathematically, time can be negative?

 

I have argued on another thread against the validity of mathematics being any real, and now I'm hypocritically for its validity.

Edited November 19, 2016 by AbstractDreamer

[swansont]

You can use negative values of time; in some equations the choice of zero is arbitrary (though wisdom indicates some choices for zero are better than others for calculations)

 

In simple systems the direction of time can't be inferred from what's happening. A simple collision of two objects looks the same with time running backwards. There are no complications (like internal energy states or a third particle) to have to worry about entropy.

[AbstractDreamer]

Ah a little progress!

 

So, negative values of times can be used mathematically in certain simple collisions?

 

But only because the collision "looks" the same "playing the tape forwards" as it does in "rewind".

 

If i understood that correctly.

 

Still far from saying that negative time really exists, or that it has direction, only that in some circumstances it doesn't make difference to the description of the collision.

[AbstractDreamer]

In layman's terms, what is retro-causality?

[AbstractDreamer]

https://en.wikipedia.org/wiki/Retrocausality

 

"Feynman, and earlier Stueckelberg, proposed an interpretation of the positron as an electron moving backward in time,^[16] reinterpreting the negative-energy solutions of the Dirac equation. Electrons moving backward in time would have a positive electric charge. "

 

"The backwards in time point of view is nowadays accepted as completely equivalent to other pictures"

 

im guessing the other pictures include Dirac's Hole Theory

 

This is like anti-time i was referring to in #50. Only previously it was a baseless assertion! There is support now!

 

Does anti-time flow "backwards"?

Edited December 3, 2016 by AbstractDreamer

[Strange]

In layman's terms, what is retro-causality?

 

 

This is quite a good article: https://aeon.co/essays/can-retrocausality-solve-the-puzzle-of-action-at-a-distance

[AbstractDreamer]

So does retrocausality preserve free will?

 

But if you extrapolate this idea, the state of today is determined influenced by choices in the future? Is that not retro-superdeterminism?

 

Does the alternative action-at-a-distance imply "magic"?

 

I'm not sure which is more worrying.

Edited December 5, 2016 by AbstractDreamer

[imatfaal]

So does retrocausality preserve free will?

 

But if you extrapolate this idea, the state of today is determined influenced by choices in the future? Is that not retro-superdeterminism?

 

Does the alternative action-at-a-distance imply "magic"?

 

I'm not sure which is more worrying.

 

I think you are crossing the line into philosophy. Free will is not agreed upon, either existentially or definitionally, by most disputants in this area.

[AbstractDreamer]

Will time ever end?

 

If the universe continues to expand and entropy, will it ever reach a state where it can "decay" no further. A moment when no further change can happen. When everything has cooled to absolute zero. When all particles have decayed to sub-particles that do not experience time. Where space has expanded so much that there is no other particle within every particle's future event horizon?

 

How does expansion and entropy fit with laws of conservation of energy? Does the Universe have an absolute Energy value?

 

Can time spontaneously begin after it has stopped?

Edited December 7, 2016 by AbstractDreamer

[Mordred]

Well you will never reach absolute zero according to QM as the Heisenburg principle will always be there. According to QM the lowest possible state is zero point energy

 

https://en.m.wikipedia.org/wiki/Zero-point_energy

 

Though the heat death is a likely scenario with the current expansion and cosmological constant (assuming it remains constant in the future)

Edited December 7, 2016 by Mordred

[AbstractDreamer]

But if there is nothing within a particle's future event horizon, then uncertainty (of position and velocity) is meaningless as there is no reference, nor will there ever be a reference. The only reference would be in the past.

Edited December 7, 2016 by AbstractDreamer

[Mordred]

Quantum fluctuations don't require observers. Neither does the Heisenburg uncertainty principle. Much like time dilation occurs even if you have no observers.

 

"in fact proved later by Weyl [4], Kennard [3], and Robertson [2] - refers not to the precision and disturbance of a measurement, but to the uncertainties intrinsic in the quantum state"

 

https://arxiv.org/abs/1208.0034v2

Edited December 7, 2016 by Mordred

[AbstractDreamer]

So as space expands, does the sum total of zero-point energy increase, or are quantum fluctuations "co-thingy" with expansion.

 

"co-volumetric"?

Edited December 7, 2016 by AbstractDreamer

[Mordred]

quantum fluctuations are in essence a result of field fluctuations in QFT treatment. A field can have a measured zero energy but that is the average energy of the field. Localized regions of a field will still have fluctuations even when the average field energy is zero.

 

The Heisenburg uncertainty principle is intrinsic to field's as well. Its more often called vacuum state but it amounts to the same

Edited December 7, 2016 by Mordred