Direction of time

[Phi for All]

50 minutes ago, FreeWill said:

I am 999.99..9% sure that reality did not begin with the time we know. 

Then you shouldn't have claimed the BB was the first moment of reality.

 

55 minutes ago, FreeWill said:

Energy and matter are from somewhere.

Perhaps you should think about what is so dense and hot about the early universe. 

 

58 minutes ago, FreeWill said:

I think they are a consequence of a process which I expect to be the expansion of the initial inertial frame: SpaceTime. (Could we say that the resistance of spacetime is 0?).

At some point, I hope you can see how badly astray your guesswork is leading you. When you asked questions, it works out better for your knowledge. When you make things up like this, it's the opposite of doing science. 

[beecee]

13 hours ago, FreeWill said:

What are the signs of inconsistencies with the current models, of a system which has center and boundaries? I think actually everything has a physical center, if we can recognize and determine its boundaries. 

The only centers and boundaries we can logically speak of, is the center of our "observable universe"...which of course anyone can legitimately claim, from wherever he is.

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 Energy and matter are from somewhere. I think they are a consequence of a process which I expect to be the expansion of the initial inertial frame: SpaceTime. (Could we say that the resistance of spacetime is 0?) 

While knowledge and data of BB model only goes back to t+10-43 seconds, cosmologists are able to reasonably speculate re those early times. During those early times, the four forces we know of today were united in what was called the "Superforce" As space expanded and temperatures and pressures dropped, this superforce started to break up or decouple, gravity being the first. This created what we call phase transitions and false vacuums. eg: the phase transition of ice to liquid water. 

These false vacuum states may also be responsible for the Inflation epoch.

http://cse.ssl.berkeley.edu/bmendez/ay10/2002/notes/lec19.html

During this epoch as temperatures and pressures continued to drop, excesses of energy went into creating our very first fundamental particles, quarks, electrons and such. At three minutes the first atomic nucleus was formed [protons and neutrons] The rest is pretty reliable history.

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Currently, the Universe is not uniformly full of matter. Interstellar/intergalactic space vs Back whole/center of a galaxy.

The universe over large scales is homogeneous and isotropic. The same can be applied the the expansion rate...that is, it is only applied over large scales.

 

Edited May 30, 2019 by beecee

[jajrussel]

On 3/12/2019 at 6:18 AM, Razee01 said:

I don't know how it sounds, what is the direction of time? Is it towards the center of the universe, the big bang or opposite?

Thanks.

I like questions about time

I also like Swansont's answer

On 3/12/2019 at 6:45 AM, swansont said:

Unlike motion in space, where you can move in the + or - direction on a set of axes, your motion in the time dimension is only in the + direction.

We can only move in the positive direction, or I only age in the positive direction, but can I say this with absolute certainty? It depends on perspective. I am not overly fond of getting old, so from that perspective I don't exactly see getting older and a positive direction, but in relation to the Original Post when considering my age the only outcome is that I start at 0 then keep adding plusses as slowly as possible until time for me becomes a matter of 0 plusses added. This is kind of how and why questions about time relate to and belong in relativity as well as in philosophy. It is a matter of perspective

I like this answer.

On 5/30/2019 at 2:08 AM, md65536 said:

Time is like distance. (They're both measures of lengths between events)

Does this answer require a vector? Aren't vectors a matter of perspective. Generally when presented time is to the right and always on the diagonal. So from that perspective time is the diagonal. A wise man kept saying this. I foolishly kept arguing that he was wrong. Not to long ago I watched a video that made me think that if I could prove that time was vectorless  I could prove that travel back in time was impossible, but the complexity of the thought is just out if my reach. Perspective changed with each thought. Time is like acceleration it speeds up, it slows down, and for observational purposes it even stops. Someone once insisted that gravity was acceleration, or that one can't tell the difference under certain circumstances, so time is like gravity?

I have always tried to think of gravity as a positive, but then I noticed in a video that mathematically it was represented as a negative. I still haven't quite figured out exactly why, but I did notice that if -9.86etc. was entered as a positive the answer to the equation would have been the square root of a negative which kept resulting in an error message from my calculator, so apparently the answer had to be the square root of a positive number, so now I'm wondering if in order to get there should I consider that time always moves in the negative direction. Hmm, okay! What happened? Oh, I see it's a matter of perspective. The direction  one observer notes,might be seen as the exact opposite of another observers perspective. Now if I can only convince my calculator...

To the OP I'M guessing that the answer will depend on your reason for asking? I haven't read the whole thread yet so maybe you have given your reason for asking?

Anyway, I liked the question thank you for asking it. One other thing I remember about the video is that it gave an equation where time was on the right side of the equal sign. So I'm assuming that if I want to ever again ask what is time all I should have to do is flip the equation around where instead of equation=t, it becomes t=equation. Basically it was something like a negative times a negative equals the square root of a positive, so now I'm wondering if I can say time is like the square root of a positive, and is this proof that you can't go back in time?

Sorry I drifted off topic, I'm wondering why you asked the question? I should stop drifting and read the entire thread to see if you stated why you asked the question. 

[Art Man]

On 6/5/2019 at 7:46 AM, jajrussel said:

Someone once insisted that gravity was acceleration, or that one can't tell the difference under certain circumstances, so time is like gravity?

I have always tried to think of gravity as a positive, but then I noticed in a video that mathematically it was represented as a negative. I still haven't quite figured out exactly why, 

I would suppose that gravity/time is represented as a negative because the universe is decaying and time is such a basic floor level concept that it must be plugged into the mathematics to account for the decay of matter and the entropy of all existence, therefore, at the start of existence all matter was new and as time passed and the universe expanded matter was lost to decay and collisions on the atomic level.

As matter continuously accumulated into stars and planets thanks to gravity, these collisions encouraged decay.

And since to an observer the passing of time is determined by the strength of gravity and the speeds of the planets and the rotation of the sun and the effects of gravity exchanged between each of these objects, it is difficult to imagine time without thinking of gravity and the continual entropy of the universes' total mass. Since mass creates gravity one can't help but wonder does the speed of time across the universe change all at once as a sort of an overtone of an "extra effect of gravity" in addition to the Earth's gravitational effect on us?

Edited August 26, 2019 by Art Man

[michel123456]

On 5/30/2019 at 11:49 AM, Strange said:

As I understand it, the mathematics of GR requires the manifold to be differentiable (smooth and continuous everywhere). A boundary, implied by a centre, could conflict with this.

Zero. So a point has no physical existence. (Neither does an ideal, 1D, line.) It is just a mathematical abstraction.

It may be a physical abstraction but IMHO it is wrong. For anything to "exist", even if this thing is an abstraction, you need time. What the mathematician describes as a point is in fact the section of an invisible line. Because if the point is described at the beginning of the concept and continues until the end of the explanation (standing as an abstraction on the black board), it means it "existed" a few seconds, or minutes. IOW what we see as a point on the blackboard is in fact a line (the translation of a point on the time line). Since it is physically impossible to "get out of time", we should always add inherently 1 dimension (the T dimension) to anything observed or described. And not add time as a 4th dimension, as if geometry could exist "out of time". It gives the false impression that space could somehow exist without time.

[swansont]

On 8/25/2019 at 10:01 PM, Art Man said:

I would suppose that gravity/time is represented as a negative because the universe is decaying and time is such a basic floor level concept that it must be plugged into the mathematics to account for the decay of matter and the entropy of all existence, therefore, at the start of existence all matter was new and as time passed and the universe expanded matter was lost to decay and collisions on the atomic level.

As matter continuously accumulated into stars and planets thanks to gravity, these collisions encouraged decay.

Matter is generally not lost to decay (in fact, you often have more matter, by particle count, after decay), and how is it that collisions "encourage" decay? (decay being a spontaneous process)

 

On 8/25/2019 at 10:01 PM, Art Man said:

And since to an observer the passing of time is determined by the strength of gravity

It's determined by the gravitational potential, which is not the same thing

1 hour ago, michel123456 said:

It may be a physical abstraction but IMHO it is wrong. For anything to "exist", even if this thing is an abstraction, you need time. What the mathematician describes as a point is in fact the section of an invisible line. Because if the point is described at the beginning of the concept and continues until the end of the explanation (standing as an abstraction on the black board), it means it "existed" a few seconds, or minutes. IOW what we see as a point on the blackboard is in fact a line (the translation of a point on the time line). Since it is physically impossible to "get out of time", we should always add inherently 1 dimension (the T dimension) to anything observed or described. And not add time as a 4th dimension, as if geometry could exist "out of time". It gives the false impression that space could somehow exist without time.

Except it's math, and 1) math is not constrained by physical laws, and 2) one may be idealizing a case and ignoring extraneous detail (in which case, refer to 1) so this is similar to objecting to the fact that there are no frictionless surfaces in the real world; it has no effect on solving a problem using one in a problem. If you want to ignore the time dimension in thinking about a problem where it has no effect, you are free to do that. Just like how you can ignore spatial dimensions because the motion of an object is not taking place in that dimension.

[J.C.MacSwell]

5 minutes ago, swansont said:

Matter is generally not lost to decay (in fact, you often have more matter, by particle count, after decay), and how is it that collisions "encourage" decay? (decay being a spontaneous process)

Still spontaneous, but isn't fission driven by collisions, and heavy water used to make fission type/resulting collisions more likely?

[swansont]

5 minutes ago, J.C.MacSwell said:

Still spontaneous, but isn't fission driven by collisions, and heavy water used to make fission type/resulting collisions more likely?

That's an induced reaction. You absorb a neutron and that causes the fission to happen. If it's spontaneous, it has to happen (or be able to happen) without outside influences.

Fission can happen spontaneously, too (it's called spontaneous fission) but it generally has a low probability, for those materials we use in reactors.

[Strange]

2 hours ago, michel123456 said:

It may be a physical abstraction but IMHO it is wrong. For anything to "exist", even if this thing is an abstraction, you need time. 

I was just answering the question of how many dimensions a point has. Nothing to do with existence or time. (Apart from the fact that points and lines don't actually exist.)

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What the mathematician describes as a point is in fact the section of an invisible line.

Only if that section has zero length.

 

[J.C.MacSwell]

4 hours ago, swansont said:

That's an induced reaction. You absorb a neutron and that causes the fission to happen. If it's spontaneous, it has to happen (or be able to happen) without outside influences.

Fission can happen spontaneously, too (it's called spontaneous fission) but it generally has a low probability, for those materials we use in reactors.

Thanks. So spontaneous fission is that which half-lives are based on?

[swansont]

2 hours ago, J.C.MacSwell said:

Thanks. So spontaneous fission is that which half-lives are based on?

Right

[Art Man]

8 hours ago, swansont said:

Matter is generally not lost to decay (in fact, you often have more matter, by particle count, after decay), and how is it that collisions "encourage" decay? (decay being a spontaneous process)

When atom smashers are used to blow apart atoms and heavier isotopes result from those collisons the matter is pushed into a state of decay and emits radioactivity. When mass accumulates into star sizes and new suns are born natural radioactive decay begins. In the early years of the universe before stars were formed there was much less radioactive decay because everything was dust and separated particles.

[swansont]

26 minutes ago, Art Man said:

When atom smashers are used to blow apart atoms and heavier isotopes result from those collisons the matter is pushed into a state of decay and emits radioactivity.

You don’t get heavier isotopes from blowing atoms apart. 

Unstable atoms emit radiation, not radioactivity. 

26 minutes ago, Art Man said:

When mass accumulates into star sizes and new suns are born natural radioactive decay begins.

No, that’s not what starts radioactivity 

 

 

 

[Art Man]

1 hour ago, swansont said:

You don’t get heavier isotopes from blowing atoms apart. 

Unstable atoms emit radiation, not radioactivity. 

So radioactivity and radiation are not the same...

 

1 hour ago, swansont said:

No, that’s not what starts radioactivity 

The pressures of all the mass in a star creates plasma, which radiates heat under extreme gravity...

And the star decays until all fuel is expelled or reaches a critical mass, in which it becomes a black hole or a pulsar....

Edited August 30, 2019 by Art Man

[Art Man]

That's "critical density" not "critical mass".

Edited August 30, 2019 by Art Man

[swansont]

1 hour ago, Art Man said:

So radioactivity and radiation are not the same...

Radioactivity is the process. Radiation is the energetic particles emitted.

1 hour ago, Art Man said:

The pressures of all the mass in a star creates plasma, which radiates heat under extreme gravity...

And the star decays until all fuel is expelled or reaches a critical mass, in which it becomes a black hole or a pulsar....

There’s more to it, and that’s not what critical mass is. None of that is radioactive decay, though decay is one of the processes in the sequence of events in the fusion cycle from H to He

please stop, and go learn some physics.

[Art Man]

9 minutes ago, swansont said:

Radioactivity is the process. Radiation is the energetic particles emitted.

There’s more to it, and that’s not what critical mass is. None of that is radioactive decay, though decay is one of the processes in the sequence of events in the fusion cycle from H to He

please stop, and go learn some physics.

I'm not all that fascinated with physics anyway.

[Strange]

45 minutes ago, Art Man said:

I'm not all that fascinated with physics anyway.

Then I suggest you stop posting uninformed and largely incorrect statements about it.

Feel free to ask questions, but it would be better if you don't try and provide answers to other people's questions when you don't have the knowledge required to provide accurate answers.

[Art Man]

5 hours ago, Strange said:

Then I suggest you stop posting uninformed and largely incorrect statements about it.

Feel free to ask questions, but it would be better if you don't try and provide answers to other people's questions when you don't have the knowledge required to provide accurate answers.

Fair enough, I was trying to be humorous with that -1 post but didn't work out that way.

Edited August 31, 2019 by Art Man

[swansont]

!

Moderator Note

A tangent on math vs physics has been split into a new thread

https://www.scienceforums.net/topic/119998-math-v-physics-split-from-direction-of-time/

 

[The Shadow]

On 3/12/2019 at 6:18 AM, Razee01 said:

I don't know how it sounds, what is the direction of time? Is it towards the center of the universe, the big bang or opposite?

Thanks.

For my thoughts...time=rate of change. Something changed...a before and after exists. The interval between before and after is time. Seconds, minutes are meaningless since they are mankind constructed units. That is why I use the word interval.

Direction of time is mandated by Entropy and laws of physics in my opinion. It is in the direction that it must be. The leaves on the ground cannot fall upwards and reattach to the branches. That would violate Entropy and energy laws (where would the energy come from to perform the work against gravity?).

Time moves in the only direction as physical laws and pure entropy allow it to move. I understand that some notable theories allow for reverse time direction. I simply cannot support them when referenced against known laws of physics though. My brain gets tired even pondering it for more than 1 minute:(

[Strange]

5 hours ago, The Shadow said:

For my thoughts...time=rate of change. Something changed...a before and after exists. The interval between before and after is time.

Different things change at different rates. Does that mean time is variable?

And what about examples where nothing changes but time still passes? For example an isolated muon will decay after about 2 microseconds. During that period nothing happens, nothing changes but still time passes.

[The Shadow]

4 hours ago, Strange said:

Different things change at different rates. Does that mean time is variable?

And what about examples where nothing changes but time still passes? For example an isolated muon will decay after about 2 microseconds. During that period nothing happens, nothing changes but still time passes.

Time is an interval in my view. An interval can vary between observers. 

The muon example shows before and after, therefore rate of change. Time lapsed (an interval occured). Also, my understanding is a muon moves at relativistic velocities. Are you stating it can be completely static?

I hold the belief that there is always change occuring...especially on a macro scale. I believe if change did not take place, nor would time. They are codependent on each other.

The 3rd law of thermo leads some people to ponder that perhaps all atomic/molecular motion would stop if temperature was low enough. However, my understanding is even at absolute zero, some atomic activity would still take place. It seems impossible to stop time or change. 

The notion of time can sure be perplexing. 

[Strange]

38 minutes ago, The Shadow said:

The muon example shows before and after, therefore rate of change. Time lapsed (an interval occured).

There is no change while waiting for the muon to decay. Nothing happens. Nothing moves. And yet time passes.

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Also, my understanding is a muon moves at relativistic velocities. Are you stating it can be completely static?

It is completely static in its own frame of reference.

38 minutes ago, The Shadow said:

I hold the belief that there is always change occuring

This is a science forum. I don't think alone cares what you believe.

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I believe if change did not take place, nor would time. 

Again, nothing changes in the interval before the muon decays.

[Mordred]

2 hours ago, The Shadow said:

Time is an interval in my view. An interval can vary between observers. . 

This is the proper treatment but the interval is given units of length via ct