Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: nilak on 02/11/2016 09:54:06
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Let's imagine only the present exist. Is it possible to create a snapshot of the universe and based on that to create the next one ?
However there are some problems. In this way the snapshot will not contain velocities of entities in the universe. Also next snapshot will be difficult or impossible to define. If you are on an X axis you can chose a dx infinitesimal interval. Next snapshot will be where there is a dx change from the previous snapshot. If something was at position x, in the next snapshot it will be at x+dx. This dx, will not be possible to be measured, the same value in every reference frame, but there is one in which dx is the smallest, where time runs at the fastest rate coresponding to an infinite metric expansion which is actually outside of the universe. If you measure some entities have moved dx, then everything else will have to be stationary. This idea of does't quite work.
Suppose we can take a snapshot. If the snapshot doesn't include velocities, can we predict what will happen next ? Speed of causality is known and constant and if everything is made of waves that travel at c then we don't need the value of the speed. The only problem remains whether we can distinguish a wave traveling in the x direction from one that travels in the -x direction. Might have something to do with the spin. Can all the information in the universe be described from a single snapshot?
If we go to the spacetime concept, everything becomes static and makes more sense in explaining what time is. It is like an already recorded tape. The velocity of objects can be extracted from there. However, this doesn't explain why do we feel only the present is real ? Another question would be, is time an axis with no beginning or end like a straight line or is it a circle ? How can it be the universe an already recorded tape if the time axis is infinite? To make an analogy to time axis, if we take an x axis of space, it can be infinite, but in reality the universe seems to have a size. Beyond that size, space doesn't exist. We can question the time axis in the same way.
Another thing that results from spacetime. If you define an X and a t axis within certain limits and place a point entity with no hidden properties, the spacetime entity becomes a line within the spacetime limits. It is no longer a point. In this case the spacetime entity is the line, not the point. A complex object in space cannot preserve it's integrity in time. It constantly changes its information when you folow the time line, although it apears like the same object. For simple entities it lools like this, say we have two point particles, red and blue, in 1d space aproaching to each other, after the collision they may turn to another particle green for example. Those particles were in spacetime two lines, red and blue then they merged into one green line. The only spacetime entities are now these three lines.
Although spacetime concept integrates time as a length dimension, the time dimension is not the same as a space dimension. If you slice the time axis, all the information embedded into the 3d space is constant, but if you slice in a space x axis, the information contained in the y,z and t, is not constant. Even in a universe with only one space dimension, the same thing happens. For example we have at time t=0. on x axis two points A at x=1, and B at x=3. At time t=1, A is at x=2, B at x=3. The amount of information is constant and equal to 2 points (A and B) at their location in space axis. But when you follow the x axis, the information is not preserved anymore. At x=0 there is nothing, at x=1 the info is 1 point (A) and location 0 in time, for x=2, one point (A), and for x=3, 2 points (B), at location in time 0 and 1. Since the information is constant on the time axis, theoretically, we should be able to take single a snapshot and contain all the information in the universe. Velocity or momentum should be contained in a single snapshot, not determined between two successive positions.
These issues above are only some weid things that cand be said about the spacetime concept and it doesn't necessarily mean the concept is wrong.
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You can't take a snapshot of "the universe" that way. That would require that there be some unique time, a "now", that could be agreed upon by all observers. It would be necessary for all observers to be able to agree that the snapshot was taken simultaneously, everywhere. Special relativity requires "non-simultaneity"... for any two events that are simultaneous from the perspective of one observer there will be equally valid reference frames from which one event precedes the other and other reference frames from which the events are not simultaneous but the order reversed.
Though people occasionally tilt at the windmill of special relativity, there is no doubt that non-simultaneity is a fact.
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You can't take a snapshot of "the universe" that way. That would require that there be some unique time, a "now", that could be agreed upon by all observers. It would be necessary for all observers to be able to agree that the snapshot was taken simultaneously, everywhere. Special relativity requires "non-simultaneity"... for any two events that are simultaneous from the perspective of one observer there will be equally valid reference frames from which one event precedes the other and other reference frames from which the events are not simultaneous but the order reversed.
Though people occasionally tilt at the windmill of special relativity, there is no doubt that non-simultaneity is a fact.
Supposing we know all the rules of how the universe works and create a virtual micro version of the universe in a computer, that would start from a single snapshot, it would matter if the observers agree on the time "now". The system they described should be equivalent in a way. Whichever snapshot you use to start with, over time the system will reach the same state. Compared to a recorded tape, it would be like starting form different positions of the tape but they will show the same movie eventually. You would only miss some information in the past.
The problem is if we can theoretically take a single snapshot to describe the state or it is necessary a dt interval ? Remember the most important time dimension property is that the energy/information is conserved on the time axis.
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A different idea about time
If we look at SR basic example, instead of time dilation / space contraction , we can draw a different conclusion. The example if a relativistic train shows a beam of light sent up then received by a detector. If the train is moving, an onserver will see the same speed if the beam, that travels a longer distance. If you think of the laser / detector as a clock it will take say 1ns for 1 cycle and conclude that is time. If you go faster, you still wait for the beam to return even if it will take longer and say that is still 1 ns. An observer that is considered stationary will also measure time using the same clock. Since its beam travels a shorter path it will reach the detector sooner and will observe the clock doing that is say 2ns. Other than saying there must be some time dilation, we can conclude their clocks don't measure time. If you throw an object instead of light at the same speed relative to the observer at rest, thinking that is your clock, you will get the same result and that is definitely not time but the speed of the object (ignoring gravity and considering a perfect elastic bounce from the ceiling).
In conclusion, our clocks don't measure time as we first (newtonian absolute time) defined it. We thought it did but relativity demonatrates it doesn't.
The answer for the question why do other clocks, like atomic clocks experience time dilation, is straight forward. I consider that a coincidence would be extremely weird and unexpected, at least for me. All the clocks we use experience the same phenomenon as with the light clock. The internal causality is constant in absolute space and time but there is orbital trajectory that changes. When an object is moving faster in absolute space, it takes longer to complete a cycle we judge as being time.
In the absolute frame there seem to be no space contraction. At the contrary, fast absolute objects will appear elongated. Time dilation is not allowed by definition.
Acceleration and gravity explanation is very important for this idea to fully work.
Unfortunately the light clok doesn't work anymore in an accelerated frame. You only use the results from speed and obtain the results mathematicaly.
However if we assume a mass particle being composed of waves at the same absolute speed but having orbial trajectory the model becomes easier.
Following these conclusions I would say that after all, these waves indeed self propagate through empty but flat space. Gravity would be an attraction between energy waves. The apparent attractive force is an effect of a field created by the energy whithin the wave folowing a strict rule. Filelds interaction creates aparent forces. The more energy the more apparent mass.
The absolute frame is equivalent to a simpler frame of reference that has the highest clock rate. It may happen that no object in the universe is at rest in the absolute frame.
If we analyze the model energetically, more weird things happen. No matter the speed it travels in the absolute frame an object always has the same energy provided the waves that compose the structure remains at the same frequency (Like photons.) Conservation of energy happens because it is in fact always kinetic, obviously because they travel at the same absolute speed. Measured relatively they of course have different energies.
Black hole interpretation
In the absolute reference frame, black holes become a concentrated cocktail of waves that still travel at c. Black holes might not stop light afte all. They keep it traped circling inside otherwise it gets redshifted till it vanishes.
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Could be you're overthinking this, Nilak. May I suggest you present your main points in brief form, so that even old codgers like me will be able to get a handle on what you are actually arguing. I'm in hospital, and out of my comfort zone, which may make a difference to what I can get my head around, but I think you're saying something I want to understand.
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Could be you're overthinking this, Nilak. May I suggest you present your main points in brief form, so that even old codgers like me will be able to get a handle on what you are actually arguing. I'm in hospital, and out of my comfort zone, which may make a difference to what I can get my head around, but I think you're saying something I want to understand.
Alright, I'll try. Time was a mathematical concept invented before relativity. This concept asumed time as absolute. This means that wherever you go, whatever you do time ticks at the same rate. We then managed to build cloks that we thought can measure this absolute time. We defined a second based on some observed cyclical activity like our earth orbiting the sun. As clocks improved they were able to measure precisely what we thought it was absolute time. Special relativity deomonatrated that relative speed can make a clock tick faster or slower and we asumed time is relative. If time was relative then speed of light has to be absolute (unchanged whatever you do). However the idea is even though tick rates change it doesn't mean time changes. It can also mean clocks don't measure time. We can still keep the notion of absolute time and view clock as devices that measure something else (they in fact measure relative speed in an absolute frame if reference). Clock meaure a notion of relative time. A clock can run very close to an absolute clock if the realtive speed betweem them is small enough.
Relativity is useful in finding relative time clocks differences but it messes up the concept of simultaneity of course provided that my idea is correct.
If you look at a basic Special relativity example with the train and the light beams, the only difference between the moving frame and the stationary is the trajectory of the light. It can't be a coincidence the fact that the atomic clocks experience the same thing. Their internal cycle experiences the same trajectory change that leads to a frequency (tick rate) change.
What we see as spacetime curvature is in fact complex fundamental elements (lepton and quarks not bosons) geometry change but viewed in their classical way not as Quantum Mechanics describe them. Leptons and quarks should have variable geometry with speed and bosons shall have fixed geometry to explain my idea.
The internal rate of an object that modifies and it is what we read as time depend on speed. It is not the same thing with de Broglie associated wavelength or frequency. That frequency does not affect the cycles.
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It turns out, Timey is the first to realize our clocks don't measure true time and then SR doesn't explain Doppler Shift. In his post he is talking about standard second and about the doppler shift problem. I wanted to explain at some point that clocks don't measure absolute time but he was already saying that, I believe. If he did, I agree with what he says.
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This all sounds like the sort of thing I've been trying to get a handle on for some time. In time dilation it's the rate of change that changes, time is just the instrument we use to measure that change. This leaves us with the question: is time itself actually altered?
btw: if I remember correctly Timey is "she". Sorry Timey, I've forgotten your name, but I still find your ideas interesting.
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For an interesting comparison between differing views of time, one could do worse than read Sean Carroll's "From Eternity to Here." and Richard Muller's "Now". Having been in hospital for 3 weeks, I've had time to read both. Worth the effort.
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If you were to take a snapshot of the universe, any position in the photo, where the action speed was faster than the shutter speed, will show what is called motion blur. Motion blur results because the difference is speed is preserved, but since the photo stops time, the difference in speed is expressed as uncertainty in distance; d*/(t=0)=V (motion blur). Motion blur give one the impression of motion with time stopped.
That being said, when we look out at the universe, we don't see matter moving, but rather what we see is the light/energy that is reflecting off the matter, as the matter moves. Even if the speed of the matter is slow; rotation of a planet, the action we record is actually that of the light emitted by the object. Since our tools are made of matter and are in inertial reference, this means that the shutter speed will be slower that the action speed, since no camera shutter can move at the speed light. The result is uncertainty in distance; lose of simultaneity. It can also appear as frequency change, wth time stopped expressed as uncertainty in wavelength. In the photo below, motion blur has a vector.
(https://s-media-cache-ak0.pinimg.com/originals/4b/e7/43/4be74358037ca81284daa58c5e12c707.png)
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Yes, Puppypower, I understand your point. However the blurr increases as the time interval increases. If dt is infinitesimal you should get no blurr.
The snapshot I am taking about is in principle thus it is a mathematical, imaginary idea. For example in a 2 d space of coordinates, if t is the time axis and x is the length axis, a snapshot will mean a slice through t axis. This slice will be a line of infinitesimal dt width. It will contain umidimensional points. It is a mathematical line. The line is a unidimensional space made of unidimensional points. The idea of infnite and infinitesiamal dimensions is not very clear and it is only imagiantion. It is interesting in the 2d spacetime, time axis looks just as x axis, thus a point in spacetime contains both space and time dimensions. This seems to be only because of the mathematical construction.
I am aware of the uncertainty principle, but I think it is more of measurement problem rather than the reality itself.
SR also has problems with snapshots because there is no universally moment that can be thought as not. Here I again think it is a weakness of SR and not the reality.
Quantum mechanics also has problems with this because of the superposition principle. Thus if two identical universes were to be taken a snapshot at the same absolute time (presumably it is real) the two snapshots would be always different because of probability amplitudes techniques. However these snapshots would be equally valid. It only means the future cannot be predicted by any means but the probability of an outcome can be known for certain. These probabilities can only be verified after multiple measurements or after multiple imaginary snapshots.
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Nilak you are obviously aware that a snapshot of the Universe is a physical impossibility, but it is something that is frequently used by experts, notably by Barbour and Deutsch. That's fine as long as we always remember it's only an analogy. So is PP's motion blur, beautiful as his picture may be.
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Yes, even a snapshot of a small volume of space or of single particle is literally impossible in real life. But if we define time as absolute, we can have an idea of how it would look like. In SR this seem to be impossible since there is no absolute "now" and that might be a weak point.
Presumably absolute time can be defined and you can take a snapshot, the next one would be matter of accuracy. It is like if you think of the real number n1=10, you want to say what is the next real number, n2. That is impossible to tell. You can say it is an imaginary n2=10+dn. If these point are points on an axis you can understand what a continuous line is and you can use mathematics to answer questions.
For now I only want to see if the idea of absolute time and space can work .
If you have think of an universe made of a point and free space can you tell if it is moving or not ? If the universe is finite you can relate the position to the limits of the universe. If not, the point seem to have no definite position but is still debatable because you can start form the limited volume universe and define the position of the point and then extend the limits indefinitely and keep the position of the point in the middle for example. I didn't mention the possibility of another point, otherwise we would be tempted to give the position relative to it.
On the other hand, if free space is a real structure, each point in the structure can have a definite position in relation with other points then you can say whether something changes position or not. Since my model of space and matter says matter which represents fields creating waves in time travels the same way as light, this structure of space also makes sense.
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Nilak, you mentioned this question in relation to a theoretical high-fidelity computer-simulation of the universe. As a software developer, I'll answer this question with that perspective in mind.
Let's imagine only the present exist. Is it possible to create a snapshot of the universe and based on that to create the next one ?
However there are some problems. In this way the snapshot will not contain velocities of entities in the universe.
You may not have the velocity, but at every moment in time, you have the momentum.
Momentum seems to be a physical property of matter, just like position is. In fact, it even affect the phase-space of subatomic particles.
I believe I've read that a neutron star can have multiple neutrons at the "same position" in 3-space as long as they have different momentum, which corresponds to a different position in phase-space.
You can't take a snapshot of "the universe" that way. That would require that there be some unique time, a "now", that could be agreed upon by all observers. It would be necessary for all observers to be able to agree that the snapshot was taken simultaneously, everywhere. Special relativity requires "non-simultaneity"... for any two events that are simultaneous from the perspective of one observer there will be equally valid reference frames from which one event precedes the other and other reference frames from which the events are not simultaneous but the order reversed.
Though people occasionally tilt at the windmill of special relativity, there is no doubt that non-simultaneity is a fact.
Non-simultaneity is a fact, but it only affects events which are not in each other's light cones, and thus do not have a cause-effect relationship. (Assuming that there is no faster-than-light frame of reference, which is believed to be true).
In other words, if 2 events are within each other's light cones (and thus can have a cause-effect relationship), different observers in different frames of references might disagree about how much time transpires between the events, but they will not disagree about the order of the events.
If 2 events are outside of each other's light cones, (and thus can not have a cause-effect relationship), different observers in different frames of references might disagree about the order of the events.
So, a computer simulation would be able to take a snapshot at a certain "moment" in history. That snapshot would not represent a particular moment in time, but would instead represent a certain point on all cause-effect chains throughout the universe. This might be enough information to play the simulation forward from that point. I think it would be.
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And, theoretically, if you could capture all the information in the universe at "now" in one frame of reference, that should be enough to transform it to any frame of reference (which may no longer represent a single moment in time)
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You may not have the velocity, but at every moment in time, you have the momentum.
Momentum seems to be a physical property of matter, just like position is. In fact, it even affect the phase-space of subatomic particles.
I believe a neutron star can have multiple neutrons at the "same position" in 3-space as long as they have different momentum, which corresponds to a different position in phase-space.
Since in SR c is absolute and not space and time, momentum as a fundamental property seems to make sense. But how do you reconcile that with the gravitational effects of two parallel light beams versus antiparallel. I seem like if the photon is alone, it doesn't create any gravitational effect through space. Thus relativistic mass appears when there is a speed difference between two particles. In an universe made of a single photon through space the photon can't have a momentum because the apparent momentum is manifested between at least two objects.
If momentum is a physical property why can't we determine it for all particles and not only for photons, without using successive positions in time, or can we ?
In the other case with space and time absolute we don't need the momentum to describe one snapshot because the speed is already known (c) and according to my model all particles fundamental waves travel at the same speed. Momentum and mass become only convenient ways to describe a particle in certain situations.
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And, theoretically, if you could capture all the information in the universe at "now" in one frame of reference, that should be enough to transform it to any frame of reference (which may no longer represent a single moment in time)
I agree with that.
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Nilak;
Your idea sounds like another deterministic universe scenario. It assumes if you know the current state of the universe, you can predict its future. The problem is knowing the current state. Your current perceived image of the universe is a composite of objects at various times, ranging from a nanosecond to billions of years. That is enough reason why it can't be done. We can’t know where anything is, only where it was!
Consider the random event of a large asteroid colliding with the earth with the possible extinction of some life forms. The origin of the asteroid did not include this random event, i.e. the universe is not predetermined in any absolute sense, but allows for variations. Astronomical predictions, eclipses, comets, tides, etc., are successful primarily because they are local (solar system), and the laws regulating motion is known with a sufficient degree of accuracy.
If we introduce human free will, we get more random possibilities for variations.
Quantum physics has revealed a degree of unpredictability due to multiple states of a particle, resulting in predictions in terms of probabilities. Weather people have been doing that for years, since weather is such a complex system.
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cowlinator; #13
Momentum depends on velocity, it's the product mv. Mass is a property of matter. Velocity is a rate of change of position. Position is not a property of matter, but a relation of its position to a reference object.
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It's still interesting Android :)
You're perfectly correct though.
Maybe there is some way to make it work, more or fewer dimensions etc.
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Phyti:
It is not necessarily about making predictions or whether the universe is deterministic or not. It is whether hypothetically if you knew the values of the fileds (electromagnetic and other fields if there are) at an instant of time without knowing any particle velocity, you coud contain all the information possible about the state of the universe or momentum is crucial. My opinion is we don't need to contain momentum. QM says that even if you know that, and even if momentum is proved unnecessary you can't predict the future with certainty but you could (it doesn't say for certain but it neither excludes it) contain all the information to describe the state of the universe. I don't have a problem with QM here (the universe may not be deterministic), only with momentum or velocity vector. Consequently, vector velocity contains the arrow of time but if it is not needed then we can have the arrow of time without this vector.