Spacetime

Okabe Rintarou

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First, a few videos to introduce a few basic concepts: If you are uncomfortable with counter-intuitive ideas (such as the idea that force is nothing but an illusion), these videos could be valuable to you:-

 

Okabe Rintarou

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Two important but mindbending experiments that make you think of conspiracies where there are none. Clears a lot of concepts:-
1.) Single particle Double slit experiment: When a single electron is fired through a double slit, it lands at a random spot on the screen on the other side of the double slits. But when this experiment is repeated multiple times (with electrons being fired one by one and the location of their fall on the screen being recorded each time), we see that the electrons that fell on the screen form an interference pattern on it. How the heck? Does that mean that an electron passing through the slit knows exactly where (and interferes with) all past electrons (which passed through the slit in the past) and all future electrons (which will pass through the slit in the future) that landed/will land and therefore does it now know where it needs to land such that the end result of it all is a set interference pattern? If not, then how do you explain why sequentially fired electrons still interfere and form a set pattern on the screen on the other side of the slits? Answers are in the video:-




2.) Delayed Choice Quantum Eraser experiment: If in the previous experiment, we try to observe which one of the two slits each of the electrons passes through, the pattern that was forming on the screen suddenly changes. Instead of a pattern, the shape of the two slits forms on the screen (i.e. all electrons fall on the screen so as to form an image of the two slits themselves, instead of an interference pattern). Its as if the electrons suddenly knew that they were being observed! And so the electrons decided to not land on the screen in a pattern, but instead land on the screen to form the shape of the two slits! Its as if either the electrons themselves were conscious, or some conscious being was manipulating each electron to behave in a certain way based on whether we were observing the electrons or not.

Now, if we create a new system where the observation of which slit the electron went through is made only after the electron has already landed on the screen and then we store that observation as data or observe it on our own, the interference pattern still does not appear and we see the electrons land on the screen to produce an image of the slits instead. How!? If the our act of observation occurred after the electron had already landed on the screen then how did the electron know that it would be observed in the future?

Now in that same system, instead of storing the data or observing it on our own, if we destroy the data before observing it but after the electron has already landed, then the electrons form the interference pattern on the screen. This makes it seem as if the electron knew that we would destroy the data in the future and hence decided to make an interference pattern.

So what the heck is happening here? Answers are in the video:-

 

Peter

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Good topic. I hope you keep on posting such things even though I can hardly understand a damn thing about this.
 

Rambo101

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Illusion of Time.


People who can't understand , i will try to explain it simple as possible.

This is what we call Einstein 4D static block universe ( eternalism )
CMB_Timeline150-1200x819.jpg


and it arise from relativity of simultaneity principal which is a scientifically proven fact.

• 4D here is 3 dimension + 1 dimension of time.

•What is relativity of simultaneity principal ?

Well it simply means that two spatially separated events occur at the same time are not absolute, but depends on the observer's reference frame.



There is no single now which everyone can agree upon , since time is affected by motion and gravity. In above video Einstein try to explain this to his Friend.

This has huge implications for our perception of not just time but reality as well as it scientifically end the debate for philosophical only now , what we called present as well as any free will.

Past, Present, Future are all equally real.

Past is not gone , future is not no existing , they all exist in Einstein 4D block universe.

past, present and future is nothing more than an illusion.

I will post a quora post by a theoretical physicist who explain it beautifully and easily.

In order to understand what exactly is illusory about past, present and future moments and what knowledge drove those words, you have to gain a little understanding of the concept of relativity.

When we’re inside a fast plane, we can throw a ball straight up and catch it, without the ball suddenly rushing to the back of the plane.

Everything inside that plane will behave exactly like it is not moving very fast at all.

The following ball does not have an absolute speed, as someone outside that train will observe it to be much faster than people on that train:



The Earth on which this train is riding, is rotating around its axis, which is moving around the Sun, which is moving with the Local Group, etc..

This inertia, which is incorporated in Newton’s first law of motion, reveals a very important invariance in relativity: all laws of physics behave exactly the same, no matter our relative constant speed.

But it is another invariance that triggered Einstein to write down those words.

We’d expect, just like that ball on the train, that every speed must be relative, but the speed of light is always measured at the same, constant speed.

This appears impossible. If we’d observe someone in motion at 25% light speed, heading towards some approaching photons at 100% light speed, we’d intuit this observer should measure that light at 125% light speed.



But the thing is, that the massive particles that make up our own bodies and measuring tools, are themselves always moving at the speed of light, but are constantly bumping into particles of the Higgs field, which makes them have a net speed that’s always lower than this speed of light.

Like for instance the top quark:



The net speed of these perpetual light speed interactions between fields that we conveniently understand as these single massive particles through time, might appear slowed down (or even motionless) in respect to us, but they’re still constantly zig-zagging at light speed. They fundamentally can’t not.

This behaviour of our own particles is very much analogous to Einstein’s theoretical light clock. This is a clock that has a certain distance between two mirrors, and it simply counts the received light pulses on top:




When we see a clock that's not moving in respect to us (left image), we’ll see a faster ticking clock, than when it moves in respect to us (right image), because for us these light pulses need to travel a longer distance at its constant speed.

But for the person that's moving along, together with this clock, it's not observed ticking any slower at all, since the rate of change within that person's brains, and all other matter at this velocity, is going exactly in sync with the light clock next to him. Massive particles are like little light clocks themselves.

The second has been defined as exactly the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom at a temperature of 0 K.
The meter is defined as the length of the path traveled by light in a vacuum in 1/299,792,458 of this second.
So, if the duration of a second for a traveler is observed to slow down by a static observer, this traveler will also be observed to measure our distances differently.

So, even though someone in relative constant motion to us notices all laws of physics to still work exactly the same as before he had accelerated to that constant speed, he is observed to be in some different state where he observes the space and time around him differently.

But this state is completely relative. Someone in relative constant motion to us, will observe us in that exact same state as we are observing him.

And this is where things get weird, how can both observers observe the other as time dilated, right?

For that you have to understand that it doesn’t matter how we position that Einstein light clock, when we’re observed to be in constant motion for someone else, it will always be observed to run in sync:



If clocks were behaving differently on their sides, we would be able to tell if we were in absolute constant motion in respect to some aether and all laws of physics wouldn’t be invariant to inertial motion at all. This means clocks on its sides must reveal the exact same time dilation as do clocks perpendicular to the direction of motion, as used earlier in the time dilation thought experiment.

Also these two clocks will therefore be observed to run in sync:


But what’s interesting about this setup, is that we can conclude simultaneous moments of the left clock and the right clock along one dimension of space, when we’re comoving together with those clocks (although we might not really consider ourselves moving at all, of course).

Let’s place time on the y-axis and this single dimension of space on the x-axis so that one second upward has the same distance on the diagram as a light-second sideways, making light move along 45° angles in this (Minkowski) diagram:



Every tick of those clocks creates a “simultaneity line” throughout space. Which of course represents a complete 3D moment for the comoving observer. A snapshot of simultaneous space.

But when we observe those clocks to be in relative motion, the constant speed of light causes the following artefact:



For us, the clock in the rear will always tick earlier than the clock in the front (increase of time is presented downward in this particular diagram), even though these clocks remain equally time dilated as an upright clock would. This is because those clocks have moved a bit, while light was moving at its constant speed. Here’s an example of someone that’s observed moving at a constant speed of 60% light speed:



It is observed to be 20% time dilated as four ticks of the traveler’s clock has passed after five of ours. But we can also see how the traveler measures us, with his own simultaneity lines (moments in his 3D space):



You see how not only the “static” observer measures the other 20% time dilated, so does the “traveler” because of his different opinions about simultaneity.

They also measure each other 20% length contracted with their own view of simultaneity:



The thing is that there’s no preferred, absolute frame of reference and therefore also no absolute, preferred simultaneity. No observer is “right” or “wrong” with their own relative view on simultaneity.

And this is what Einstein meant with the illusion of past, present and future: if time itself would flow at a certain speed (in respect to what, exactly?), where the past is immediately gone and the future is still non-existent, then what is this “real universal 3D moment” that defines these “gone past” and “non-existent future” parts of spacetime, as everyone has their own relative view on what is considered to be the “real moment”?

Just like we intuit the separate three dimensions of space to be this single thing called “space”, we shouldn’t exclude time from that continuum. It is therefore “spacetime”, not “space” and “time”.

Just like we use the Pythagorean theorem dx2+dy2+dz2−−−−−−−−−−−−−√dx2+dy2+dz2 to calculate the distance between two points of simultaneous space to reveal the apparent invariant distance between them, no matter our own relative position to (or how we place the coordinate axes around) these two points:


…so should time be involved in this as well dx2+dy2+dz2−dt2−−−−−−−−−−−−−−−−−√dx2+dy2+dz2−dt2, to get to the real invariant interval of any distance between two events in spacetime. This calculates the invariant distance, regardless of our own relative speed to these two events. In this calculation we should use compatible units for x, y, z and t, like for instance light-seconds and seconds, as these take up the same distances in 4D spacetime. These are called Natural units - Wikipedia.
For invariant time intervals between two events in spacetime, regardless of our own relative motion, we use dt2−dx2−dy2−dz2−−−−−−−−−−−−−−−−−√dt2−dx2−dy2−dz2, again using compatible units.

Here we can see how space and time is observed differently after we’ve changed our relative speed (by acceleration):



Time is on the y-axis, one dimension of space on the x-axis, light moves at 45° angles. All those dots are events, like blips of light by lots of LED’s. The subjective view of the observer in the middle is being revealed of the spacetime around him. Simultaneous events are horizontal and everything that he can literally see are the events that cross the lower ‘ʌ’ of the large ‘X’ of invariant light speed.

You can sometimes see events shift from being located in the past towards being located in the future, when the observer accelerates away from these events, but this does not happen after these events had already passed the ‘ʌ’, placing these already observed events forever inside his own personal, relative past.

But if this continuum of 4D spacetime holds no fundamental flow of time from one moment to the next, as everything of it is all already there, unchanging, then how do we experience this flow subjectively?

Understand that we can never experience two moments at a time.


The current moment is physically completely isolated from the previous moment: all we ever experience is one particular slice in time, where nothing changes. Nothing can change inside a moment, because changes occur over time, never inside an infinitely small moment and we can never have many moments.

But it doesn’t feel like that at all, right? We clearly observe change inside a moment.

All of that is memory. And there are all kinds of memory systems inside our brains.

Imagine you could change into me, from one moment to the next. And I mean me, atom-to-atom. Would you notice the sudden swap?

No, you wouldn’t, because all of those memories that are stored inside me inside this physical moment, will be adopted too.

It will feel as though you were me all along.

Say that you became me, atom-to-atom, at the very instant I put down my cup of tea, right at that moment it hit the table. At this particular instant (that, in this case, doesn’t have an actual, physical neighboring past moment “as me” at all) you are experiencing one infinitely small, isolated moment, that included a little visual memory of me also putting down the cup.

It includes this memory as the experience of actual motion towards putting it down!

That part of experienced motion is memory that doesn’t feel like memory at all. It’s a type of hallucination that feels like it’s actual, clear reality happening right in front of you. But a hallucination based on something that actually exists inside the inaccessible previous moment (that we can only assume to be there).

Have a look at this spiral, which manipulates that motion-memory part inside of our brains. After staring at the thing, look at the picture below it. Notice the motion happening where no actual change exists at all.



That’s how we are able to experience change inside a non-changing moment. And all of our senses have this type of memory. Visual memory is shorter than auditive.

There are people that have these visual memory parts damaged. These people are only capable of seeing the current picture of the present moment, but the hallucination part of motion doesn’t work at all. They’re known for seeing flowing water as a glacier and aren’t capable of noticing if something is approaching them or not. This condition is called Gross akinetopsia - Wikipedia.

So, we are able to

a) experience motion inside our current picture when there’s actually none there


and b) we are able to observe no motion added to our current picture, even though there’s actually motion happening over time.
Just by either manipulating or damaging the parts of our brains that add this hallucination of motion to our current picture of that particular moment.

This is the illusory aspect of time by Einstein.

This may give a feeling of solipsism. But there is no escaping Einstein block universe.
 
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Cruise missile

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Two important but mindbending experiments that make you think of conspiracies where there are none. Clears a lot of concepts:-
1.) Single particle Double slit experiment: When a single electron is fired through a double slit, it lands at a random spot on the screen on the other side of the double slits. But when this experiment is repeated multiple times (with electrons being fired one by one and the location of their fall on the screen being recorded each time), we see that the electrons that fell on the screen form an interference pattern on it. How the heck? Does that mean that an electron passing through the slit knows exactly where (and interferes with) all past electrons (which passed through the slit in the past) and all future electrons (which will pass through the slit in the future) that landed/will land and therefore does it now know where it needs to land such that the end result of it all is a set interference pattern? If not, then how do you explain why sequentially fired electrons still interfere and form a set pattern on the screen on the other side of the slits? Answers are in the video:-




2.) Delayed Choice Quantum Eraser experiment: If in the previous experiment, we try to observe which one of the two slits each of the electrons passes through, the pattern that was forming on the screen suddenly changes. Instead of a pattern, the shape of the two slits forms on the screen (i.e. all electrons fall on the screen so as to form an image of the two slits themselves, instead of an interference pattern). Its as if the electrons suddenly knew that they were being observed! And so the electrons decided to not land on the screen in a pattern, but instead land on the screen to form the shape of the two slits! Its as if either the electrons themselves were conscious, or some conscious being was manipulating each electron to behave in a certain way based on whether we were observing the electrons or not.

Now, if we create a new system where the observation of which slit the electron went through is made only after the electron has already landed on the screen and then we store that observation as data or observe it on our own, the interference pattern still does not appear and we see the electrons land on the screen to produce an image of the slits instead. How!? If the our act of observation occurred after the electron had already landed on the screen then how did the electron know that it would be observed in the future?

Now in that same system, instead of storing the data or observing it on our own, if we destroy the data before observing it but after the electron has already landed, then the electrons form the interference pattern on the screen. This makes it seem as if the electron knew that we would destroy the data in the future and hence decided to make an interference pattern.

So what the heck is happening here? Answers are in the video:-

Well electrons are capable of doing time travel they travel to past where they inform remaining electrons that they are being observed.
 

Rambo101

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Well electrons are capable of doing time travel they travel to past where they inform remaining electrons that they are being observed.
Nope that's not what's happening, it's all about interpretation. Just like there are many Copenhagen interpretation.
 

Okabe Rintarou

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Illusion of Time.

People who can't understand , i will try to explain it simple as possible.

This is what we call Einstein 4D static block universe ( eternalism )
View attachment 78179

and it arise from relativity of simultaneity principal which is a scientifically proven fact.

• 4D here is 3 dimension + 1 dimension of time.

•What is relativity of simultaneity principal ?

Well it simply means that two spatially separated events occur at the same time are not absolute, but depends on the observer's reference frame.




There is no single now which everyone can agree upon , since time is affected by motion and gravity. In above video Einstein try to explain this to his Friend.

This has huge implications for our perception of not just time but reality as well as it scientifically end the debate for philosophical only now , what we called present as well as any free will.

Past, Present, Future are all equally real.

Past is not gone , future is not no existing , they all exist in Einstein 4D block universe.

past, present and future is nothing more than an illusion.

I will post a quora post by a theoretical physicist who explain it beautifully and easily.

In order to understand what exactly is illusory about past, present and future moments and what knowledge drove those words, you have to gain a little understanding of the concept of relativity.

When we’re inside a fast plane, we can throw a ball straight up and catch it, without the ball suddenly rushing to the back of the plane.

Everything inside that plane will behave exactly like it is not moving very fast at all.

The following ball does not have an absolute speed, as someone outside that train will observe it to be much faster than people on that train:



The Earth on which this train is riding, is rotating around its axis, which is moving around the Sun, which is moving with the Local Group, etc..

This inertia, which is incorporated in Newton’s first law of motion, reveals a very important invariance in relativity: all laws of physics behave exactly the same, no matter our relative constant speed.

But it is another invariance that triggered Einstein to write down those words.

We’d expect, just like that ball on the train, that every speed must be relative, but the speed of light is always measured at the same, constant speed.

This appears impossible. If we’d observe someone in motion at 25% light speed, heading towards some approaching photons at 100% light speed, we’d intuit this observer should measure that light at 125% light speed.



But the thing is, that the massive particles that make up our own bodies and measuring tools, are themselves always moving at the speed of light, but are constantly bumping into particles of the Higgs field, which makes them have a net speed that’s always lower than this speed of light.

Like for instance the top quark:



The net speed of these perpetual light speed interactions between fields that we conveniently understand as these single massive particles through time, might appear slowed down (or even motionless) in respect to us, but they’re still constantly zig-zagging at light speed. They fundamentally can’t not.

This behaviour of our own particles is very much analogous to Einstein’s theoretical light clock. This is a clock that has a certain distance between two mirrors, and it simply counts the received light pulses on top:




When we see a clock that's not moving in respect to us (left image), we’ll see a faster ticking clock, than when it moves in respect to us (right image), because for us these light pulses need to travel a longer distance at its constant speed.

But for the person that's moving along, together with this clock, it's not observed ticking any slower at all, since the rate of change within that person's brains, and all other matter at this velocity, is going exactly in sync with the light clock next to him. Massive particles are like little light clocks themselves.


So, if the duration of a second for a traveler is observed to slow down by a static observer, this traveler will also be observed to measure our distances differently.

So, even though someone in relative constant motion to us notices all laws of physics to still work exactly the same as before he had accelerated to that constant speed, he is observed to be in some different state where he observes the space and time around him differently.

But this state is completely relative. Someone in relative constant motion to us, will observe us in that exact same state as we are observing him.

And this is where things get weird, how can both observers observe the other as time dilated, right?

For that you have to understand that it doesn’t matter how we position that Einstein light clock, when we’re observed to be in constant motion for someone else, it will always be observed to run in sync:



If clocks were behaving differently on their sides, we would be able to tell if we were in absolute constant motion in respect to some aether and all laws of physics wouldn’t be invariant to inertial motion at all. This means clocks on its sides must reveal the exact same time dilation as do clocks perpendicular to the direction of motion, as used earlier in the time dilation thought experiment.

Also these two clocks will therefore be observed to run in sync:


But what’s interesting about this setup, is that we can conclude simultaneous moments of the left clock and the right clock along one dimension of space, when we’re comoving together with those clocks (although we might not really consider ourselves moving at all, of course).

Let’s place time on the y-axis and this single dimension of space on the x-axis so that one second upward has the same distance on the diagram as a light-second sideways, making light move along 45° angles in this (Minkowski) diagram:



Every tick of those clocks creates a “simultaneity line” throughout space. Which of course represents a complete 3D moment for the comoving observer. A snapshot of simultaneous space.

But when we observe those clocks to be in relative motion, the constant speed of light causes the following artefact:



For us, the clock in the rear will always tick earlier than the clock in the front (increase of time is presented downward in this particular diagram), even though these clocks remain equally time dilated as an upright clock would. This is because those clocks have moved a bit, while light was moving at its constant speed. Here’s an example of someone that’s observed moving at a constant speed of 60% light speed:



It is observed to be 20% time dilated as four ticks of the traveler’s clock has passed after five of ours. But we can also see how the traveler measures us, with his own simultaneity lines (moments in his 3D space):



You see how not only the “static” observer measures the other 20% time dilated, so does the “traveler” because of his different opinions about simultaneity.

They also measure each other 20% length contracted with their own view of simultaneity:



The thing is that there’s no preferred, absolute frame of reference and therefore also no absolute, preferred simultaneity. No observer is “right” or “wrong” with their own relative view on simultaneity.

And this is what Einstein meant with the illusion of past, present and future: if time itself would flow at a certain speed (in respect to what, exactly?), where the past is immediately gone and the future is still non-existent, then what is this “real universal 3D moment” that defines these “gone past” and “non-existent future” parts of spacetime, as everyone has their own relative view on what is considered to be the “real moment”?

Just like we intuit the separate three dimensions of space to be this single thing called “space”, we shouldn’t exclude time from that continuum. It is therefore “spacetime”, not “space” and “time”.

Just like we use the Pythagorean theorem dx2+dy2+dz2−−−−−−−−−−−−−√dx2+dy2+dz2 to calculate the distance between two points of simultaneous space to reveal the apparent invariant distance between them, no matter our own relative position to (or how we place the coordinate axes around) these two points:


…so should time be involved in this as well dx2+dy2+dz2−dt2−−−−−−−−−−−−−−−−−√dx2+dy2+dz2−dt2, to get to the real invariant interval of any distance between two events in spacetime. This calculates the invariant distance, regardless of our own relative speed to these two events. In this calculation we should use compatible units for x, y, z and t, like for instance light-seconds and seconds, as these take up the same distances in 4D spacetime. These are called Natural units - Wikipedia.
For invariant time intervals between two events in spacetime, regardless of our own relative motion, we use dt2−dx2−dy2−dz2−−−−−−−−−−−−−−−−−√dt2−dx2−dy2−dz2, again using compatible units.

Here we can see how space and time is observed differently after we’ve changed our relative speed (by acceleration):



Time is on the y-axis, one dimension of space on the x-axis, light moves at 45° angles. All those dots are events, like blips of light by lots of LED’s. The subjective view of the observer in the middle is being revealed of the spacetime around him. Simultaneous events are horizontal and everything that he can literally see are the events that cross the lower ‘ʌ’ of the large ‘X’ of invariant light speed.

You can sometimes see events shift from being located in the past towards being located in the future, when the observer accelerates away from these events, but this does not happen after these events had already passed the ‘ʌ’, placing these already observed events forever inside his own personal, relative past.

But if this continuum of 4D spacetime holds no fundamental flow of time from one moment to the next, as everything of it is all already there, unchanging, then how do we experience this flow subjectively?

Understand that we can never experience two moments at a time.


The current moment is physically completely isolated from the previous moment: all we ever experience is one particular slice in time, where nothing changes. Nothing can change inside a moment, because changes occur over time, never inside an infinitely small moment and we can never have many moments.

But it doesn’t feel like that at all, right? We clearly observe change inside a moment.

All of that is memory. And there are all kinds of memory systems inside our brains.

Imagine you could change into me, from one moment to the next. And I mean me, atom-to-atom. Would you notice the sudden swap?

No, you wouldn’t, because all of those memories that are stored inside me inside this physical moment, will be adopted too.

It will feel as though you were me all along.

Say that you became me, atom-to-atom, at the very instant I put down my cup of tea, right at that moment it hit the table. At this particular instant (that, in this case, doesn’t have an actual, physical neighboring past moment “as me” at all) you are experiencing one infinitely small, isolated moment, that included a little visual memory of me also putting down the cup.

It includes this memory as the experience of actual motion towards putting it down!

That part of experienced motion is memory that doesn’t feel like memory at all. It’s a type of hallucination that feels like it’s actual, clear reality happening right in front of you. But a hallucination based on something that actually exists inside the inaccessible previous moment (that we can only assume to be there).

Have a look at this spiral, which manipulates that motion-memory part inside of our brains. After staring at the thing, look at the picture below it. Notice the motion happening where no actual change exists at all.


That’s how we are able to experience change inside a non-changing moment. And all of our senses have this type of memory. Visual memory is shorter than auditive.

There are people that have these visual memory parts damaged. These people are only capable of seeing the current picture of the present moment, but the hallucination part of motion doesn’t work at all. They’re known for seeing flowing water as a glacier and aren’t capable of noticing if something is approaching them or not. This condition is called Gross akinetopsia - Wikipedia.

So, we are able to

a) experience motion inside our current picture when there’s actually none there


and b) we are able to observe no motion added to our current picture, even though there’s actually motion happening over time.
Just by either manipulating or damaging the parts of our brains that add this hallucination of motion to our current picture of that particular moment.

This is the illusory aspect of time by Einstein.

This may give a feeling of solipsism. But there is no escaping Einstein block universe.
Nice post. Appreciated. Illusion of time is a very interesting topic. There is a lot to parse in this post, so I'll leave aside the the part about human perception of time and the part about it ending "free will", for now. We can discuss them once we've figured out my counter-points in this comment. I agree with the simultaneity principle.

But its important we understand that simultaneity principle does not mean causality (cause and effect) itself is violated. To explain this, consider the following scenario:-
There is an alien species extremely far away from us and they are traveling roughly in our direction on their Kugelblitz drive powered spaceship. It could be that their "time slice" is tilted to the extent that according to their definition of the present, our Sun (Sol), has already become a Red Giant. But that alien ship is still in our "time slice".

But the important thing here is that we and the aliens don't know. The aliens don't know yet that Sol has become a Reg Giant in our solar system because that event is still outside of their past light cone. Similarly, we don't know that there is such a ship coming towards us because the ship is outside our past light cone. There is no way for the aliens to pass on the information about how our Red Giant Sol looks in the future to us before our Sol actually turns into a Red Giant according to our own illusion of time.

So we live in a world that is locally more or less approximated by presentism. The massive differences in perception of time that arise, do so when the two observers are very far apart in space. Small differences can be felt, as they are in atomic clocks of IRNSS and GPS satellites.

But the problem with your assertion begins with the line:-
"But if this continuum of 4D spacetime holds no fundamental flow of time from one moment to the next, as everything of it is all already there, unchanging, then how do we experience this flow subjectively"
This seems wrong to me, for a few reasons:-
1.) Entropy: Despite quantum fluctuations, on a macroscopic scale, entropy only increases in the universe. Going down to length scales that are governed by quantum mechanics, it does seem as if entropy is reversible. But macroscopically, we have observed that that is not the case. Macroscopically, Second Law of Thermodynamics always holds.

2.) Time symmetry has been broken: Quarks held together by strong force in the nucleus of an atom take more time to switch between states A and B than they take to switch between B and A.

3.) Speed in time: The third video in my second comment on this thread explains this concept. We all move at the speed of light, as long as we are travelling in Minkowski space, that is.

So without trying to delve into how humans can "feel the flow of time", we have two physically verifiable laws that break the time symmetry, showing that time indeed does flow. Yes time is not absolute, but that doesn't mean that its completely an illusion and that the future is already pre-determined. Well, lets leave the "pre-determined" part for now, but its not as if time doesn't flow. It does flow.

My points are explained by these videos:-
1.) Entropy

2.) Time symmetry broken

3.) Speed in time

 

Okabe Rintarou

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Illusion of Time.


People who can't understand , i will try to explain it simple as possible.

This is what we call Einstein 4D static block universe ( eternalism )
View attachment 78179

and it arise from relativity of simultaneity principal which is a scientifically proven fact.

• 4D here is 3 dimension + 1 dimension of time.

•What is relativity of simultaneity principal ?

Well it simply means that two spatially separated events occur at the same time are not absolute, but depends on the observer's reference frame.



There is no single now which everyone can agree upon , since time is affected by motion and gravity. In above video Einstein try to explain this to his Friend.

This has huge implications for our perception of not just time but reality as well as it scientifically end the debate for philosophical only now , what we called present as well as any free will.

Past, Present, Future are all equally real.

Past is not gone , future is not no existing , they all exist in Einstein 4D block universe.

past, present and future is nothing more than an illusion.

I will post a quora post by a theoretical physicist who explain it beautifully and easily.

In order to understand what exactly is illusory about past, present and future moments and what knowledge drove those words, you have to gain a little understanding of the concept of relativity.

When we’re inside a fast plane, we can throw a ball straight up and catch it, without the ball suddenly rushing to the back of the plane.

Everything inside that plane will behave exactly like it is not moving very fast at all.

The following ball does not have an absolute speed, as someone outside that train will observe it to be much faster than people on that train:



The Earth on which this train is riding, is rotating around its axis, which is moving around the Sun, which is moving with the Local Group, etc..

This inertia, which is incorporated in Newton’s first law of motion, reveals a very important invariance in relativity: all laws of physics behave exactly the same, no matter our relative constant speed.

But it is another invariance that triggered Einstein to write down those words.

We’d expect, just like that ball on the train, that every speed must be relative, but the speed of light is always measured at the same, constant speed.

This appears impossible. If we’d observe someone in motion at 25% light speed, heading towards some approaching photons at 100% light speed, we’d intuit this observer should measure that light at 125% light speed.



But the thing is, that the massive particles that make up our own bodies and measuring tools, are themselves always moving at the speed of light, but are constantly bumping into particles of the Higgs field, which makes them have a net speed that’s always lower than this speed of light.

Like for instance the top quark:



The net speed of these perpetual light speed interactions between fields that we conveniently understand as these single massive particles through time, might appear slowed down (or even motionless) in respect to us, but they’re still constantly zig-zagging at light speed. They fundamentally can’t not.

This behaviour of our own particles is very much analogous to Einstein’s theoretical light clock. This is a clock that has a certain distance between two mirrors, and it simply counts the received light pulses on top:




When we see a clock that's not moving in respect to us (left image), we’ll see a faster ticking clock, than when it moves in respect to us (right image), because for us these light pulses need to travel a longer distance at its constant speed.

But for the person that's moving along, together with this clock, it's not observed ticking any slower at all, since the rate of change within that person's brains, and all other matter at this velocity, is going exactly in sync with the light clock next to him. Massive particles are like little light clocks themselves.


So, if the duration of a second for a traveler is observed to slow down by a static observer, this traveler will also be observed to measure our distances differently.

So, even though someone in relative constant motion to us notices all laws of physics to still work exactly the same as before he had accelerated to that constant speed, he is observed to be in some different state where he observes the space and time around him differently.

But this state is completely relative. Someone in relative constant motion to us, will observe us in that exact same state as we are observing him.

And this is where things get weird, how can both observers observe the other as time dilated, right?

For that you have to understand that it doesn’t matter how we position that Einstein light clock, when we’re observed to be in constant motion for someone else, it will always be observed to run in sync:



If clocks were behaving differently on their sides, we would be able to tell if we were in absolute constant motion in respect to some aether and all laws of physics wouldn’t be invariant to inertial motion at all. This means clocks on its sides must reveal the exact same time dilation as do clocks perpendicular to the direction of motion, as used earlier in the time dilation thought experiment.

Also these two clocks will therefore be observed to run in sync:


But what’s interesting about this setup, is that we can conclude simultaneous moments of the left clock and the right clock along one dimension of space, when we’re comoving together with those clocks (although we might not really consider ourselves moving at all, of course).

Let’s place time on the y-axis and this single dimension of space on the x-axis so that one second upward has the same distance on the diagram as a light-second sideways, making light move along 45° angles in this (Minkowski) diagram:



Every tick of those clocks creates a “simultaneity line” throughout space. Which of course represents a complete 3D moment for the comoving observer. A snapshot of simultaneous space.

But when we observe those clocks to be in relative motion, the constant speed of light causes the following artefact:



For us, the clock in the rear will always tick earlier than the clock in the front (increase of time is presented downward in this particular diagram), even though these clocks remain equally time dilated as an upright clock would. This is because those clocks have moved a bit, while light was moving at its constant speed. Here’s an example of someone that’s observed moving at a constant speed of 60% light speed:



It is observed to be 20% time dilated as four ticks of the traveler’s clock has passed after five of ours. But we can also see how the traveler measures us, with his own simultaneity lines (moments in his 3D space):



You see how not only the “static” observer measures the other 20% time dilated, so does the “traveler” because of his different opinions about simultaneity.

They also measure each other 20% length contracted with their own view of simultaneity:



The thing is that there’s no preferred, absolute frame of reference and therefore also no absolute, preferred simultaneity. No observer is “right” or “wrong” with their own relative view on simultaneity.

And this is what Einstein meant with the illusion of past, present and future: if time itself would flow at a certain speed (in respect to what, exactly?), where the past is immediately gone and the future is still non-existent, then what is this “real universal 3D moment” that defines these “gone past” and “non-existent future” parts of spacetime, as everyone has their own relative view on what is considered to be the “real moment”?

Just like we intuit the separate three dimensions of space to be this single thing called “space”, we shouldn’t exclude time from that continuum. It is therefore “spacetime”, not “space” and “time”.

Just like we use the Pythagorean theorem dx2+dy2+dz2−−−−−−−−−−−−−√dx2+dy2+dz2 to calculate the distance between two points of simultaneous space to reveal the apparent invariant distance between them, no matter our own relative position to (or how we place the coordinate axes around) these two points:


…so should time be involved in this as well dx2+dy2+dz2−dt2−−−−−−−−−−−−−−−−−√dx2+dy2+dz2−dt2, to get to the real invariant interval of any distance between two events in spacetime. This calculates the invariant distance, regardless of our own relative speed to these two events. In this calculation we should use compatible units for x, y, z and t, like for instance light-seconds and seconds, as these take up the same distances in 4D spacetime. These are called Natural units - Wikipedia.
For invariant time intervals between two events in spacetime, regardless of our own relative motion, we use dt2−dx2−dy2−dz2−−−−−−−−−−−−−−−−−√dt2−dx2−dy2−dz2, again using compatible units.

Here we can see how space and time is observed differently after we’ve changed our relative speed (by acceleration):



Time is on the y-axis, one dimension of space on the x-axis, light moves at 45° angles. All those dots are events, like blips of light by lots of LED’s. The subjective view of the observer in the middle is being revealed of the spacetime around him. Simultaneous events are horizontal and everything that he can literally see are the events that cross the lower ‘ʌ’ of the large ‘X’ of invariant light speed.

You can sometimes see events shift from being located in the past towards being located in the future, when the observer accelerates away from these events, but this does not happen after these events had already passed the ‘ʌ’, placing these already observed events forever inside his own personal, relative past.

But if this continuum of 4D spacetime holds no fundamental flow of time from one moment to the next, as everything of it is all already there, unchanging, then how do we experience this flow subjectively?

Understand that we can never experience two moments at a time.


The current moment is physically completely isolated from the previous moment: all we ever experience is one particular slice in time, where nothing changes. Nothing can change inside a moment, because changes occur over time, never inside an infinitely small moment and we can never have many moments.

But it doesn’t feel like that at all, right? We clearly observe change inside a moment.

All of that is memory. And there are all kinds of memory systems inside our brains.

Imagine you could change into me, from one moment to the next. And I mean me, atom-to-atom. Would you notice the sudden swap?

No, you wouldn’t, because all of those memories that are stored inside me inside this physical moment, will be adopted too.

It will feel as though you were me all along.

Say that you became me, atom-to-atom, at the very instant I put down my cup of tea, right at that moment it hit the table. At this particular instant (that, in this case, doesn’t have an actual, physical neighboring past moment “as me” at all) you are experiencing one infinitely small, isolated moment, that included a little visual memory of me also putting down the cup.

It includes this memory as the experience of actual motion towards putting it down!

That part of experienced motion is memory that doesn’t feel like memory at all. It’s a type of hallucination that feels like it’s actual, clear reality happening right in front of you. But a hallucination based on something that actually exists inside the inaccessible previous moment (that we can only assume to be there).

Have a look at this spiral, which manipulates that motion-memory part inside of our brains. After staring at the thing, look at the picture below it. Notice the motion happening where no actual change exists at all.



That’s how we are able to experience change inside a non-changing moment. And all of our senses have this type of memory. Visual memory is shorter than auditive.

There are people that have these visual memory parts damaged. These people are only capable of seeing the current picture of the present moment, but the hallucination part of motion doesn’t work at all. They’re known for seeing flowing water as a glacier and aren’t capable of noticing if something is approaching them or not. This condition is called Gross akinetopsia - Wikipedia.

So, we are able to

a) experience motion inside our current picture when there’s actually none there


and b) we are able to observe no motion added to our current picture, even though there’s actually motion happening over time.
Just by either manipulating or damaging the parts of our brains that add this hallucination of motion to our current picture of that particular moment.

This is the illusory aspect of time by Einstein.

This may give a feeling of solipsism. But there is no escaping Einstein block universe.
There are a few more concepts we need to understand before we begin to claim that future, past and present are irrelevant. Some of these is the concept of worldlines, proper time and spacetime interval. Will cover these topics later on.

Well electrons are capable of doing time travel they travel to past where they inform remaining electrons that they are being observed.
Not exactly. I wrote it like that purposefully because it appears that that is the case, but it isn't. Watch the video, its an illusion that the electrons can "travel to the past". It has to do with the concept of De-Broglie waves.
BTW, why did you get banned!?
 

Rambo101

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There are a few more concepts we need to understand before we begin to claim that future, past and present are irrelevant. Some of these is the concept of worldlines, proper time and spacetime interval. Will cover these topics later on.
I never said that future, past and present are irrelevant. I said they all exist and are equally real and gone past and non existing future is mere an illusion.
.
There is an alien species extremely far away from us and they are traveling roughly in our direction on their Kugelblitz drive powered spaceship. It could be that their "time slice" is tilted to the extent that according to their definition of the present, our Sun (Sol), has already become a Red Giant. But that alien ship is still in our "time slice".

But the important thing here is that we and the aliens don't know. The aliens don't know yet that Sol has become a Reg Giant in our solar system because that event is still outside of their past light cone. Similarly, we don't know that there is such a ship coming towards us because the ship is outside our past light cone. There is no way for the aliens to pass on the information about how our Red Giant Sol looks in the future to us before our Sol actually turns into a Red Giant according to our own illusion of time.

So we live in a world that is locally more or less approximated by presentism. The massive differences in perception of time that arise, do so when the two observers are very far apart in space. Small differences can be felt, as they are in atomic clocks of IRNSS and GPS satellites.
Yes it's true but the difference is there and it exist no matter how small. Which can mean only one thing , that all of time is out there like all of space. Einstein realise this and it's implications and boom! time emerge as a true 4th dimension for him on par with other three.
our perception of time is bound by our physical limit as a 3D being in a 4D spacetime. I will explain it below along with answering your other point.
.
This seems wrong to me, for a few reasons:-
1.) Entropy: Despite quantum fluctuations, on a macroscopic scale, entropy only increases in the universe. Going down to length scales that are governed by quantum mechanics, it does seem as if entropy is reversible. But macroscopically, we have observed that that is not the case. Macroscopically, Second Law of Thermodynamics always holds.
Things moving from order to disorder ( entropy ) should not be confused with time or property of time dimension itself. Time doesn't flow at all in reality , it's all in your head nothing else.

we perceive flow of time because our brain contain Memories inside the present moment and when you actually observe a motion or change over time , you are actually observing a quantum mechanical influence of an unreachable but nearby location in time.

so why don't we remember future but remember past ? and feel this arrow of time to the future ?

well for simple reason your brain memories start from low entropy state and future has high entropy, which make it easy for us to understand details of nearby moments in the past, than moments of the near future. all you observe is short static recording, frame by frame like a DVD is run frame by frame.

as for entropy There is nothing in physics that says that the reverse situation is impossible, it just say it's highly unlikely not impossible.

so why we have this entropy and illusion of flow of time at all ? Well for that you have to go in past and what we see there ? Order.

But it doesn’t matter on which side of the temporal dimension you place the perfectly ordered event we call Big Bang , as soon as you let the laws of physics have a go at it, things will become more disordered from order.

Psychological time is always in the direction away from order. But this is not a fundamental property of the time dimension itself . It’s somewhat like space having the appearance of having a fundamental direction for us as well, here on Earth:



Antiparticles that can be interpreted as the regular particle going back in time.

1200px-Mutual_Annihilation_of_a_Positron_Electron_pair.svg.png


What you see here is an interaction between a particle (electron) and its antiparticle (positron) that annihilate and leave two photons. Time is up, 1 dimension of space is on the x-axis. An electron comes in from the left, and meets its antiparticle from the right, the positron. You can slide a ruler moving upward to see what’s going on.

Now, there is a symmetry, implied by Quantum Field Theory, that is never violated by any known process. It’s called the CPT (charge-parity-time) symmetry, and it says that if you take the Universe and everything in it and flip the electrical charge (C), invert everything as though through a mirror (P), and reverse the direction of time (T), then the base laws of physics all continue to work the same.

What we call anti-particles, are charge and parity (CP) reversed particles, that therefore behave exactly like time reversed, normal particles.

This is why that arrow was placed there in the Feynman diagram on the positron going backwards in time.

The other way is equally viable: two photons meeting up creating an electron and a positron, which can equally be seen as a positron coming in from the future, changing its direction of time, now looking like an electron to us, but having no existence at all in our past.

What’s also interesting, is that you can also always flip time and space and still get a viable Feynman diagram. This is called crossing symmetry. In this case, it would look like an electron first being hit by a photon from the right and then emitting a photon back into space towards the right, changing the electron’s motion towards the left, twice.
 
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Okabe Rintarou

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Was going ask if it is possible to go faster to the speed of light ...

Since "speed of light" can be measured theoretically. on earth itself can we transport faster to speed of light.
Its simply not possible to go faster than speed of light. But that is not light's fault. Speed of light is not about light, but about "Causality". Causality is the fundamental reality of our spacetime, at least as far as Special Relativity goes. It means "Cause and Effect". Every single event in the universe has a cause. The effect of that cause is the event. The speed of light is the speed limit at which information about an event can travel. Any Cause can't cause an Effect faster than the speed of light. If a star goes Supernova 50 light years away, no amount of technology or anything else will allow us to receive that information less than 50 years after the star goes supernova. Hence, the supernova can't cause anything 50 light-years away until at least 50 years after it goes off.

A closed loop of cause and effect can also never form (unless inside the event horizon of a blackhole, but that is a different matter entirely). Paradoxes commonly associated with time travel (such as if I go back in time and kill myself, will I still be alive) can never occur because of Causality and the Speed of Light.

This video might do a better job of explaining this concept:-



I never said that future, past and present are irrelevant. I said they all exist and are equally real and gone past and non existing future is mere an illusion.

Yes it's true but the difference is there and it exist no matter how small. Which can mean only one thing , that all of time is out there like all of space. Einstein realise this and it's implications and boom! time emerge as a true 4th dimension for him on par with other three.
our perception of time is bound by our physical limit as a 3D being in a 4D spacetime. I will explain it below along with answering your other point.

Things moving from order to disorder ( entropy ) should not be confused with time or property of time dimension itself. Time doesn't flow at all in reality , it's all in your head nothing else.

we perceive flow of time because our brain contain Memories inside the present moment and when you actually observe a motion or change over time , you are actually observing a quantum mechanical influence of an unreachable but nearby location in time.

so why don't we remember future but remember past ? and feel this arrow of time to the future ?

well for simple reason your brain memories start from low entropy state and future has high entropy, which make it easy for us to understand details of nearby moments in the past, than moments of the near future. all you observe is short static recording, frame by frame like a DVD is run frame by frame.

as for entropy There is nothing in physics that says that the reverse situation is impossible, it just say it's highly unlikely not impossible.

so why we have this entropy and illusion of flow of time at all ? Well for that you have to go in past and what we see there ? Order.

But it doesn’t matter on which side of the temporal dimension you place the perfectly ordered event we call Big Bang , as soon as you let the laws of physics have a go at it, things will become more disordered from order.

Psychological time is always in the direction away from order. But this is not a fundamental property of the time dimension itself . It’s somewhat like space having the appearance of having a fundamental direction for us as well, here on Earth:



Antiparticles that can be interpreted as the regular particle going back in time.

View attachment 78316

What you see here is an interaction between a particle (electron) and its antiparticle (positron) that annihilate and leave two photons. Time is up, 1 dimension of space is on the x-axis. An electron comes in from the left, and meets its antiparticle from the right, the positron. You can slide a ruler moving upward to see what’s going on.

Now, there is a symmetry, implied by Quantum Field Theory, that is never violated by any known process. It’s called the CPT (charge-parity-time) symmetry, and it says that if you take the Universe and everything in it and flip the electrical charge (C), invert everything as though through a mirror (P), and reverse the direction of time (T), then the base laws of physics all continue to work the same.

What we call anti-particles, are charge and parity (CP) reversed particles, that therefore behave exactly like time reversed, normal particles.

This is why that arrow was placed there in the Feynman diagram on the positron going backwards in time.

The other way is equally viable: two photons meeting up creating an electron and a positron, which can equally be seen as a positron coming in from the future, changing its direction of time, now looking like an electron to us, but having no existence at all in our past.

What’s also interesting, is that you can also always flip time and space and still get a viable Feynman diagram. This is called crossing symmetry. In this case, it would look like an electron first being hit by a photon from the right and then emitting a photon back into space towards the right, changing the electron’s motion towards the left, twice.
From what I understand, your interpretation of time is that the past, present and future all exist and so time is traversable similar to how the three dimensions all exist and are traversable. But I think you are disregarding the very geometry of spacetime. Keeping things a bit simple, according to Special Relativity, spacetime is a Minkowski Space, which is fundamentally different from 4D Euclidean space. Minkowski space is a non-Euclidean space. This tells us that temporal dimensions are fundamentally different from spatial dimensions. This is why the measure analogous to "distance" of 3D Euclidian Space in Minkowski Space is "spacetime interval". This spacetime interval is independent of frames of reference and is the very reason why 3D space and time were even considered to be "spacetime".

This crucial difference between the three spatial dimensions and the one temporal dimension of Einstein's 4D block universe ensures that time travel is simply impossible. Time can not be traversed the same way as space can be. I know it sounds ironic coming from me, seeing as I am Okabe Rintarou (the protagonist of a time-travel anime), but until we have a theory of Quantum Gravity, we really can't be sure.

Please tell me if you concur with this or if I am making a mistake somewhere. After that, I'll explain why entropy does indeed imply a natural direction of flow for time and why anti-matter like positron is not exactly "particles traveling back in time".
 

Rambo101

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Its simply not possible to go faster than speed of light. But that is not light's fault. Speed of light is not about light, but about "Causality". Causality is the fundamental reality of our spacetime, at least as far as Special Relativity goes. It means "Cause and Effect". Every single event in the universe has a cause. The effect of that cause is the event. The speed of light is the speed limit at which information about an event can travel. Any Cause can't cause an Effect faster than the speed of light. If a star goes Supernova 50 light years away, no amount of technology or anything else will allow us to receive that information less than 50 years after the star goes supernova. Hence, the supernova can't cause anything 50 light-years away until at least 50 years after it goes off.

A closed loop of cause and effect can also never form (unless inside the event horizon of a blackhole, but that is a different matter entirely). Paradoxes commonly associated with time travel (such as if I go back in time and kill myself, will I still be alive) can never occur because of Causality and the Speed of Light.

This video might do a better job of explaining this concept:-




From what I understand, your interpretation of time is that the past, present and future all exist and so time is traversable similar to how the three dimensions all exist and are traversable. But I think you are disregarding the very geometry of spacetime. Keeping things a bit simple, according to Special Relativity, spacetime is a Minkowski Space, which is fundamentally different from 4D Euclidean space. Minkowski space is a non-Euclidean space. This tells us that temporal dimensions are fundamentally different from spatial dimensions. This is why the measure analogous to "distance" of 3D Euclidian Space in Minkowski Space is "spacetime interval". This spacetime interval is independent of frames of reference and is the very reason why 3D space and time were even considered to be "spacetime".

This crucial difference between the three spatial dimensions and the one temporal dimension of Einstein's 4D block universe ensures that time travel is simply impossible. Time can not be traversed the same way as space can be. I know it sounds ironic coming from me, seeing as I am Okabe Rintarou (the protagonist of a time-travel anime), but until we have a theory of Quantum Gravity, we really can't be sure.

Please tell me if you concur with this or if I am making a mistake somewhere. After that, I'll explain why entropy does indeed imply a natural direction of flow for time and why anti-matter like positron is not exactly "particles traveling back in time".
.Speed in time: The third video in my second comment on this thread explains this concept. We all move at the speed of light, as long as we are travelling in Minkowski space, that is.
Minkowski spacetime doesn’t actually say we are moving through time at any speed. It merely reveals intervals between spacetime events.

A particle’s own distances in time does not mean it has a speed, there. The ‘c’ in the spacetime interval s=x2+y2+z2−(ct)2−−−−−−−−−−−−−−−−√s=x2+y2+z2−(ct)2 is just a number used as an exchange rate between our units for time and distances. Like 5280 feet per mile. So c is not a speed, but a constant (that's what that c stands for).

Also, the c is not there when we’re using Natural units - Wikipedia.

Spacetime is unified into one, single continuum, so time should not be seen as separate from space.

Minkowski spacetime represents a 4D picture of events. Nothing is moving in a picture. You are an unchanging 4D body in Minkowski spacetime.

four-dimensional-space-five-dimensional-space-eternalism-tesseract-png-favpng-JThjnR85rxQEuDuD...jpg


So, as soon as you imagine 4D objects in Minkowski diagrams to actually represent 3D bodies going through time at a certain speed, much in the way your 3D car could be driving through space, you are confusing yourself.

The flow of time that we all consciously experience in any moment, where things are clearly changing all the time and always from the past towards the future direction are all phenomena that stop as soon as very specific parts of our brains stop functioning.

In other words, the experience of flow is not fundamental to physical time itself, but a result of our complex biology.

This GIF can manipulate the visual memory parts that are responsible for the experience of visual change. It will show you that things can appear to move when there’s really nothing moving “out there”:
:



These brain parts we’ve manipulated here, are also responsible for adding the sense of visual change to the currently observed location(!) of, say, a moving car.

There are people that have these visual memory parts damaged. These people are only capable of seeing the current picture of the present moment, but the hallucination part of motion doesn’t work at all. They’re known for seeing flowing water as a glacier and aren’t capable of noticing if something is approaching them or not. This condition is called Gross akinetopsia - Wikipedia.

Now, if you really were a 3D body moving through time at some speed, very much like that car moving through space with a certain speed, you would be able to observe more than a single moment of it, would you agree? You would watch a whole “time scenery” pass by, much like watching the spatial scenery pass by in the car, right?

We might intuitively believe that we do, but imagine you could change into me, from one moment to the next. And I mean me, atom-to-atom. Would you notice the sudden change as part of this “time scenery”?

No, you wouldn’t, because all of those memories that are stored inside me, inside this physical moment, will be adopted too.

It will feel as though you were me all along. So that sense of me-through-time is biological, not fundamental to physical time itself.
Every moment is really very isolated from the previous and the next, no matter how much they influence each other.

Say that you became me, atom-to-atom, at the very instant I put down my cup of tea, right at that moment it hit the table. At this particular instant (that, in this case, doesn’t have an actual, physical neighboring past moment “as me” at all) you are experiencing one infinitely small, isolated moment, that included a little visual memory of me also putting down the cup.

It includes this memory as the experience of actual motion towards putting it down.

That part of experienced motion is memory that doesn’t feel like memory at all. It’s a type of hallucination that feels like it’s actual, clear reality happening right in front of you. But a hallucination based on something that actually exists inside the inaccessible previous moment (that we can only assume to be there).

So this biological sense of flow cannot be said to go at any speed, because the observed change inside the moment is illusory.

Time should be regarded as a dimension of spacetime, as relativity theory holds - so it does not pass by us in some way, because spacetime doesn’t. Instead, time is part of the uniform larger fabric of the universe, not something moving around inside it. - Does time pass? - MIT News
I copy pasted it from other site. as it's easy to understand this way.
 

Rambo101

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Its simply not possible to go faster than speed of light. But that is not light's fault. Speed of light is not about light, but about "Causality". Causality is the fundamental reality of our spacetime, at least as far as Special Relativity goes. It means "Cause and Effect". Every single event in the universe has a cause. The effect of that cause is the event. The speed of light is the speed limit at which information about an event can travel. Any Cause can't cause an Effect faster than the speed of light. If a star goes Supernova 50 light years away, no amount of technology or anything else will allow us to receive that information less than 50 years after the star goes supernova. Hence, the supernova can't cause anything 50 light-years away until at least 50 years after it goes off.

A closed loop of cause and effect can also never form (unless inside the event horizon of a blackhole, but that is a different matter entirely). Paradoxes commonly associated with time travel (such as if I go back in time and kill myself, will I still be alive) can never occur because of Causality and the Speed of Light.

This video might do a better job of explaining this concept:-




. But I think you are disregarding the very geometry of spacetime. Keeping things a bit simple, according to Special Relativity, spacetime is a Minkowski Space, which is fundamentally different from 4D Euclidean space. Minkowski space is a non-Euclidean space. This tells us that temporal dimensions are fundamentally different from spatial dimensions. This is why the measure analogous to "distance" of 3D Euclidian Space in Minkowski Space is "spacetime interval". This spacetime interval is independent of frames of reference and is the very reason why 3D space and time were even considered to be "spacetime".

This crucial difference between the three spatial dimensions and the one temporal dimension of Einstein's 4D block universe ensures that time travel is simply impossible. Time can not be traversed the same way as space can be. I know it sounds ironic coming from me, seeing as I am Okabe Rintarou (the protagonist of a time-travel anime), but until we have a theory of Quantum Gravity, we really can't be sure.

Please tell me if you concur with this or if I am making a mistake somewhere. After that, I'll explain why entropy does indeed imply a natural direction of flow for time and why anti-matter like positron is not exactly "particles traveling back in time".
. From what I understand, your interpretation of time is that the past, present and future all exist and so time is traversable similar to how the three dimensions all exist and are traversable
no i said that past, present , future all exist and are equally real and passage of time is merely an illusion .I never said time is traversable or not. It's not that what i want but what we get from relativity of simultaneity.

In the Lorentz transformation animation below, with time on the y, space on x, and the large “X” as invariant light speed, you can see how events (moments in space, depicted here as dots) sometimes move from past to future, when the observer travels away from this direction at relativistic speeds.

main-qimg-00f0c244af5fd2fd55ded040b458e400 (2).gif


another depiction.
Relativity_of_Simultaneity_Animation.gif


So, if we assume the past is gone and the future non-existent, with a fundamental “flow of time” (with a “speed of time” relative to what exactly, as “speed” already has the unit of time in it?) then we have to find this “absolute 3D now” that every moving body must agree upon, in order to define which parts of spacetime are either already gone or still non-existent.

And this has been revealed to be absolutely impossible, as simultaneity has shown to be a completely relative convention of ours. Everyone has another opposing “real moment”. My now can be included in your now, while your now is not within in my now, but in my past or future, because of our relative motion towards each other.

This is why this has become such a prominent interpretation among physicists, even if it goes against things we are commonly strongly attached to, such as a very strong early intuition, our sense of free will and, for some, religion.

Prof Brian Greene video on it .

 
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leon66

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European Space Assosiation and NASA are going to make a partnership in the environmental project. The first-ever partnership of its kind is based on observing Earth and environmental issues. This campaign will be based on observing the Earth from space with the help of satellite technology in order to save the environment on Earth. Such kind of stuff will be observed like coral reefs, glaciers, and other things that are in danger now.
 

leon66

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Actually, such kind of sats has already been used by some space agencies from Europe and from other counties in order to observe particular areas like coral reefs and mountainous regions. These regions are the most vulnerable across the globe and have undergone dramatic changes in the last few decades. That is why the observation with the help of satellite technology is vital.
 

Mantospace

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If any body hav seen movie the tmrow war. In that guy travel to 30 years ahead and meet his daughter as army leutenant. Daughter said to her father that i seen u dying and left us. But father said i never live that then hw do i know.

is it possible ?
 

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