How does time work?

How does science work? And what's all this about quantum mechanics?

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uwot
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Re: How does time work?

Post by uwot » Fri Aug 03, 2018 1:08 pm

Cerveny wrote:
Fri Aug 03, 2018 12:38 pm
Einstein has not proved anything. He supposed (right) limited speed (~~c) of universe growth/condensation only. The existence of aether/ physical space he realised too late... He misunderstood “growth/crystalisation” of the universe, he interpreted it as obscure “expansion”:(
Blimey Cerveny, you are digging up some old stuff, and I wouldn't bother asking bobevenson anything. The blog page this thread relates to is long since deleted. Anyone interested in the updated version will have to scroll down to page 39 here: http://willijbouwman.blogspot.co.uk
Anyway, Einstein not only believed that 'spacetime' is a substance with mechanical properties, he gave a lecture titled Ether and the theory of relativity: http://www-history.mcs.st-andrews.ac.uk ... ether.html in which he explicitly said so.
On top of that, Einstein did not originally interpret anything as expansion and famously had to include the 'cosmological constant' to explain why gravity was not causing the universe to shrink. It was only after Einstein shuffled off this mortal coil that Penzias and Wilson discovered the cosmic microwave background radiation that the Big Bang theory really put other hypotheses in the shade.
As for your "growth/crystallisation", it's an interesting idea, but how do you account for the observed galactic redshift?

thedoc
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Re: How does time work?

Post by thedoc » Fri Aug 03, 2018 8:28 pm

uwot wrote:
Fri Aug 03, 2018 1:08 pm
Cerveny wrote:
Fri Aug 03, 2018 12:38 pm
Einstein has not proved anything. He supposed (right) limited speed (~~c) of universe growth/condensation only. The existence of aether/ physical space he realised too late... He misunderstood “growth/crystalisation” of the universe, he interpreted it as obscure “expansion”:(
Blimey Cerveny, you are digging up some old stuff, and I wouldn't bother asking bobevenson anything. The blog page this thread relates to is long since deleted. Anyone interested in the updated version will have to scroll down to page 39 here: http://willijbouwman.blogspot.co.uk
Anyway, Einstein not only believed that 'spacetime' is a substance with mechanical properties, he gave a lecture titled Ether and the theory of relativity: http://www-history.mcs.st-andrews.ac.uk ... ether.html in which he explicitly said so.
On top of that, Einstein did not originally interpret anything as expansion and famously had to include the 'cosmological constant' to explain why gravity was not causing the universe to shrink. It was only after Einstein shuffled off this mortal coil that Penzias and Wilson discovered the cosmic microwave background radiation that the Big Bang theory really put other hypotheses in the shade.
As for your "growth/crystallisation", it's an interesting idea, but how do you account for the observed galactic redshift?
Einstein abandon the "cosmological constant" after Hubble had discovered that the universe was expanding, hence the Hubble's law for the expanding Universe. Yes the CMBR sealed the deal of an Expanding Universe and the Big Bang.

Dubious
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Re: How does time work?

Post by Dubious » Fri Aug 03, 2018 8:56 pm

It makes things older until age makes it disappear entirely. That's my "scientific" conclusion!

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Cerveny
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Re: How does time work?

Post by Cerveny » Fri Aug 03, 2018 9:09 pm

uwot wrote:
Fri Aug 03, 2018 1:08 pm
Cerveny wrote:
Fri Aug 03, 2018 12:38 pm
Einstein has not proved anything. He supposed (right) limited speed (~~c) of universe growth/condensation only. The existence of aether/ physical space he realised too late... He misunderstood “growth/crystalisation” of the universe, he interpreted it as obscure “expansion”:(
Blimey Cerveny, you are digging up some old stuf
f...
As for your "growth/crystallisation", it's an interesting idea, but how do you account for the observed galactic redshift?
Universe crystallizes from the Future. Vacuum (its history) is an ideal crystal. Elementary particles are some structural defects in it (see screw dislocation, eg). The time of Now is some kind of (live) phase border between the History and the Future. The solid History is just setting, built during a rather accidental quantum interactions (“measurements!?”). Before “Big Bang” was only “Future” - the Platonic’s Empire if Ideas...

gaffo
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Re: How does time work?

Post by gaffo » Sat Aug 04, 2018 3:33 am

Noax wrote:
Sun Mar 05, 2017 1:36 pm
Time as a coordinate system.
no, that is space.

time is the 4th dimension.


Noax wrote:
Sun Mar 05, 2017 1:36 pm
Unlike the gravitation field in which a thing finds itself, speed is not a property of a thing,

nope - velocity and gravitiation field have the SAME effect upom matter.

they are the same!

matter increases in mass in both a gravity well and with speed.

same effect.


Noax wrote:
Sun Mar 05, 2017 1:36 pm
so speed cannot make something happen slower.

again, nope, speed/gravity (same thing) slows time for the object in question.

Noax wrote:
Sun Mar 05, 2017 1:36 pm
If you want to teach really basic relativity, a longer comic might be required. Actually nothing ever happens slower.
light travelling in space will give you zero time.

so nope, you are wrong.
Noax wrote:
Sun Mar 05, 2017 1:36 pm
Two events (one of a pair of twins saying goodbye to the other as he boards the rocket, and the event of their subsequent reunion) are separated by different amounts of time depending on the path taken. The path with excessive spatial displacement requires less time displacement to connect the two events. This is unintuitive since it seems to violate euclidean geometry, but so does the gravity thing, so Euclid was already out the window.
gravity wells will give you the result.

you left that out.

gaffo
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Re: How does time work?

Post by gaffo » Sat Aug 04, 2018 3:41 am

Noax wrote:
Mon Mar 06, 2017 2:06 am
I don't think time slows down the faster you go

of course it does for the outside obsverver.

not the one in the speeding ship of course (to him time speeds up if he observes others,



Noax wrote:
Mon Mar 06, 2017 2:06 am
Speed is not a property of an object,

indirectly it IS - since the mass of an object increases with speed!

mass is a property of an object!


Noax wrote:
Mon Mar 06, 2017 2:06 am
and I can arbitrarily assign any speed to myself without worrying about my watch not keeping proper time. Time slows down for others that have high speed relative to you. So for the twins example, in the frame of the rocket man, time goes slower for his twin that stays on earth, for both legs of the journey since Earth-man is the one with the velocity in both cases. So when does the twin on Earth get so old? It happens when the rocket man turns around! It is simply a redefinition, from rocket-man's new frame, of the time on Earth that is simultaneous with rocket man.
now you are just being silly.

gaffo
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Re: How does time work?

Post by gaffo » Sat Aug 04, 2018 3:47 am

Greta wrote:
Mon Mar 06, 2017 5:13 am
Noax wrote:
Greta wrote:Then again, we're moving through the universe at around 3 million kms per hour, or about 870 kms per second - entities zooming around in near-nothingness as they whirl themselves into existence over time.
Out of curiosity, 870 kms relative to what? I've heard a figure something like that as our velocity towards the so called great attractor, but since our velocity relative to the frame in which the CMB is isotropic (the best guess frame for 'stationary' at a given point in the universe), it is more like the great attractor is coming towards us.
Yes, the Milky Way is said to be travelling at over 2 million km/h, most of the roughly 3 mill https://astrosociety.org/edu/publicatio ... wfast.html. I don't understand about how a relatively uniform CMB means that the Great Attractor is coming towards us. My understanding is that the Great Attractor is the gravitational centre of Laniakea. Exciting stuff - reality at these scales is still a frontier for us.

While our local cluster and The Great Attractor are moving closer together (one way or another), Laniakea too must be moving relative to other superclusters. Still, if the universe is a megacluster of swirling superclusters moving relative to each other, with no discernable relativity outside its expanding bounds, then the space and distances would seem less suggestive of the universe's story than the transformations of its material over time (than the constant movement facilitates).
the scales you are working on must include the expansion of space itself (small but cumulative with distance - where if you look out far enough the distance galaxies are travelling near (even PAST (then they become invisible!) the speed of light).

EXPANSION of SPACE is NOT velocity! those distant galaxies are not higher in mass due to velocity, because their "Velocity" is really just being stationary, riding the Space Expansion Wave (as we are - i.e. when they "over there" are viewing us).

so there is no mass increase nor slowing of time WRT to what you are talking about (which is expansion of space) - and "Faux" velocity that we see per those distance galaxies.

gaffo
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Re: How does time work?

Post by gaffo » Sat Aug 04, 2018 3:57 am

Noax wrote:
Mon Mar 06, 2017 1:51 pm
Greta wrote:Yes, the Milky Way is said to be travelling at over 2 million km/h, most of the roughly 3 mill https://astrosociety.org/edu/publicatio ... wfast.html.
I could not find the 3 million kms reference in there at all.
we can find the velocity (I don;t what it is) of our Milkyway from the redshift of Andromeda (we are in a collision course - will colide in 3.8 billion ys).
knowing the mass of our galaxy and that of Andromeda, and knowing the distance (2.2? million light yrs) - we can figure it out (we can assume there are no other galaxies big and near enough to include in this calculation - whilrpool is the bigges and closest and far enough away to ignore).

there are other relative velocites too!

speed of the Orion Arm (where our sun is), speed of Sol relative to the ave speed of all other start in orion arm.

speed of earth rev around sol.

etc..

gaffo
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Re: How does time work?

Post by gaffo » Sat Aug 04, 2018 4:05 am

Greta wrote:
Tue Mar 07, 2017 5:46 am

When they do separate, they will presumably break apart into smaller clusters that move apart from each other. The prediction is that galalctic clusters will break up but the galaxies will remain intact for some time. They will be so distant from each other, in an otherwise black sky, that any new civilisations in an older universe may well presume their galaxy to be the entire universe.

per current discovery of "Dark energy" expansion of space is accellerating,

eventually even the stars in each galaxy will expand to where eventually earth nigh sky will include only the closest stars - all others in our galaxy will be moving faster than light via space expansion.

the expansion is thought to be non-linear, so by that time it will be not be long when even the sun will be moving too fast from the earth to see it.

the universe will "die" via the "great rip" at that point.

so is the current though on the matter.

14 billion yrs from now.

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Re: How does time work?

Post by Greta » Sat Aug 04, 2018 4:40 am

gaffo wrote:
Sat Aug 04, 2018 4:05 am
Greta wrote:
Tue Mar 07, 2017 5:46 am

When they do separate, they will presumably break apart into smaller clusters that move apart from each other. The prediction is that galalctic clusters will break up but the galaxies will remain intact for some time. They will be so distant from each other, in an otherwise black sky, that any new civilisations in an older universe may well presume their galaxy to be the entire universe.

per current discovery of "Dark energy" expansion of space is accellerating,

eventually even the stars in each galaxy will expand to where eventually earth nigh sky will include only the closest stars - all others in our galaxy will be moving faster than light via space expansion.

the expansion is thought to be non-linear, so by that time it will be not be long when even the sun will be moving too fast from the earth to see it.

the universe will "die" via the "great rip" at that point.

so is the current though on the matter.

14 billion yrs from now.
The great rip is science fiction IMO, akin to suggesting that a growing child will one day grow too big for its skin and explode. The big freeze seems far more likely and credible, which is really many slower "rips".

The Earth is more at risk of being pushed from its orbit by a rogue brown dwarf (as is currently lurking near our solar system) than by dark energy. Of course, due to the Sun's heating as it ages the Earth's surface will largely be uninhabitable in a matter of hundreds of millions of years, and in about five billion years it is expected to fall within the outer layers of what will by then be our expanding red giant star.

gaffo
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Re: How does time work?

Post by gaffo » Sat Aug 04, 2018 4:59 am

Greta wrote:
Sat Aug 04, 2018 4:40 am
gaffo wrote:
Sat Aug 04, 2018 4:05 am
Greta wrote:
Tue Mar 07, 2017 5:46 am

When they do separate, they will presumably break apart into smaller clusters that move apart from each other. The prediction is that galalctic clusters will break up but the galaxies will remain intact for some time. They will be so distant from each other, in an otherwise black sky, that any new civilisations in an older universe may well presume their galaxy to be the entire universe.

per current discovery of "Dark energy" expansion of space is accellerating,

eventually even the stars in each galaxy will expand to where eventually earth nigh sky will include only the closest stars - all others in our galaxy will be moving faster than light via space expansion.

the expansion is thought to be non-linear, so by that time it will be not be long when even the sun will be moving too fast from the earth to see it.

the universe will "die" via the "great rip" at that point.

so is the current though on the matter.

14 billion yrs from now.
The great rip is science fiction IMO, akin to suggesting that a growing child will one day grow too big for its skin and explode. The big freeze seems far more likely and credible, which is really many slower "rips".

The Earth is more at risk of being pushed from its orbit by a rogue brown dwarf (as is currently lurking near our solar system) than by dark energy. Of course, due to the Sun's heating as it ages the Earth's surface will largely be uninhabitable in a matter of hundreds of millions of years, and in about five billion years it is expected to fall within the outer layers of what will by then be our expanding red giant star.
yep, ""we" have a less than a billion yrs. sun's energy will boil water and we will become venus before the red giant shows up.

always laugh when i read posts of "how will man leave the earth before a billion yrs" - hell with genetic engineering/asteriod/evolution of raccoons to a higher level/etc............all orders of magintude before a billion yrs. man wll be long dead before that time.

uwot
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Re: How does time work?

Post by uwot » Sat Aug 04, 2018 6:01 am

Cerveny wrote:
Fri Aug 03, 2018 9:09 pm
uwot wrote:
Fri Aug 03, 2018 1:08 pm
As for your "growth/crystallisation", it's an interesting idea, but how do you account for the observed galactic redshift?
Universe crystallizes from the Future. Vacuum (its history) is an ideal crystal. Elementary particles are some structural defects in it (see screw dislocation, eg). The time of Now is some kind of (live) phase border between the History and the Future. The solid History is just setting, built during a rather accidental quantum interactions (“measurements!?”). Before “Big Bang” was only “Future” - the Platonic’s Empire if Ideas...
Again, it's an interesting idea, but how do you account for the observed galactic redshift?

uwot
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Re: How does time work?

Post by uwot » Sat Aug 04, 2018 7:32 am

gaffo wrote:
Sat Aug 04, 2018 3:33 am
Noax wrote:
Sun Mar 05, 2017 1:36 pm
Time as a coordinate system.
no, that is space.

time is the 4th dimension.
Using three spatial dimensions (from a range of coordinate systems (https://en.wikipedia.org/wiki/Coordinate_system) will enable you to locate any point in the known universe. In order to locate an event, you have to add time. If someone asks you on a date, the address will tell you where it will take place, but if you don't known when the date is, the chances are you won't be able to find it. Three dimensions for a place; four for an event. In fairness, Noax was responding to something I had written, which he had actually read. You can see the context here, page 39 to be precise: http://willijbouwman.blogspot.co.uk
gaffo wrote:
Sat Aug 04, 2018 3:33 am
Noax wrote:
Sun Mar 05, 2017 1:36 pm
Unlike the gravitation field in which a thing finds itself, speed is not a property of a thing,

nope - velocity and gravitiation field have the SAME effect upom matter.

they are the same!
For most practical purposes, it is acceleration that increases the 'weight' experienced by a mass. So if you put your foot down in your car, you get pressed to the back of your seat, and if you go round a corner, you are pushed to the side. If you are going in a straight line at constant speed, you don't feel anything.
gaffo wrote:
Sat Aug 04, 2018 3:33 am
matter increases in mass in both a gravity well and with speed.

same effect.
The gravitational or kinetic energy increases. If you drop a brick on your foot on the moon, it will do less damage than if you do so on Earth, because the lower gravitational potential energy on the moon will convert to lower kinetic energy of the brick. To do the same amount of damage, the moon brick would have to be more massive than the Earth brick. The mass and velocity are different, but the effect is the same. Relativity basically says that it doesn't matter whether the brick is falling, or whether you kick it. (page 28)
Another way of measuring mass is resistance to acceleration. The faster something is going, the more energy you have to give it to achieve the same acceleration. At low speeds accelerating a particle a few mph takes very little energy, whereas at close to the speed of light, you need something as powerful as the Large Hadron Collider to squeeze the same few mph out of a particle.
gaffo wrote:
Sat Aug 04, 2018 3:33 am
Noax wrote:
Sun Mar 05, 2017 1:36 pm
so speed cannot make something happen slower.

again, nope, speed/gravity (same thing) slows time for the object in question.
Well, time as we experience it is just things happening, and they do take 'longer' to happen the faster you are going. The bulk of the chapter on time explains that using Einstein's light clock analogy. Long story short, gaffo, I agree with you on that bit.

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Re: How does time work?

Post by Noax » Sat Aug 04, 2018 1:55 pm

I have to respond to this myself uwot.
Yes gaffo, you've found quite an old post here, and you do like to tell me how wrong I am it seems.
gaffo wrote:
Sat Aug 04, 2018 3:33 am
Time as a coordinate system.
no, that is space.

time is the 4th dimension.
Yes, a 4th dimension (axis) to the coordinate system whose other three axes are space. So I agree except for the 'no' part. Two events in 4-dimensional spacetime have fixed separation regardless of inertial frame, which is the same as saying that two points in a coordinate system (be it 2D, 3D, 4D, whatever) have a fixed separation regardless of the orientation of the axes chosen.
Noax wrote: Unlike the gravitation field in which a thing finds itself, speed is not a property of a thing,
nope - velocity and gravitiation field have the SAME effect upom matter.
I didn't say what effect speed had. I said speed wasn't a property of a thing. What is your current velocity? Can't answer coherently without a reference to something else, which makes it a relation, not a property.
gaffo wrote:
Sat Aug 04, 2018 3:33 am
Noax wrote:Speed is not a property of an object,
indirectly it IS - since the mass of an object increases with speed!

mass is a property of an object!
If I have all these different masses in different inertial frames, all without actually changing my trajectory, then mass is variable, and not a property at all. What is a property of an object is rest-mass. That is a frame independent value for any object, and thus a property. If a value (like mass or speed) is indirectly a property, then it isn't really a property, but a relation with, in this case, a reference frame. That's what I am trying to say. I consider an objects properties to be things that do not vary depending on reference frames.
matter increases in mass in both a gravity well and with speed.
Mass (not matter, which is not a physical quantity) increases with speed, but since speed is not a property, the amount of mass of a thing can still be a fixed property of the thing. Two identical objects might have massively different velocity vectors, but since speed is not a property of either of them, neither is the one that actually masses more than the other.
Noax wrote:so speed cannot make something happen slower.
again, nope, speed/gravity (same thing) slows time for the object in question.
OK, carelessly worded on my part. If it has speed, clearly it is being referenced from a frame in which it has speed, and in that frame, yes, its processes are dilated. But in the frame of the object itself, it is the rest of the universe (anything not moving along with the object) that slows down.

light travelling in space will give you zero time.

so nope, you are wrong.
Light speed is not a valid reference frame. Speed of light is c in any frame. You're attempting to make light stationary, but light cannot be made to do that. What velocity would a photon going the other way have?
Noax wrote: Two events (one of a pair of twins saying goodbye to the other as he boards the rocket, and the event of their subsequent reunion) are separated by different amounts of time depending on the path taken. The path with excessive spatial displacement requires less time displacement to connect the two events. This is unintuitive since it seems to violate euclidean geometry, but so does the gravity thing, so Euclid was already out the window.
gravity wells will give you the result.

you left that out.
No I didn't. I made it bold so you'd see it. The twins are not going to age noticeably different due to the gravity well of anything in our solar system. To illustrate that, you'd have to do something like they attempted to depict in Interstellar, however implausible. The planet they depicted was for one thing waaaaay inside the Roche limit and cannot exist, especially with water on it.

As for the twins experiment, it can be done with only SR rules if instantaneous velocity changes can be made, but gravity is simply not part of SR, so the experiment assumes no significant gravitational objects come into play. I've sort of written an illustration of it with no acceleration at all, but instead using tag teams, and keeping it down to minutes, not years. I'll post it if you want to tell me how wrong it is.

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Re: How does time work?

Post by Noax » Sat Aug 04, 2018 7:19 pm

uwot wrote:
Sat Aug 04, 2018 7:32 am
Another way of measuring mass is resistance to acceleration. The faster something is going, the more energy you have to give it to achieve the same acceleration.
Hate to disagree, but this seems misleading. Acceleration is a function of force and mass, not energy. F=mA, or A=F/m. So for instance the ISS accelerates at all time due to the force of gravity on it, yet no exchange of energy is involved. In frames where the object has relativistic speeds, the same force results in less acceleration because it is resisted by more mass. Newton's F=mA still works in under relativity. Energy again is not a factor. Kinetic energy is completely frame dependent and thus not really a property of anything.
At low speeds accelerating a particle a few mph takes very little energy, whereas at close to the speed of light, you need something as powerful as the Large Hadron Collider to squeeze the same few mph out of a particle.
The LHC needs all that energy because the particles get so massive in the frame of the LHC, and in addition, most of that force generated by the energy expenditure is wasted getting the particle to turn and not so much getting it to speed up. The larger the radius, the more force can be devoted to speed and less to turning. Still, the round ones get more speed than do the linear ones. I guess total travel distance makes more of a difference than does the percentage of force that is not orthogonal to the particle's velocity.

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