## Time dilation

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Fine. While you are waiting, why don't you do some reading also.Rich

Just check your facts before you post. It will result in a smoother and more peaceful discussion. You're getting aggressively-assertive, when you're mistaken. Surely you want to avoid that.

In general, it's best to stay civil.

Michael Ossipoff
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You mean the force of gravity. Yes, that is pretty much everywhere.
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You mean the force of gravity. Yes, that is pretty much everywhere.Rich
No, I mean the force of the "Spaceship engines".
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What spaceship engines. The people on Earth don't see any spaceship engines. They only see that they are accelerating away from the little spaceship.

The spaceship person is in a coma.

Sorry, you can't stick spaceship engines in the equations. But I'll double check.
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Sorry, you can't stick spaceship engines in the equations. But I'll double check.Rich

What equations are you talking about? Are you making any use at all of the Lorentz transformations (as you should?) In that case you surely should be aware that those equations apply to space and time coordinates as measured in *inertial* reference frames. The reference frame in which the Earth remains at rest and the reference frame in which the travelling rocket remains at rest can't both be inertial frames since there is a relative acceleration between them. So, you have to think again how you might be misusing the equations of special relativity to apply to accelerating reference frames.
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GTRRich

So, you are making use of the equations of the General Theory of Relativity? Those equations are Einstein's field equations. They will tell you how to relate the metric tensor (that describes the geometry of space-time) to the stress-energy tensor (that describes the density and flux of energy and momentum in space-time). From this, is should appear that the people who remain on Earth have a space-time path that follows closely a space-time geodesic (and might follow it even more closely if they were orbiting the Earth in 'free fall' rather than resting on its surface) while the travelling twin follows a path that deviates very sharply from this geodesic (because of the rockets). When you integrate the proper-time along the space-time path of the traveler, you should find out that this proper-time is shorter than the time elapsed along the path followed by people who stay on Earth.
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Where in the equations does it talk about biological aging?
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Where in the equations does it talk about biological aging?Rich

They don't because they're equations of physics and not biology. But they do tell you how much time will be elapsed on Earth, and on the ship, as measured by any clock that is governed by physical processes such as, say, an atomic clock or a clock based on local measurements of the travel time of a pulse of light. There is no reason, though, why there would be a mismatch between the rates of typical biological processes and the rates of the underlying physico-chemical processes that they normally are correlated with.
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What I meant to say was just that modern physics--general relativity, quantum mechanics, etc. is really a complicated, involved specialized subject, and one best left to its specialists.

Only a physicist, or maybe someone advanced in a physics curriculum will know what's going on at the frontiers of physics, what those subjects are about. There's really no point in our debating those matters here.

Michael Ossipoff
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Right. Trust them scientists ... to exaggerate all claims.
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After my previous post, I should emphasize that, though I don't know general relativity, I'm sure that many would agree that Pierre-Normand sounds like he knows what he's talking about. So I didn't mean to claim that no one here, or in this discussion, knows modern physics. .

I just meant that it's just a subject that few people are qualified in, even if a there are a few here who are.

Michael Ossipoff

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Right. Trust them scientists ... to exaggerate all claims.Rich

A lot of scientists understandably believe that science explains everything. You can't blame them. They've mastered a very complicated and difficult subject, and it's natural to have a feeling that it's everything.

Certainly not all--but some--scientists are Scientificists (Science-Worshippers). Of course a lot of people who aren't scientists are Science-Worshippers too.

You, Rich, have accused me of being one (a Science-Worshlpper, not a scientist). I'm not. All Science-Worshippers are Materialists (aka "Naturalists". ...and sometimes "Nominalist" is used to mean effectively the same thing as "Materialist"). I'm not a Materialist. You've heard my metaphysics.

But where you, Rich, are making a mistake is to not accept that scientists are right about their own field,

I personally feel that Western academic philosophy is bullsh*t, but physicists and other scientists are experts in an objective and solid subject, even if a few take it outside its legitimate range of applicability and claim that the material world that they study is all of Reality.

Michael Ossipoff
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You can't blame them.

Of course I can. They are subject to greed and over self-aggrandizing like any other human, maybe even more because the stakes are higher. It's not as it it is Determined that they should exaggerate by some Laws of Physics. They do it because of who they are. There are BS artists in every field, and the best get the most money and most advancement. That is the nature of industry. Money is what counts.
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Sure, there are a small minority of scientists who have allowed themselves to be bought, and hired to say that there's no human-caused climate change. Likewise the cigarette companies never found a lack of purchasable scientists to publish favorable studies about cigarettes.

But those are the exceptions. Only a very tiny minority of scientists are on the industrial climate-denial payroll. Scientists are nearly entirely unanimous about the impendiing human-caused climate disaster.

Michael Ossipoff
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But those are the exceptions

There are many forms of exaggeration (even in the pop books) and most everyone just goes along with it because why put their neck out on the line. Anyone who protests is quickly ejected. No different than any profession where big money is at stake. Hear no evil, speak no evil, see no evil. Just pretend it's not happening.
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There are many forms of exaggeration (even in the pop books) and most everyone just goes along with it because why put their neck out on the line. Anyone who protests is quickly ejected. No different than any profession where big money is at stake. Hear no evil, speak no evil, see no evil. Just pretend it's not happening.Rich

Sometimes it seems to me that there's a bit of exaggeration of science's needs and goals. Though I'm not anti-science, I don't support everything science does.

I opposed the Large Hadron Collider (LHC). I oppose the Parker solar probe (It's scheduled to be launched this year). I oppose the Nazi-esque harmful medical experimentation and product-testing on live animals.

Michael Ossipoff
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A reasonable and practical way of understanding science is to recognize it as a giant industry being driven by desire for money where most participants just "go along". The exaggeraters are placed in key sales, fund-raising, marketing, and management positions. They do what's necessary to bring the money in. No different than any other industry.
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Time dilation is a real observable and measurable phenomena. Time dilation is seen in both special relativity (relative motion) and general relativity (gravity or acceleration) .
In fact the GPS system would be worthless were the effects of time dilation on the clocks in the satellites not taken into account. In this instance general relativity (gravity) effects dominate.

Depicts the time dilation as a function of orbital height relative to a stationary observer on earth. The total dilation is due to two distinct effects: Special relativity accounts for slowed time in orbit (relative to the observer on earth) depending on the orbital velocity associated to a specific orbital height. General Relativity accounts for accelerated time (relative to the observer on earth) due to the distance to the earths gravitational center. This depiction simplifies by assuming circular, equatorial orbits without inclination, upon which special relativity is weakly dependent.
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Time dilation is a real observable and measurable phenomena. Time dilation is seen in both special relativity (relative motion) and general relativity (gravity or acceleration) .
In fact the GPS system would be worthless were the effects of time dilation on the clocks in the satellites not taken into account. In this instance general relativity (gravity) effects dominate.

All this says is that clocks are affected by gravity. I'm not surprised. But this has nothing to do with duration of life. This is what Bergson and others reject, i.e. that clock measurements have anything to do with experiences biological life. To make matters worse for Relativity, STAR head no place in reality and GTR had no place for very time (as we know it). However the kinds of leaps in imagination that science is well-known for. Scientists just get carried away. A few neurons moving and they discovered everything about mind.
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Clocks run based on physical principles. In the case of atomic clocks on the emissions of atoms. If the physical process on which the clocks keep time is slowed by gravity there is little reason to think the chemical processes, biochemical processes and other processes of life are not correspondingly slowed as well since they all are dependent on the underlying physical processes. The burden of reason and proof would be to explain why they would not correspondingly slow. Einstein had a great deal to say about clocks and measuring rods albeit time itself is another matter. For me time is just an abstraction from change, not any independent, absolute or fixed entity. So the fact that clocks run at different rates under acceleration or gravity seems unsurprising. What is surprising would be to think that if physical processes are slowed, chemical and biological process would not also be slowed.
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Clocks run based on physical principles. In the case of atomic clocks on the emissions of atoms. If the physical process on which the clocks keep time is slowed by gravity there is little reason to think the chemical processes, biochemical processes and other processes of life

You just made the same error of equivalence between physical process and the process of duration which by nature is continuous and heterogenous. Where in GTR are there explanations for the experience of duration as we are daydreaming or sleeping? The experience of living is not ruled by clock measurements.

This is an example of getting carried away and jumping to all kinds of assumptions. We create clocks to measure simultaneity and then all of a sudden, out of no where, our experience of existing depends on it. Not so fast.

As a matter of observation, the human body which is under constant acceleration, just lives. If placed under extreme forces it will die. As for the Mind, I don't know, but I do speculate.
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Not that facts, science or even empirical data seems to matter to you on this subject still the evidence is clear, and no alternative rational explanation is being offered.

There are several direct proofs of time dilation. Extremely accurate clocks have been flown on jet aircraft. When compared to identical clocks at rest, the difference found in their respective readings has confirmed Einstein's prediction. (The clock in motion shows a slightly slower passage of time than the one at rest.)

In nature, subatomic particles called muons are created by cosmic ray interaction with the upper atmosphere. At rest, they disintegrate in about 2 x 10E-6 seconds and should not have time to reach the Earth's surface. Because they travel close to the speed of light, however, time dilation extends their life span as seen from Earth so they can be observed reaching the surface before they disintegrate.
Answered by: Paul Walorski, B.A., Part-time Physics Instructor

In October 1971, Hafele and Keating flew cesium-beam atomic clocks, initially synchronized with the atomic clock at the US Naval Observatory in Washington, D.C., around the world both eastward and westward. After each flight, they compared the time on the clocks in the aircraft to the time on the clock at the Observatory. Their experimental data agreed within error to the predicted effects of time dilation. Of course, the effects were quite small since the planes were flying nowhere near the speed of light.
Such time dilation has been repeatedly demonstrated, for instance by small disparities in a pair of atomic clocks after one of them is sent on a space trip, or by clocks on the Space Shuttle running slightly slower than reference clocks on Earth, or clocks on GPS and Galileo satellites running slightly faster.[1][3][4
• In 1959 Robert Pound and Glen A. Rebka measured the very slight gravitational red shift in the frequency of light emitted at a lower height, where Earth's gravitational field is relatively more intense. The results were within 10% of the predictions of general relativity. In 1964, Pound and J. L. Snider measured a result within 1% of the value predicted by gravitational time dilation.[31] (See Pound–Rebka experiment)
• In 2010 gravitational time dilation was measured at the earth's surface with a height difference of only one meter, using optical atomic clocks.[20]
• Hafele and Keating, in 1971, flew caesium atomic clocks east and west around the earth in commercial airliners, to compare the elapsed time against that of a clock that remained at the U.S. Naval Observatory. Two opposite effects came into play. The clocks were expected to age more quickly (show a larger elapsed time) than the reference clock, since they were in a higher (weaker) gravitational potential for most of the trip (c.f. Pound–Rebka experiment). But also, contrastingly, the moving clocks were expected to age more slowly because of the speed of their travel. From the actual flight paths of each trip, the theory predicted that the flying clocks, compared with reference clocks at the U.S. Naval Observatory, should have lost 40±23 nanoseconds during the eastward trip and should have gained 275±21 nanoseconds during the westward trip. Relative to the atomic time scale of the U.S. Naval Observatory, the flying clocks lost 59±10 nanoseconds during the eastward trip and gained 273±7 nanoseconds during the westward trip (where the error bars represent standard deviation).[35] In 2005, the National Physical Laboratory in the United Kingdom reported their limited replication of this experiment.[36] The NPL experiment differed from the original in that the caesium clocks were sent on a shorter trip (London–Washington, D.C. return), but the clocks were more accurate. The reported results are within 4% of the predictions of relativity, within the uncertainty of the measurements.
• The Global Positioning System can be considered a continuously operating experiment in both special and general relativity. The in-orbit clocks are corrected for both special and general relativistic time dilation effects as described above, so that (as observed from the earth's surface) they run at the same rate as clocks on the surface of the Earth.[37]

The time that clocks are measuring is not divorced from the physical process underlying the measurement. In fact time is just an abstraction from the underlying physical process and change. It is the physical process which is slowed and correspondingly chemical and biological process are slowed. Admittedly the conclusions arising from modern physics, relativity and quantum physics run counter to our everyday intuitive sense of space and time but nonetheless no more compelling theory to explain the evidence and observations is currently available and talking about Henri Bergson and his conception of "duration" just does not provide an explanation for the observed facts.
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Not that facts, science or even empirical data

When they accelerate a person to the speed of light, let me know what happens.

What I object to it's flight of fantasies replacing actual observations. You keep substituting clocks for life. Gross misrepresentation of the experience of Life. Duration cases for me when I am unconscious, clocks keep ticking. BIG difference. Clock time is not life (real) time - the time of duration. Why all the substitution? Because science doesn't have the foggiest notion about the nature of Life, so it substitutes dead matter. That will get someone far.

Too much fantasy in science nowadays. Neurons are minds. Time is clocks. Drugs are healthy. What a mess.
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I will give you the last word, not because that post makes sense or explains any observation or fact but because further discussion on the subject seems unlikely to yield any meaningful exchange. Although I agree that scientific observations and physical empirical measurements do not explain everything, they are a good starting point for deeper insights into the true nature of space-time and any rational theory or metaphysics must account for science as well.
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hat scientific observations and physical empirical measurements do not explain everything, they are a good starting point for deeper insights

About measuring dead things, that is all. Einstein (actually, it was probably his wife) used some crazy mathematics to describe the effects that gravity has on measurements and matter and thanks to some Sci Fi writers, bingo, bango, it becomes a new ontology about the nature time. How's that? It has zero to do with life and duration. Never was meant to, never will be. Time (the time we experience and feel) is not in any equation. That it is, is called flight of fantasy.

Life is the providence of itself, the experience of Life is that if the Observer, and substituting dead things or symbolics for the nature of Life will get someone no where except utter confusion. Zeno demonstrated this in a most amusing way.

If someone is accelerated, the physical life will die and I can only speculate what will happen to the mind. But whatever it does, it certainly will have nothing to do with ticking clocks.
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I do not think you can disconnect life from the biology, chemistry and physics which underlie it, in that way. From my point of view it is your elevation of life as something completely different from or entirely beyond science that is the "flight of fantasy" and "divorcement from reality". As for time, time does not really exist except as the change, flux or becoming that is the essential nature of the world. "Duration" is just a word with no objective meaning.
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biology, chemistry and physics which underlie it,

There is the point of view that inevitable leads to fantastical conclusions as reached by over zealous readers of Relativity. What started out as some mathematics to explain compare and transform measurements becomes - without even a single breath of reelection - a full blown ontology. Welcome to the world of Sci Fi time travel. The Mind created mathematics, chemistry, physics, and all other sciences, not the other way around.

Duration is what we all experience as life. Forget the clocks. They are limited tools for attempting to establish simultaneity of events. Nothing more. People are so apt to get carried away but a good Sci Fi story. Stories are fun and easily contrived. Understanding life takes - a long, long time.

BTW, science as an industry, is about as far away from objectivity as anything can be. In anyway, case, objectivity if science is just another one of those myths for those who like to believe in objectivity.
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So now we have mind without brains and life without physical bodies, soon we will be back to "souls", animism and the "elan vitale" as if they suffice to explain much. Not that I am opposed to views that go beyond science just that I find views that reject science in that manner severely handicapped in terms of rational or meaningful discussion. Philosophy being rational discussion and speculation.
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You appear to be the Kelley-Ann Conway of talking about relativity. Free speech has its limits, if you're just a troll. Keep trolling and I myself will request you be banned.
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