## Time dilation

• 980
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
• 3.2k
You mean the force of gravity. Yes, that is pretty much everywhere.
• 475
You mean the force of gravity. Yes, that is pretty much everywhere.Rich
No, I mean the force of the "Spaceship engines".
• 3.2k
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.
• 1.1k
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.
• 3.2k
• 1.1k
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.
• 3.2k
Where in the equations does it talk about biological aging?
• 1.1k
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.
• 980

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
• 3.2k
Right. Trust them scientists ... to exaggerate all claims.
• 980

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

.
• 980
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
• 3.2k
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.
• 980

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
• 3.2k
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.
• 980
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
• 3.2k
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.
• 102

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.
• 3.2k
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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