1

Physics, Astronomy & Cosmology / Re: Why can't i understand the andromeda paradox?

« on: Yesterday at 01:48:46 »

I'm sorry but maybe you do have a subscription to PBS or NOVA or whatever it is.   I get asked to type in my log-in details, skipping or closing that and you get  ...

Funny, I had no trouble, even back when the link was first posted. It asked for my email, but I dismissed that and the video was there.
It's a good visual aid, but nothing above and beyond so to speak.
They use a loaf of bread to represent spacetime and then slice it a different arbitrary 'angles of simultaneity'.
Then it illustrates the implications of that using something like the Andromeda paradox, except from the point of view of the distant alien (on a bicycle) rather than using our PoV. I like that variation since I think it drives the point home better.

2

General Science / Re: Atom?

« on: 19/03/2023 13:49:14 »

Is an Atom still Indestructible?

Technically, all you have to do is heat it up quite a bit (or put it in a strong electric field as mentioned above).
At a certain temperature, it turns to plasma, kind of like boiling turns liquid into gas. Plasma is the same element but with the electron stripped away, and a nucleus without its electrons is no longer an atom. But let it cool and the atom will reform.
Splitting an atom (decay, fusion, violence, whatever) is more permanent and the original atom is gone.

3

New Theories / Re: If there was one Big Bang event, why not multiple big bangs?

« on: 14/03/2023 19:22:36 »

I don't believe there is any irrefutable evidence though that says there was a beginning

There indeed is no irrefutable evidence of it. The big bang theory itself does not preclude it, but neither does it give any meaning to the phrase 'before the big bang'.

4

Physics, Astronomy & Cosmology / Re: What do you consider the most disappointing discovery in space exploration?

« on: 09/03/2023 14:47:58 »

Far more disappointing was the discovery that Earth was not the center of the universe and that our significance in that universe was negligible, the complete opposite of what everybody presumed for such a long time.

The face on Mars is not a mirage. A mirage is something that is really somewhere else. It is a play of shadows, something that is really there, but only looks like that in just a certain light. If that's somebody's biggest disappointment, they need bigger expectations.

5

New Theories / Re: If there was one Big Bang event, why not multiple big bangs?

« on: 09/03/2023 07:12:04 »

I do recall that just few years ago, Halc claimed that Just after the Big Bang the entire Universe was in the size of a grapefruit. (I specifically remember the word - "grapefruit")

Too bad you didn't remember the other important words. It was the visible universe, and it was approximately that size (give or take an order of magnitude or two) after the inflation epoch, which came after the Planck epoch and Grand Unified epoch.

When I have asked about the energy source for the Big Bang, the answer was: As there was no space and no time, there is no need to explain the BBT energy source.

I would not have said that. For one, it is unclear if there is any energy since the total energy density of the universe may be zero if you add in the negatives with the positives. But I think if you ask the experts, the concept of total energy density is meaningless. It's all relative, not absolute, so there's only comparisons with other states.

Therefore, the time was ticking long before the Big Bang moment.

I would ask you to confine your assertions to your own topics. You're hijacking this topic, and continued wild assertions will get the posts moved or simply deleted.
This particular assertion seems to be an exception because Bogie already envisions bangs happening in existing space at assorted times now and then. This cannot work, but he doesn't care.

Other assertions (like the confusion of scientists or the uselessness of their theories) will get treated as a hijack. So behave when being a guest in somebody else's blog.

6

New Theories / Re: The Proper Separation of the Clocks Doesn't Change!

« on: 06/03/2023 17:38:10 »

The Proper Separation of the Clocks Doesn't Change!

By definition, yes. If the separation is changing (such as in the examples in recent posts including this one), then each of the objects is moving relative to the other, and therefore have no proper separation since there's no frame in which both are stationary.

Anyway, thanks for posting in New Theories.

Two perpetually inertial observers (IO1 and IO2), perpetually mutually stationary with one another, are initially co-located with two separated observers (AO1 and AO2), with separation "L". AO1 and AO2  are about to begin a constant [proper] acceleration "A"
...
 IO1 and IO2 will conclude that AO1 and AO2 maintain the separation "L" during the accelerations.

This seems to be how you specify an inertial frame reference, in this case frame S (using Einstein's name since you won't name it). Yes, the accelerating objects will maintain constant separation in that frame, but since they're both moving in that frame, it isn't proper separation.

And AO1 and AO2 will agree with that: AO1 and AO2 conclude that their separation remains constant at "L" during the acceleration.

And here you fall apart. They might agree that they're the same separation relative to S, but they didn't say 'relative to S' (or any other frame) so the statement is meaningless at best, and wrong if they're talking about any frame in which one or the other might be momentarily stationary.
If you suggest an accelerating frame, you need to specify which kind since there are several. Rindler coordinates are typical, but those coordinates are not the one Einstein uses.

The distance "D" each rocket moves, according to AO1 and AO2

Distance relative to what? S? Say that then. This cannot be computed without making a frame selection. AO1 has moved nowhere according to AO1 since he started out 'here' and is still 'here' after any amount of time, so in any traditional frame with the observer at the origin, that distance is zero.

The distance "D" each rocket moves during the acceleration is EXACTLY the same

Relative to what? Your confusion mostly stems from refusal to specify frames. The distance each rocket moves relative to the other is certainly not the same.

so the separation "L" between AO1 and AO2, according to THEM, can't change during the acceleration.

Your title say 'proper separation'. You've not computed that at all, and cannot since there is no proper separation between things moving relative to each other.
You seem to be computing separation relative to S, which is trivially constant. But that's not the frame of either accelerating object. Also, don't assume the frame of one object is the same as the other which cannot be the case when the objects are not stationary relative to each other.

Your case this time doesn't suggest that the acceleration ever stops. Just asking to see if the scenario is changed from last time. I also notice you provide no numbers, no coordinates of where everything is in certain frame at certain events. I provided that in my answers, but you never do. Work the numbers and the mistakes will become obvious, and you don't have to keep asking via forum posts if your assertions work. Try working it out with numbers instead of making the assertions in the first place.

But two inertial observers (IO3 and IO4) who are momentarily co-located with AO1 and AO2 at some later instant in the trip will conclude that the separation between AO1 and AO2 is LARGER than it was when the acceleration started.  And that larger separation continues to increase as the trip progresses, according to the INERTIAL observers momentarily co-located with AO1 and AO2 later in the trip.

This statement sort of indicates that 'according to AO1' at some event has totally different values than 'according to some comoving inertial observer at the same event'. In that case, I have no idea what coordinate system AO1 might be using. You seem to have no idea either.

But it's normal in special relativity for an accelerating observer to agree with the inertial observer who is momentarily co-located with him at at some instant ... that's what the CMIF simultaneity method IS.

That's not what the rest of the world calls it, but yes. So apparently AO1 is not using what you call CMIF method, but you won't say what he's using instead.

How do the people producing the scenario with all the inertial observers achieve the acceleration "A"?

I don't see how any inertial observer can achieve acceleration at all.

Mike, I'm going to continue to rip on your posts as long as the frame references are absent. You mention 'according to X' sometimes, but then makes statements that are not true in frames where X is stationary, so it gets pretty unclear what 'according to X' means without specification of what coordinate system X is using.

7

New Theories / Re: A Proposed Experimental Test of My Gravitational Time Dilation Equation

« on: 03/03/2023 06:08:47 »

The leading observer does NOT consider the stopping time to be tau on HIS watch  But he DOES expect the trailing clock to read tau when they stop

Now you've changed the story. Post 5 (where you first describe this particular case) is pretty clear that the lead clock stops accelerating when its own clock reads tau:

and who then simultaneously start accelerating (according to their accelerometers) at a constant "A" ls/s/s
...
In each of the cases, the acceleration "A" and the duration "tau" of the acceleration are chosen such that the product "A tau" is constant for all cases at 1.317 ls/s.  That results in all cases in the velocity of the two clocks, at the end of the acceleration, being 0.866 ls/s.

The proper acceleration is specified to be the same for both objects, and the resulting rapidity (1.317c) or speed relative to S (0.866c) is identical for both, which cannot happen if the lead object accelerates longer than tau as measured on its own clock.

Second problem is that the lead observer is not in the presence of the rear clock, so the moment that the remote clock reads tau is frame dependent, and you refuse to specify a frame.

Third problem is that for something accelerating (in the first case) at 31˝ million g, in the inertial frame in which the front observer is stationary (what you call his CMIF), the rear clock is always unaccelerating since time moves backwards for it. So by your specification above, and assuming you're using the front observer's own CMIF (you never say), the condition of the read clock reading tau will never occur.

Get your story straight Mike. Use frame references. I tire of pointing out your mistakes only to have you move the goal posts into a new but still inconsistent story.

A "NOW-at-a-distance" instant, according to these two accelerating observers, consists of any arbitrary instant "t" in the life of the trailing observer, and the corresponding instant

  t * exp(L*A)

OK, can you identify the frame in which this is true? The event of the rear clock reading 1 second and the second event of the front clock reading ~5˝ hours (from 1st line of your table) can be made simultaneous by selection of an inertial frame where neither observer is stationary. Do you want to use that one? The clocks will be an awful lot further apart in that frame than just L after the front one shoots off at 31 million g for several hours.

8

New Theories / Re: A Proposed Experimental Test of My Gravitational Time Dilation Equation

« on: 28/02/2023 15:03:05 »

You quote a statement of mine denying the fact that you've proven something about Einstein's equation, but then you post stuff irrelevant to that demonstration. You seem focused on a different scenario than the one Einstein describes.

I told you what I got in the sequence of calculations (for the HF's age at the end of the acceleration) for each of my choices of the acceleration "A" and the duration of the acceleration "tau" (such that the velocity change is the same in each iteration of the sequence).  Clearly, in my calculations, the sequence was NOT converging to a finite limit ... the HF's age was clearly going to infinity as tau goes to zero

Your calculation is dependent on the arbitrary coordinate system you choose to make such a measurement. You consistently refuse to specify this, but I'm guessing the inertial frame of all objects after all accelerations cease. And yes, your accelerations cease in your scenario.

That results in all cases in the velocity of the two clocks, at the end of the acceleration, being 0.866 ls/s.

This is important because Einstein did not specify this. His scenario involves eternal acceleration of all objects once they start. He also isn't computing ages using any inertial frame since nothing is inertial.

and that is inconsistent with the outcome of the twin paradox.

If course it is. The twin paradox is Case T, not Case B. It involves only one entity accelerating, not both of them. This is what I mean by you attempting to use formulas of one scenario with the wrong scenario.

If you think my calculations are wrong, what do YOU get when you do that sequence of calculations?

I went straight for zero duration, an instant change of velocity of all objects to .866c, then did a simple Lorentz transform. Relative to the new inertial frame of the rear clock (which still reads 0), the front clock now reads just over 13 seconds, and is just over 15 ls distant, exactly twice its former distance (relative to the inertial frame in which they were stationary before the velocity change) of 7.52. Both clocks are stationary in this new frame after the rear clock does its acceleration.

If you're going to say my calculations are wrong, you need to show what the correct calculations are.

Well, I didn't actually see any calculations. But infinite seems wrong in most plausible coordinate systems I can think of.

The results of my calculations, in Section 3 of the above referenced paper, are given in a table near the end of Section 3.

If it isn't posted here, I don't see it. I don't do links to personal material.

The exponential GTD equation says that the leading clock tics faster by the factor exp(A*d).  And so the change in the reading on the leading clock, during a time interval "tau", is just tau * exp(A*d).

Well, by definition, during the proper interval tau, any clock advances by exactly tau. You're probably talking about 'as measured by something not in the presence of the clock in question', but for that to have meaning, a coordinate system needs to be specified. In any one inertial coordinate system, if zero time has gone by, then all clocks advance by zero seconds regardless of their motion or acceleration rates. So either you're changing frames without specifying such an action, or you're choosing a non-inertial frame. Your refusal to do this renders all your conclusions meaningless.

In Einstein's 1907 paper, https://einsteinpapers.press.princeton.edu/vol2-trans/319 , he gives his exponential gravitational time dilation equation.  Actually, he was working a special relativity problem (with accelerations and no gravitation) because he knew how to do that, and he was hoping the result would give him (via the equivalence principle) some help in his search for a gravitational theory.  So Einstein's equation was actually a time dilation equation for accelerating clocks that are separated by a fixed distance.  According to Einstein, for a pair of accelerating clocks separated by the distance "L" in the direction of the acceleration, the leading clock tics faster than the trailing clock by the factor

  R  =  exp(A*L),

where "A" is the acceleration.  In the iterations described below, I will limit myself to the case where "A" is constant during the acceleration.  I will show that the exponential time dilation equation is incorrect.  (I suspect that Einstein, and also physicists who came along later, didn't ever notice that the exponential equation is incorrect, because they never used it in the nonlinear range where its argument is large ... they only used it for very small arguments, where it is very nearly linear.)

Every bit of the above is rubbish, and just a repeat of the assertions made in earlier posts (mostly meaningless assertions given the still absent frame references), all of which have been refuted, and without response to the refutations. I'll not bother doing it again, but rather comment on the remaining bit.

Suppose that the two clocks are initially inertial (unaccelerated) at time "t" = 0, and both read zero at that instant.  Then, for t > 0, both clocks undergo a constant acceleration "A" (as determined by accelerometers attached to each of them, which control a rocket attached to each of them, so as to achieve the specified acceleration).  Their separation remains constant at "L" during the acceleration.  In all of my calculations below, I chose L = 7.520.  Let "tau" be the duration of the acceleration.
Therefore the reading on the leading clock, when the trailing clock reads "tau", is given by
AC  =  tau * R  =  tau * exp(A*L) .

That cannot be true. For one, you have a self-contradiction going on. If the lead clock 'tics faster' as you put it, it will finish its tau-seconds of acceleration first, meaning there will be a period of time where one ship is accelerating and not the other. This contradicts your assertion (that Einstein certainly doesn't make) that the separation distance remains constant. Anyway, the formula you give will not in any way give the reading on the leading clock, when the trailing clock reads "tau". I did that above (the number approached as acceleration increases without limit) and got about 13 seconds. You don't seem to suggest a different figure, only giving a demonstration that the formula above isn't going to give the right answer, which it indeed doesn't.

So we get the following table:
  tau            AC
  1.0       2.0 * 10^4
   0.1      1.0 * 10^42
   0.01    1.0 * 10^428
Clearly, this iteration is NOT approaching a finite value for the leading clock's reading, as tau goes to zero.

Indeed. They're also all wrong since the right column should decrease from about 14 down to 13, and not those huge numbers. What do you suggest are the correct values? I notice you don't work that out. Are my numbers wrong?

So when we use this method to determine by how much the home twin's (her) age increases when the traveling twin (he) instantaneously changes his velocity by 0.866 when he reverses course at the turnaround it tells us that the home twin gets INFINITELY older, which is not true.

Correct again.You seem amazed that using a perfectly good formula for an inapplicable situation gives wrong answers. What were you expecting?

From the time dilation equation for an inertial observer (which the home twin IS), we KNOW that both she and he have a finite age at their reunion.  Therefore the exponential gravitational time dilation equation CAN'T be correct.

Wrong conclusion, twice. 1, That formula has nothing to do with gravity. 2, it also has nothing to do with either your scenario with the decreasing tau  or the twins scenario with only one clock accelerating. It is for a different scenario, one that you've never considered. If you read Einstein's paper (or my posts above), maybe you'd notice that.

9

New Theories / Re: If there was one Big Bang event, why not multiple big bangs?

« on: 28/02/2023 03:57:47 »

current Standard Cosmology, which I understand depicts finite space to be expanding

Current models do not posit finite space, but neither do they require infinite space. Most models presume space to be infinite.

My question is, does the BB model refer to the action going on at the expanding boundary of the universe as creating space and matter out of nothingness?

No viable model posits a boundary to space, not even the ones with finite space.

is it consistent to predict that  anti-space or negative space, and anti-matter are building up and exist beyond that expanding universe, in a sort of anti or negative universe?

There is no meaningful 'beyond space'. There might be other universes, but there wouldn't be a meaningful say direction in which they might be. If there was, it would just be a different but distant part of the same space. A type-1 multiverse is exactly that: Just locations in our space too distant to measure from Earth.

10

Physics, Astronomy & Cosmology / MOVED: Accelerated Clocks: A Meaningful “NOW-at-a-Distance”

« on: 26/02/2023 01:37:17 »

This topic has been moved to New Theories.

https://www.thenakedscientists.com/forum/index.php?topic=86142.0

Primary reasons for move is that this is not a question, but rather evangelism of papers being promoted on multiple sites, despite being shown to contain errors

11

Physics, Astronomy & Cosmology / Re: How Do We Know The Universe is 13.8B yrs Old If We Can Only See The Observable ?

« on: 25/02/2023 15:32:25 »

How can we know it is 13.8 billion years old if all we can see is the observable Universe ?

The age was not computed by looking as far as we can see. Hubble's constant of about 70 km/sec/Mpc was measured nearly a century ago, long before they were looking at things a significant percentage of the distance to the edge of the observable universe. The age can be computed directly from just that one constant.

There's about 3e19 km in a Mpc, so 70 km/sec/Mpc is the same as 2.3e-18 km/sec/km which, cancelling the km part, is 2.3e-18 sec^-1
The reciprocal of that is 4.35e17 seconds which is 13.8 billion years.

12

Geology, Palaeontology & Archaeology / Re: What is the 26 second pulse of the Earth ?

« on: 24/02/2023 17:19:16 »

One thing I was recently made aware of is that the Earth has a 26 second pulse !!!...what's that all about ?

First of all, it seems to originate from a specific spot (somewhere near the Gulf of Guinea), so it's a particular thing that has the pulse, not the whole Earth. Nobody seems to know what it is, but I can take a couple of guesses.

1) It is sort of like regular passage of gas through your guts when you've eaten too much enriched grass all at once. It bubbles at a steady pace. So perhaps this is magma/lava moving from here to there at a steady pace and blooping through a tight spot every 26 seconds. The location is near a know volcanic zone, so that kind of internal movement is plausible.

2) Maybe it's a regular earthquake where two plates scrape nearly effortlessly past each other without getting stuck like most of them do. The result would be like nails on a chalk board except much lower pitch.

For either of those guesses, it seems pretty remarkable that the noise would persist for over half a century, but it has.

13

Physics, Astronomy & Cosmology / Re: If I Throw A Ball From The ISS, Will It Eventually Return From The Other Side

« on: 24/02/2023 16:48:34 »

hrow a ball from the ISS in a way that it will return from the other side ?

Yes, it can be done.

If you throw a ball from the ISS at any time, it will return to the same spot (relative to Earth's inertial frame) each time. Trick is to get both the ISS and the ball to be at that spot at the same time.

Best way to do that is to have both come back after one orbit, which means the ball simply needs to move at the same speed relative to Earth as does the ISS, so just throw it (not hard) almost exactly perpendicular to its motion and it will come back in one orbit, and yes, from the other side.

Another way to to throw it forward really hard into a higher eccentric orbit and get it to orbit once when the ISS takes two trips around. Similarly, one could throw it to the front or rear but no so hard, in which case it will take many trips around before the two sync up, but it will come back always if you wait long enough.

Don't throw it to the rear too hard or it will drop into the atmosphere and konk a poor sheepy on the noggin.

14

New Theories / Re: A Proposed Experimental Test of My Gravitational Time Dilation Equation

« on: 24/02/2023 03:35:26 »

Question for Halc:  All of the above is standard special relativity: it came from Einstein himself.  I have introduced some terminology that I believe clarifies some things, but I haven't changed any of Einstein's results.  Do you nevertheless want to banish it to the "other theories" forum?

You consistently misunderstand both the situation described by Einstein, and also the meaning of the equation in question, so yes, here your post goes once again to this topic where you refuse to respond appropriately (not just with assertions) to errors being pointed out in your posts. You seem to totally disregard peer review, something that a professional physicist would never do.

Another question for Halc: Does the fact that I have found an error in Einstein's exponential equation justify banishing this posting to the "other theories" forum?

You calling it a fact doesn't make it a fact.

Have you tried to confirm or refute my proof?

Yes, I've refuted it. You ignore the errors I point out.

Another question for Halc:  Does the fact that I have derived the correct gravitational time dilation equation to replace the incorrect exponential equation justify banishing me to the "other theories" forum?

No, by all means post one. But calling it the 'correct' one implies that Einstein's equation is the incorrect gravitational time dilation equation when in fact that equation has nothing to do with gravity at all. That equation was not described until a later paper.

I'll try to point out some issues in this post. These have all been identified before.

There seem to be three different scenarios and you seem to want to apply the same equations to any of the three at times. This in itself is serious mistake. The 3 are:
Case B: Ships (clocks, observers, whatever) all having the same proper acceleration, starting simultaneously from a stop relative to some inertial frame in which both are initially stationary. I call this case B because it is exactly Bell's spaceship scenario. https://en.wikipedia.org/wiki/Bell%27s_spaceship_paradox
Case R: Rigid motion where there is one long spaceship with a clock/observer/whatever at either end. The proper acceleration measured at either end does not match the other.
Case T: The twins scenario, with only one guy accelerating and the other just sitting waiting for the reunion.

Einstein said that a clock (and co-located "helper friend (HF)")

Again, what possible purpose is served by this HF? If he reads the clock, what good is that? Is his job to assert things? I digress. The HF is not what's wrong with all this, it just seems entirely superfluous.

Einstein said that a clock whose acceleration "A" is the same as the designated observer's (the "DO's") acceleration

Just pointing out that they both have identical proper acceleration, making this case B. I've pointed this out before, but you often try to make it into one of the other cases.

with both of them beginning the acceleration at the same instant with synchronized clocks (and ages) at that instant), and leading (in the direction of the acceleration) the DO by the constant distance "L", will tic faster than the DO's clock, by the ratio exp(L*A).

Here is a great example of your biggest consistent mistake: Lack of frame references. You (and Einsten) say that they begin the acceleration simultaneously, but due to RoS, that is meaningless without a frame reference. So to be clear, they start simultaneously in frame F, the one inertial frame in which they both were initially at rest.
Since both clocks have identical acceleration profiles in frame F, they remain in sync in F, that is to say that at any moment, both clocks simultaneously read the same value. You say that the lead one ticks faster, but it doesn't in frame F. So you perhaps mean a different frame, but you don't specify it. Other suggestions might be the accelerated frame of DO or perhaps he accelerated frame of HF. You don't say, but you do say "leading the DO by the constant distance L" which is not true in any frame where HF ticks faster than DO.
See what I mean? You're mixing different frames in a single assertion. That whole description is an unworkable mess. Give the frame specifications so I can show which assertions are appropriate and which are wrong. There's no frame in which all of that can be correct.

Your reaction to such feedback is usually to dismiss the critique because you know it's just not possible that you've made a mistake. If so, yes, your posts very much belong in the lighter-side where we put stuff that's wrong.

The "designated observer" (DO) is the person whose conclusion we want to know, about the current reading on each of the clocks in the array.

Fine, but one has to specify which coordinate system is being used by DO. Is it F? Is it his own Rindler coordinates? Lass coordianates? Do you know which of these Einstein is using? He at least specifies his frames.

Einstein clearly regarded the quantity "L" as being constant during the acceleration

Does he say that? If so, does he say in which coordinates this is true, because it's true only in one of them. Making strawman claims of what he's asserting is another mistake.

Einstein's exponential equation tells the DO, at each instant of his life (after the constant acceleration "A" begins), what the reading on each of the clocks in the array is

This again utilizes simultaneity without specification of coordinate system. Your statement is not even wrong until you do this. An instant at DO is not that same instant at some other location without the frame specification.

I eventually was able to derive the correct gravitational time dilation equation, and it can be used to construct the accelerating array of clocks and HF's that correctly establishes the "NOW at a distance" for the DO, and that makes the DO's conclusions meaningful to him.

Here you're equating acceleration to gravity. That works only locally, but you're trying to apply it non-locally. There is no gravity in the accelerating case.

I think what might be confusing you (Halc) is that you are probably looking at the scenario through the eyes of a perpetually-inertial observer. (I.e., you are interested in the conclusions of perpetually-inertial people, about what is happening to the separation between the accelerating clocks.)  In my analysis, I don't consider the conclusions of any perpetually-inertial observers at all, and don't need or want to.

I'm not interested in any observers at all since they only can observe what's in their immediate presence. But the frame specifications are crucial, and they're missing in your 'proof', rendering it meaningless. Try to actually entertain the idea that I have a point here.

The acceleration "A" that each clock and their attendants (the DO and the HF's) are undergoing is produced by a rocket attached to each of them, and controlled by an attached accelerometer that always insists on a measured acceleration of exactly "A".

Ah good, that's the first in this post where you clearly specified constant proper acceleration. You're definitely case B then.

The post to which you said I was wrong was this comment of mine in another thread:
"It is impossible to keep an array of clocks mutually stationary wrt some accelerating reference worldline. Some of them can be kept stationary if the acceleration schedule is known, but not all of them."
That comment was about a case R (rigid motion) situation where the proper distance between the accelerating clocks is constant, and thus the proper acceleration of those clocks is not constant.

15

Physics, Astronomy & Cosmology / Re: Why can't i understand the andromeda paradox?

« on: 15/02/2023 18:39:44 »

Could you elaborate on why it is impossible to keep all the clocks in the array stationary for an accelerating observer, even with knowledge of the acceleration schedule?

Given a pattern of acceleration (especially one that isn't constant), the lines of simultaneity at time 0 and at time 1 will not be parallel, and thus will cross at some location in space. Anything beyond that point (the Rindler horizon  https://en.wikipedia.org/wiki/Rindler_coordinates) would require the object to be at different locations at a given time or to have to move at greater than light speed to remain at the same location relative to the reference thing accelerating.
So for instance, one observer might accelerate at 1g for 10 seconds and then 'coast'. The lines of simultaneity in the inertial frames before and after the acceleration cross about a light year away in the direction away from the acceleration vector. This means that if I have a light-year long pre-stressed rocket, no amount of thrust applied at the rear can cause the front of the rocket to accelerate at 1g or more.  I say pre-stressed so one doesn't have to wait a year for the thrust at the rear to be felt at the front. A building for instance is pre-stressed since it isn't built in free fall and then suddenly placed on the ground.

16

Plant Sciences, Zoology & Evolution / Re: The Speed of Life

« on: 11/02/2023 16:28:17 »

My question is, the timescale of living things, we have the Mayfly — The Shortest Lifespan

Mayflies live about a year. It's just that they don't last too long after puberty, not even retaining the means to eat.

As for long-lived things, every amoeba is arguably tens of millions of years old. They're not born, so its hard to define when they 'started'. Just saying, not everything goes through the steps of birth, growth, repro, and death.

Many creatures have aging and death built into their genetic makeup, including us. It was an evolutionary adaptation that made the species more fit.

Or is life just based in human time life spans?

Don't know what you mean by this. Is it measured in terms of human life spans? No, it's usually measured (by us) in hours, day, years, or more standard (to us) units of time like that. I don't think you're asking that, but I cannot figure out what you actually are asking.

17

Physics, Astronomy & Cosmology / Re: Will tidal power cause the moon to crash into us?

« on: 09/02/2023 02:32:58 »

You do now have me wondering if it is possible (barring the Sun's future death, as we are talking about very large time scales here) for the Earth-Moon system to evolve in such a way that the Moon ends up at the L₁ Lagrange point. That way, the Sun, Moon and Earth could all be tidally locked to each other.

Barring the Sun's imminent death indeed, so we'll ignore that.

The future is a tidal lock occurs around a 1440 hour day/month, which is about two current months. At that point the angular momentum of the system is what it is now, but with everything spinning at the same rate, so no more energy to push it further.
At that point the sun becomes the primary drag and the energy/momentum slowly drains away. The days begin to get shorter again and the moon starts dropping in orbit, all while the two stay tide locked. Eventually the day gets back down to around 12 hours (it used to be less than that in the past) and the moon crosses the Roche limit and Earth gets some spectacular rings like Saturn. Most of that will fall to Earth eventually, but in pieces, not one big chunk.

Mars is on the verge of doing this right now with Phobos to cross the Roche limit in perhaps 70 million years, but it's so small the rings resulting won't be that dramatic. It's also different with Mars since it is not tide locked with either moon, which heavily contributes to the rate at which its orbit declines.

18

New Theories / Re: What is the real readshift in the Cosmic Microwave Background (CMB)

« on: 08/02/2023 13:10:02 »

My simplistic understanding of what they said is:
- Roughly 15 (or 14) billion light years is the distance from "where the source was when the light was emitted" to "where we are now"

It's actually about 1/10000th of that. In cosmic coordinates (the only coordinate system I know that describes the universe), the oldest light we see (that of the CMB) was emitted at a proper distance of about 1.5 million LY away. The reason it took 13.8 billion years to get here is due to the very high expansion rate of the universe back at the time of the recombination event, perhaps 3M km/sec/mpc compared to 70 km/sec/mpc today.

Roughly 100 billion light years is the distance from "where the source is now" to "where we are now"

That would put it beyond the size of the visible universe which means we could not see it. So around 45 billion light years is the proper distance from "where the source is now" to "where we are now".

- There is an even smaller number which represents the distance from "where the source was when the light was emitted" to "where we were back then"

Well since we have not moved significantly in that time, that distance is also that 1.5 MLY figure. Cosmic coordinates has the Earth at the center, unmoving. You have to assign the origin somewhere.

As relativity illustrated, all times and distances are relative to which frame of reference you are talking about

Yes, which is why I carefully specified the cosmic frame and not say some inertial frame, which isn't valid at all at large distances since spacetime isn't Minkowskian.

And anything outside your light cone is irrelevant to you (eg if some object is now 100 billion light-years away, light from that object will probably never reach us, due to the expansion of the universe).

Correct. Any recombination light emitted from what is currently over about 58 BLY away will never reach us. Any light emitted today from over 16 BLY away will also never reach us. That latter figure is the current distance to the event horizon.

19

Physics, Astronomy & Cosmology / Re: As The Andromeda galaxy gets Closer Do We See It Younger ?

« on: 03/02/2023 21:32:00 »

Because we are not moving towards each other at the speed of light will it not appear younger as it gets closer because the light from it is travelling a lot faster than it is travelling towards us ?

Actually, I fixed my first post. The faster something comes at you, the faster it appears to age. Andromeda appears to age an extra hour every 3 months of us watching it. If something approaches us near speed of light, it can appear to age twice as fast, or a thousand or more times. This is mostly due to Doppler effect. Things moving away appear to age more slowly, so those really distant galaxies are very young looking because their appearance has had no time to age them beyond their lambdom.

Spell checker didn't like that word. Not sure why not.

20

Physics, Astronomy & Cosmology / Re: As The Andromeda galaxy gets Closer Do We See It Younger ?

« on: 03/02/2023 15:27:17 »

So, as Andromeda gets closer will we be bale to see it get younger as the light won't need to travel so far is not it ?

No. It will always appear to be aging forward (faster than us even), so in a year it might appear a year plus 4 hours older..