1

New Theories / Re: What is non-returning twin paradox?

« on: 28/09/2023 13:41:25 »

This is also incorrect since the conclusion is abstract (mental, not physical) unless they are in each other's presence, in which case it is called 'differential aging', which is the unequal comparison of clocks physically in each other's presence.

Do you mean that A's clock will be equal to B's clock at the destination point?

No. 8y is not equal to 9y 2m.  Why would you suggest otherwise?

So, you are not confused if the problem can be simplified to 0 or 1 inertial frame change, but you start to get confused with 2 or more inertial frame changes. Cmiiw.

As I said before, doing it via frame changes just adds complications, requiring multiple formulas, some of those being more complicated.

Using what I showed, no frame change is made ever. You pick just one and stick with it.

The confusion comes from asymmetrical results produced by symmetrical situations.

The situation was never symmentrical, and if it is (like the one in one of your recent threads), then the result is very much symmetrical. But adding more characters just adds more complications which is inadvisable if you cannot in any way understand even the simplest case.

How much difference is caused by the changing reference frames?

None actually, since a change of reference frame is a mental abstraction, not physical. A mental change doesn't in any way alter what actually happens.

The other half is asymmetrical results between the twins, which means that one of them will observe time contraction of the other twin, instead of time dilation.

There is no such thing as 'time contraction'. There is time dilation, but you speak of this time contraction as if it is something different.

t's the cause of this supposed asymmetry which created disagreement among physicists.

You're making up facts. There's no conflict when different physicists explain it in different ways since none of the explanations are wrong. But the way I showed seems the most simple, and requires but the one equation.

Halc's answers. Reply #1 only addressed half of the question, which is reasonably hasn't touched the paradoxical part.
Perhaps the misunderstanding can be avoided if we use the term "switch of inertial frame" instead of "change of inertial frame"

I didn't touch on a paradoxical part because there isn't one.
The misunderstanding can be best avoided if we avoid switching inertial frames altogether, as I suggested in post 1.It only leads to confusion if you don't understand how to do it right, and doing it right that way is considerably more complicated than sticking to one frame as I suggested.

Lorentz factor is usually represented by gamma symbol γ instead of lambda λ.

I stand corrected on that one

Reply#15 is supposed to answer time dilation experienced by twin A as observed/calculated by twin B. But he refused to give numeric result, on the account that twin B switched his frame of reference.

I instead encouraged you to work it out yourself. Even an attempt with mistakes would have been a learning experience, and we could have helped. But you declined since apparently learning anything isn't your goal. Hence my not bothering to reply much anymore.

The answer is easy. If 'the frame of B' is used, 8 years are logged by twin A, and 9y2m by twin B.

The video below tries to solve twin paradox using acceleration.
But this video below doesn't touch the paradox yet. It only describe time dilation observed by earth twin, without being bothered by travelling twin's perspective.

The first is a terrible video. It has many errors, such as asserting that they see each other age more slowly, which is only true when they watch each other recede. The twins scenario is not in any way about what anybody sees. Then they try to explain things via gravity which is utterly wrong. This is a special relativity scenario in which gravity is never taken into consideration.

The second video isn't much better. It say 'time slows down as you approach the speed of light'. That's just wrong. 'I move at nearly light speed relative to a muon created in the upper atmosphere. It doesn't make time slow down to me. He then attempts to reference an invalid frame of a light-like worldline, which is obfuscation at best, and wrong at worst. He never actually gets back to the twins after that.

There are good videos out there, but hunting down bad ones seems a favored pasttime to those that don't want to learn. Take the advice of other posters and find a good physics text if you actually want to learn this, which I suspect you don't. Stay away from you-tube, pop sites, and especially social media.

Let's describe the same case from twin A's perspective. He stays in his own reference frame, while Alpha Centauri moves closer at 0.4c.

This statement is incorrect.  Twin A does not stay in his own constant inertial frame.  He starts in earths frame, accelerates to the cruising frame then decelerates to Alpha Centauri's frame.

His statement is pretty much my words from post 9. The statement doesn't suggest that any planet undergoes any acceleration. I was talking about the frame in which A is stationary for the entire duration of the exercise. Everybody 'stays in' this frame since it is impossible to exit an inertial frame. To 'be in' a frame is simply to have valid and unique coordinates to your event in that frame. So acceleration doesn't necessarily cause a change of frame, since a frame is simply an abstract choice, and the simplest choice is to never switch frames. So the other players (planets, twin B) are still in this frame, they're just not stationary relative to it.

Relative to that frame, which we've called 'A's frame', Alpha Centauri moves closer to twin A at 0.4c. There's no suggestion that it needed to accelerate to do so since it was always moving at that speed relative to that frame, as was Earth. Yes, twin A needed to accelerate to a halt in that frame, but that fact is irrelevant since he spent zero duration at that alternate speed. Acceleration computations do not figure into the simplified method I suggested in at the top.

2

New Theories / Re: Universal Utopia? What's The Universal Terminal Goal?

« on: 26/09/2023 01:11:32 »

In this video, a Universal Basic Services is proposed, instead of Universal Basic Income.

Electricity is one of the most common basic utilities in modern society.

Thanks for the video. I wish there were more places like this.

Peer reviewed research has passed scrutiny by competent fellow researchers while a video can say anything, regardless of truth.

Agree. Especially now, when misinformation is spreading at incredible speed, and the text on many sites is generated from pieces of text by incompetent translators, it is essential to trust trusted sources. I encountered this when I wrote a Holocaust paper in college. I came across dozens of resources where information was presented, as the site owner liked it. However, I could still find a reliable source like https://edubirdie.com/examples/holocaust/ where professionals wrote the text based on verified facts. It is important to check the information you use, so between a peer reviewed publication and a YouTube video, I will definitely choose the first one.

3

New Theories / Re: What is non-returning twin paradox?

« on: 17/09/2023 16:14:56 »

This is a slightly modified twin paradox to distinguish the effects of relative speeds and acceleration.

In a different inertial reference frame (one in which both stars are moving at -0.4c), this is pretty much exactly the twin paradox, with twin A being stationary the entire time, and twin B going out and back, albeit at 0.4c only outbound, and faster on the return.

OK, so this is trivially computed in the Earth frame. The resolution for any exercise in special relativity is to simply choose a frame (we'll pick Earth since Earth time was specified), all you need to do is compute the dilation factor due to the speed relative to that frame. This is computed (in natural units) with

λ = 1/√(1-v²)

Twin A started a journey to Alpha Centauri 4 light years away in a space ship moving at 0.4c  is expected to arrive 10 years later, according to earth observer.

OK, so in Earth frame, λ=1.091 so 10 / 1.091 = 9 years 2 months elapsed time for twin A.

Twin B stayed home to improve the space ship, so he can go to Alpha Centauri 5 years later at 0.8 c.

0.8c yields a λ of 1.667 so 5 years at home and 3 during the trip, so 8 total.  Not so hard, right? You can do this yourself without asking each and every time.

Classical physics calculation predicts that they'll arrive at Alpha Centauri simultaneously.

Classical in what sense?  Classical physics refers to non-quantum physics. I think you mean Newtonian physics, not classical.  Yes, every theory (including Newtonian) says they get there simultaneously. This is an objective fact, true in any reference frame.

How old are they when they meet up at Alpha Centauri?

As computed above, 9y2m and 8y respectively.

4

General Science / Re: How does ChatGPT work?

« on: 13/09/2023 14:08:00 »

Here's a first hand information intended for general audience.

The Inside Story of ChatGPT’s Astonishing Potential | Greg Brockman | TED

In a talk from the cutting edge of technology, OpenAI cofounder Greg Brockman explores the underlying design principles of ChatGPT and demos some mind-blowing, unreleased plug-ins for the chatbot that sent shockwaves across the world. After the talk, head of TED Chris Anderson joins Brockman to dig into the timeline of ChatGPT's development and get Brockman's take on the risks, raised by many in the tech industry and beyond, of releasing such a powerful tool into the world.

Thank you... That's very Interesting and quite exciting really. My friend was just telling me about this and I find it fascinating!

5

Physics, Astronomy & Cosmology / Re: What is the exact cause of the time dilation of the twin?

« on: 05/09/2023 18:32:23 »

Let's start with the simplest frame of reference first, which is the midway observer. What will he observe when he meet both travelling twins? At that moment, what's shown by his own clock, and the clocks brought by the travelling twins?

Assuming the mid way point is exactly 2 ly and the twins acceleration was instantaneous:
Twins speed 0.999c.  From the frame of the observer at the mid point the elapsed time on the clocks would be:
1.  Mid point clock - 2.002 years
2.  Earth twins clock - 0.0894 yrs
3.  Alpha Centauri twin - 0.0894 yrs

6

Physics, Astronomy & Cosmology / Re: What is the exact cause of the time dilation of the twin?

« on: 21/08/2023 17:48:17 »

It's seems to me that you are trying as hard as possible to Not understand Relativity.

It seems like that to you because you've been misunderstanding it without you realized.

What's the reading of the travelling clock by midway observer, one day before passing the mid point, and one day after passing it?

Outbound trip:
0ne day prior to ship arriving( by Midpoint's clock):

Actual time on ship clock: 32 days, 15 hrs, 34 min and 13.5718217858 sec.

What the Midpoint observer visually sees: The ship sitting at its planet of origin, waiting to depart.

One day after ship passes midpoint:

Actual time on ship:  32 days, 17 hrs, 42 min, and 59.490547741 sec

What the observer visually sees: 32 days, 17 hrs, 10 min, 48.9770892 sec

During return leg:


One day before: 
Actual time: 98 days 0 hr, 51 min, 26.63419131 sec

What is visually seen: The ship not quite having reached the turn around point, and a bit short of reading 65 days 9hr, 17 min, and 13.06236952 sec
One day after:
Actual time: 98 days 3 hrs, 0 min, 12.55291726 sec

What is visually seen: 98 days 2 hr, 28 min, and 12.5529176 sec.

7

Physics, Astronomy & Cosmology / Re: What is the exact cause of the time dilation of the twin?

« on: 18/08/2023 16:53:15 »

To be consistent, let's use the speed used in Don Lincoln's video, which is 0.999c.
Here are the observations of those 5 key events as recorded by midway observer.
1. The journey starts on earth at t=0 local time. The light signal takes 2 years to the midway observer, thus he will see the event when his clock shows t=2 years. Journey from Alpha Centauri is the same due to symmetry.
2. The travelling twins take 2 ly / 0.999c = 2.002... year to get to the midway. Thus the observer will see his clock showing t=2.002... years.

During which time the midpoint observer will see the traveling twins' clock Doppler shifted by a factor of 44.710, and accumulating 44.710 * .002 = 0.089 yr, thus having their clocks each reading 0.089 yr upon reaching the midpoint.

3. The journeys take 4 ly / 0.999c = 4.004... year to get to the turning point in on going leg. But it takes additional 2 years for light signal to the midway observer, thus he will see the event when his clock shows t=6.004... years.

After each twin passes the midpoint, and are receding from it, the Midpoint observer will seeing them Doppler shifted by a factor of 0.0224, with each accumulating 4.004 * .0224 = 0.89 yr on their clocks to read 0.178 yr upon arrival at their destinations. (while the clocks at the destinations will read 6.004-2= 4,004 yrs)

4. The travelling twins take 6 ly / 0.999c = 6.006... years to get to the midway in return leg. Thus the observer will see his clock showing t=6.006... years.
5. The total journeys take 8 ly / 0.999c = 8.008... years to get home in return leg. But it takes additional 2 years for light signal to the midway observer, thus he will see the event when his clock shows t=10.008... years.

The return legs are just mirrored versions of the outbound legs, and give the same results, with an additional 1.79 yrs added to each twin's clock and 4.004 yrs added to the planets' clocks as seen by the midpoint observer.

8

Just Chat! / Re: What's your advice on writing a series of story?

« on: 09/08/2023 17:37:36 »

What I meant was to amplify those above average abilities to extraordinary levels as far as permitted by natural laws, like conservation of momentum and thermodynamics.

I'm rather fond of exploring ideas like that myself. I often find it hard not to think deeply about the nature and consequences of superpowers. When trying to come up with my own fictional world, I tried calculating an upper limit on they might be capable of achieving. My idea was that their bodies convert nitrogen in the air that they breathed into energy ala E=mc² (since the body doesn't need the nitrogen we breathe anyway). I still have the resulting power written down in a notebook somewhere. It was a lot, obviously. Didn't have an obvious solution for how they would convert it all into useful work without cooking themselves, though.

9

Just Chat! / Re: What's your advice on writing a series of story?

« on: 07/08/2023 18:55:45 »

Outline your saga, pick out the best story and publish that first, then release prequel and sequel stories, sell it to Disney and retire.

10

Science Experiments / Re: Investigation on diffraction of light

« on: 06/08/2023 21:18:10 »

I've been avoiding to post Utube vids...anywayz, here it is...

Thanks & Credits & Source -
Mithuna Yoganathan/Looking Glass Universe(channel)/YouTube.

11

New Theories / Re: How close are we from building a virtual universe?

« on: 21/07/2023 17:23:33 »

Forgery is forgery, and we've had to live with it for as long as anyone has valued authenticity.

Yes.
But my chequebook was only at risk from a skilled forger.
That wasn't a big threat to me.
But now any Tom Dick or Harry can make a practically perfect facsimile of my signature/ face/ social media account/ whatever.
So, yes, forgery was always a problem.
But it suddenly got much worse.

12

New Theories / Re: Universal Utopia? What's The Universal Terminal Goal?

« on: 21/07/2023 13:52:41 »

What's the biggest benefit of this concept?
What are the problems it's trying to solve?
What are the fundamental assumptions?

Don't be silly - it's philosophy, not engineering!

13

General Science / Re: How does ChatGPT work?

« on: 03/07/2023 20:47:02 »

A tad bit Worrying...

Nobody knows how it Works.
Opens up the possibility of it Miscalculating.

If 99 times out of 100, it says 2+2=4, & gets it wrong once, is Totally Fine.

Can only Hope autonomous ai systems won't be deployed for Nukes.

99.999% accuracy with an Error margin of just 00.001% will be
Game Over!

Humans have even higher error rates. Nonetheless, we survive, so far. Even with nukes available for decades.
What's needed is some reliable system for check and balance, and acceptable common goals.

https://en.m.wikipedia.org/wiki/Stanislav_Petrov

14

Just Chat! / Re: Is there a universal moral standard?

« on: 26/06/2023 16:03:55 »

This side of the pond things are a bit different despite being historically based on English law. My "boss" is a registered psychiatric nurse and she never gets called for jury service while I have been called several times.

15

Science Experiments / Re: Double | slit | Experiment?

« on: 18/06/2023 20:22:57 »

Yup!
It indeed is BS.
Propagated by certain Utubers as clickbaits to get more n more views.

The tree falling would create a shockwave.
The surrounding ground could be tested for clues.

The moon at times isn't visible, but tides exist.
Also moon formed before, abiogenesis later.

It is just a Probability of the cat being dead or alive, the final possibility ain't dual in nature.

I'm Sure you All have seen stuff online sayin " Physicists prove Reality is not Real " & " Scientists confirm the Universe doesn't Exist ".

Lay folks like me read up all this Stuff n feel soo cool & good.
Until we bump into a REAL scientist...
It doesn't end well for us.
: (

Philosophy, Religion, Politics are Plagued sure enough.
But Science has a few bad rats too!
(sorry)

16

New Theories / Re: Where does quantization of energy of electromagnetic radiation come from?

« on: 15/06/2023 08:45:56 »

This tells you about flame absorption spectra.
https://www.agilent.com/en/support/atomic-spectroscopy/atomic-absorption/flame-atomic-absorption-instruments/how-does-aas-work-aas-faqs

The sample shown in the article is Pb. Turning it into gas requires high temperature. If the element is already gaseous in room temperature, like hydrogen, the flame doesn't seem to be necessary.
The flame is not shown in the pictures I posted either.

Heating has three effects.
One is converting the material to vapour- which is not important for hydrogen.
Another is converting the material into atoms (rather than molecules).
That's important for hydrogen, but not with (for example) mercury.

And the third thing heating it does is raise some of the atoms to their first excited state.
The ground state of hydrogen atoms doesn't absorb visible light.

17

Science Experiments / Re: How do electromagnetic couplings work?

« on: 13/06/2023 23:25:00 »

Great stuff!

Many thanks for the magnetic amplifier video - it took me back nearly 60 years to using Acromag magamps to detect very small currents in a linear accelerator. As the man said, we had no high-voltage transistors and vacuum tubes produced a lot of heat and were a bit fragileso magamps were favored for guided missile control systems as they are utterly robust and useful servo drivers, but I was interested in their very low inherent noise. Must have a couple in the workshop drawer somewhere!

18

New Theories / Re: Where does quantization of energy of electromagnetic radiation come from?

« on: 13/06/2023 17:33:05 »

Hi.

About the videos:
   I've only glanced at some bits of the videos you (Hamdani) presented.   They seem to support the idea that Planck focused on the oscillators in the walls.  See, for example,  around 6:10 ~ 6:30 in the first video where the narrator states that light came from those quantised oscillators. 

   I found at least one statement that was made which isn't necessarily true.   In the second video at about 7:00 to 7:30  the narrator discusses the use of a cuboidal shaped cavity for the mathematical model (which is the typical choice).   There is a fairly casual statement made that any shaped cavity could have been used, the result would be the same but the maths would just be harder.   That is not at all obvious and I don't think it should be stated as established fact.  There are several adjustments to the method that would normally be made.  In particular, there are some extra assumptions that seem essential and must be added to the mathematical model to correctly predict that very small and peculiarly shaped cavities will still ultimately produce the usual BB spectrum.
   There are some pieces of equipment which work purely because there is a cavity (including a suitable material for the walls of the cavity) with the right shape and dimensions to seriously influence the spectrum or frequency of radiation that is supported.   (See, for example, the discussion of lasers, resonance and cavities  in this post  https://www.thenakedscientists.com/forum/index.php?topic=86164.msg700593#msg700593   which you (Hamdani) seemed to approve of at the time).   
 
   The videos do seem to take a fairly conventional approach and walk you through how you must have stationary e-m waves that fit inside the cavity,   only these will be considered as supported "modes" of radiation.    Overall, the mathematical model discussed (which is a typical derivation for the BB spectrum) is just an approximation but the narrator doesn't make it apparent where all of those approximations are made.   For example, at time 8:05 to 8:30 in the second video a formula for the density of modes is said to be "not easy to find" and just written down.   This is important because it's only this approximation which allows us to finish with a continuous spectrum rather than just a discrete set of frequencies.    So, it's important to note that the entire method, even for simple cuboidal shaped cavities, is just an approximation.   As suggested earlier, you need some additional approximations or assumptions before you could be certain that an arbitrary shaped cavity would still give rise to the usual BB spectrum.

[LATE EDITING:  This post is already long, I've removed further discussion about the mathematical model(s) used for deriving the BB spectrum in very small and peculiarly shaped cavities.   There's no need to side-track the thread too much].

Best Wishes.

19

New Theories / Re: Where does quantization of energy of electromagnetic radiation come from?

« on: 12/06/2023 22:57:59 »

Why does a hydrogen atom have quantised energy?

It's all down to Heisenberg and Schrodinger.

No.
Grass was green before either of them was born.

20

New Theories / Re: Where does quantization of energy of electromagnetic radiation come from?

« on: 05/06/2023 17:01:50 »

Hi.

Can it describe interaction between two permanent magnets?
How about a magnet and a small ferromagnetic material?

   In general Maxwell's equations are used for Magnetostatics.  As @paul cotter  stated,  some are more relevant than others and the Biot-Savart law is useful.    You can get the Biot-Svart law out of Maxwell's equations with minimal assumptions.

    They won't model the force between permanent magnets and ferromagnetic materials on their own.   You need to make a few additions:
   (i)  Assign a magnetic substance a (vector) Magnetisation  M.   This depends on the properties of the material.   LaTex still isn't working so you can't have any formulas, only words.     It is the vector sum of magnetic dipole moments per unit volume of the material.
    (ii)  You also have to understand what a magnetic dipole is.   In general they can always be modelled as being equivalent to a microscopic loop of current.   (We have terminology like "bound current" to describe the equivalent current that would create the dipole that exists in a place.   Sometimes that can be thought of or identified as an actual current, e.g. an electron whizzing around an atom.  Sometimes it can't.  Bound current is not usually an actual current but just a way of modelling a magnetic dipole).
    (iii)   Make assumptions about how magnets and magnetic materials behave.   The microscopic explanation doesn't necessarily need to concern us (but there is one, with varying degrees of sophistication and accuracy).   For the macroscopic behaviour you only need to know how the Magnetisation,  M,  of a magnetisable material will vary with an applied field.    So, for linear materials we have   M  =  χ_m H   with  χ_m = a constant called the magnetic susceptibility.    The H field for a simple linear material is just a linear multiple of the B field,   B = μH  with μ being the permeability of the material (rather than μ₀ as for a vacuum).

   I think that's enough additions.   With that you will be able to determine the forces between magnets and/or simple linear magnetic materials.   Basically all magnets are just a collection of magnetic dipoles and magnetic materials become a collection of dipoles in their Prescence.   So the final determination is entirely based on the fields and forces exerted on and by magnetic dipoles.

    I think there was a previous post or two that discussed non-linear materials.  That's more complicated.

   As outlined by @alancalverd ,  dipoles don't follow an inverse square law for the field strength they produce.   At large enough distances, it's an inverse cube law.   (To be honest I'm surprised Alancalverd uses a 1/r² law as an approximation at any range - but very close it isn't a perfect 1/r³ law,  which we both agree on)
   To further complicate it, in addition to the thing that created the field being a dipole, the thing that is acted on by the field is also a dipole.   So it experiences a force that depends on the gradient of the B field instead of being directly proportional to B (we have F = Bm for a simple monopole of magnetic charge m    but  F = ∇(B.m) for a dipole moment m).   
    So at large distances a dipole experiences a force from another dipole that falls off ~  1/r⁴.  This assumes that both dipoles were permanent and unchanging dipoles.   If only one had been a permanent magnet and the other is merely a magnetisable material, then  (by the relationship M = χ_mH )  the magnetisable material becomes less magnetised the further away it gets from the permanent magnet.  So the force existing between the permanent dipole and the magnetisable material falls off with an even higher power (~ 1/r⁷ ).

I know formulas are not always displaying well.  See  https://en.wikipedia.org/wiki/Force_between_magnets#Magnetic_dipole%E2%80%93dipole_interaction
for some discussion of constructing  the 1/r⁴  formula for the force between two magnetic dipoles. 

Best Wishes.