[hamdani yusuf (OP)]

Time dilation is not a function of acceleration and there's no mathematical formula expressing it in terms of acceleration.

If acceleration has no effect on time dilation, then the observation of the accelerated twin should be equally valid as non-accelerated one.
Alternatively, there must be something else which makes their situations different, such as their relative motion against an external object, like CMB.

[hamdani yusuf (OP)]

Any thoughts about this?

Here's another video responding to those in the op.

The REAL Reason You Don't Understand Relativity

Think Relativity is confusing? Well, it's not just you -- even the experts can't seem to agree on its meaning, and often get basic facts about the formalism completely wrong. Here, we critique one such renowned professional who, in claiming to be clarifying the standardized theory of relativity, turns out to actually be promoting a misguided personal interpretation. What is this expert's confusion exactly, and why are such misconceptions so prevalent amongst the physics community?

Indeed, be cautious of posturers, gaslighters, stigmatizers, and Giordano-Bruno-burners who want to convince you that your inability to understand Relativity stems from your own deficient reasoning -- because when even the experts can't agree, you know there is something up...

Contents:
00:00 - Intro
01:11 - The Many Interpretations of Relativity
04:55 - Examining Sabine's Interpretation, Pt. 1
08:30 - Examining Sabine's Interpretation, Pt. 2
10:58 - The Source of Confusion
12:12 - Are There Better Interpretations?

[Janus]

Time dilation is not a function of acceleration and there's no mathematical formula expressing it in terms of acceleration.

If acceleration has no effect on time dilation, then the observation of the accelerated twin should be equally valid as non-accelerated one.
Alternatively, there must be something else which makes their situations different, such as their relative motion against an external object, like CMB.

The observation of the accelerated twin is equally valid.   It is just that his observations are effected by his acceleration while he is actively accelerating. This includes clocks in the direction of the acceleration running fast compared to his own by a factor determined by the magnitude of the acceleration and the distance to the clock.
An analogy would something along these lines:
Two men are back to back and then separate. According to each of them, the other is a given distance "behind" him. Man 1 them turns 180 degrees.  By his perspective, Man 2 goes from being behind him to being in front of him.  As far as Man 2 is concerned Man 1 is still behind him, and this did not change when Man 1 turned around.  The observations of each is equally valid.
With Relativity, time is also involved, And "front" and "back" are replaced with temporal measurements. Acceleration involves a reorientation in space-time for the accelerated observer. 

[hamdani yusuf (OP)]

Here is a link that Fermilab put out,

.  At 12:00, it explains that the reason for the time dilation of the twin is because of the change in direction and not acceleration (although he does say that acceleration plays a small part).

Imagine we can put 5 giant clocks synchronized to each other, after being placed close to the trajectory of the space ship. They are all stationary in earth frame. First clock is on earth, second clock is 1 light years away, and so on, and the fifth clock is near the destination star.
At the beginning of the journey, earth observers see the fifth clock using a powerful telescope, and see year 0. At the same time, fourth clock shows year 1, third clock shows year 2, second clock shows year 3, first clock on earth shows year 4.
What will the travelling twin see when he is passing those clocks?

[Origin]

What will the travelling twin see when he is passing those clocks?

I suppose it would depend how fast he was going.

[hamdani yusuf (OP)]

What will the travelling twin see when he is passing those clocks?

I suppose it would depend how fast he was going.

The video at 2:45 timestamp says 99.9% of light speed.

[Origin]

At the beginning of the journey, earth observers see the fifth clock using a powerful telescope, and see year 0. At the same time, fourth clock shows year 1, third clock shows year 2, second clock shows year 3, first clock on earth shows year 4.
What will the travelling twin see when he is passing those clocks?

So at 0.999c we can approximate the speed at c.  The first clock of course would read 4, the next would read 5, the next would read 6, the next would read 7 and the last would read 8.

[hamdani yusuf (OP)]

So at 0.999c we can approximate the speed at c.  The first clock of course would read 4, the next would read 5, the next would read 6, the next would read 7 and the last would read 8.

Continuing your reasoning, on the return trip, he will read 9, 10, 11, and finally 12 when he gets back to earth.
Is it really this simple? Do you think the paradox is solved this way?
If the travelling twin brings a smaller clock which is synchronized to the earth clock at the beginning of the trip, what does it read when he's passing the giant clocks?

[Origin]

Continuing your reasoning, on the return trip, he will read 9, 10, 11, and finally 12 when he gets back to earth.

Let's not jump forward until you respond to my assessment of the scenario you presented. 
It is my contention that if there is a clock 1 ly away from the earth and a ship moves at ~c from the earth to the clock then the clock will show that 1 year has elapsed.  Do you disagree?

[hamdani yusuf (OP)]

I asked Google Bard, what's the best explanation to the twin paradox?

The twin paradox is a thought experiment in special relativity involving identical twins, one of whom makes a journey into space in a high-speed rocket and returns home to find that the twin who remained on Earth has aged more.

The paradox arises because, according to special relativity, moving clocks run slower than stationary clocks. So, if the traveling twin is moving at a high speed relative to the Earth-bound twin, then their clock should run slower. However, the traveling twin could also argue that they are stationary and the Earth-bound twin is moving, in which case the Earth-bound twin's clock should run slower.

The resolution to the paradox is that the twins' situations are not symmetrical. The traveling twin undergoes acceleration during the journey, while the Earth-bound twin does not. Acceleration breaks the symmetry of the situation and allows for a difference in aging between the two twins.

The amount of time dilation that occurs depends on the speed and duration of the journey. For example, if the traveling twin travels at 99% the speed of light for 10 years, they will return to Earth 20 years younger than the Earth-bound twin.

The twin paradox is a fascinating example of the strange effects of special relativity. It highlights the importance of acceleration in determining how time passes.

Here are some additional details about the twin paradox:

The paradox was first proposed by Hermann Minkowski in 1909.
The first experimental test of the twin paradox was conducted in 1971 by the Gravity Probe A team.
The twin paradox has been used to explain a number of other phenomena, such as the aging of astronauts in space.
The twin paradox is a reminder that our intuition about time is not always correct.

[hamdani yusuf (OP)]

Continuing your reasoning, on the return trip, he will read 9, 10, 11, and finally 12 when he gets back to earth.

Let's not jump forward until you respond to my assessment of the scenario you presented. 
It is my contention that if there is a clock 1 ly away from the earth and a ship moves at ~c from the earth to the clock then the clock will show that 1 year has elapsed.  Do you disagree?

Agree, the clock should read 1/0.999 ≈ 1,001 year when he is passing the second clock.

[Origin]

Agree, the clock should read 1/0.999 ≈ 1,001 year when he is passing the second clock.

OK.

[hamdani yusuf (OP)]

I asked Google Bard, what's the best explanation to the twin paradox?

Interestingly, it also suggest "Search related topics"
what's the best explanation to the twin paradox?
which brings to the link
https://www.wondriumdaily.com/is-the-twin-paradox-of-special-relativity-really-a-paradox/#:~:text=The%20twin%20paradox%20assumes%20that,sister%20who%20stayed%20on%20Earth.
and shows this diagram

The Mistaken Theory on Acceleration
The common response to this paradox, even from physicists who don?t work with relativity would be that the two twins are different as one of them experiences acceleration. According to this theory, Gabby experiences acceleration to catch up the speed, decelerates to turn around, and then again decelerates to land on Earth.

So, if acceleration is the answer, it means that while the spaceship is freewheeling between the stars, both twins age equally and when the acceleration turns on, there is instant aging. However, there is only one problem, this theory is incorrect.

It seems that Bard doesn't learn from the article that it suggests as one of the best explanation.

[hamdani yusuf (OP)]

Any thoughts about this?

Here's another video responding to those in the op.

The REAL Reason You Don't Understand Relativity

Think Relativity is confusing? Well, it's not just you -- even the experts can't seem to agree on its meaning, and often get basic facts about the formalism completely wrong. Here, we critique one such renowned professional who, in claiming to be clarifying the standardized theory of relativity, turns out to actually be promoting a misguided personal interpretation. What is this expert's confusion exactly, and why are such misconceptions so prevalent amongst the physics community?

Indeed, be cautious of posturers, gaslighters, stigmatizers, and Giordano-Bruno-burners who want to convince you that your inability to understand Relativity stems from your own deficient reasoning -- because when even the experts can't agree, you know there is something up...

Contents:
00:00 - Intro
01:11 - The Many Interpretations of Relativity
04:55 - Examining Sabine's Interpretation, Pt. 1
08:30 - Examining Sabine's Interpretation, Pt. 2
10:58 - The Source of Confusion
12:12 - Are There Better Interpretations?

Don Lincoln posted another follow up video, which seems to undercut the response video from Dialect above.
Does acceleration solve the twin paradox?

Special relativity is known to make mind-blowing predictions, perhaps most notably the Twin Paradox, in which two individuals claim that the other person?s clock is doing something funny. There have been many explanations, including two videos, one here on the Fermilab channel and one by fellow YouTuber Sabine Hossenfelder. These two videos seem to contradict each other, but they really don?t. In this video, Fermilab?s Dr. Don Lincoln explains how the two videos can be reconciled.

[Origin]

Google Bard is just a chatbot and not going to be very good for science other than just general info.

[Halc]

I asked Google Bard, what's the best explanation to the twin paradox?

Which is a good reason not to ask a chatbot for correct answers. It gave a terrible one. The bits about the history and the scenario are correct, as is the bit about the asymmetry, but asymmetry isn't the cause since two objects can take asymmetrical paths but still find their respective ages the same upon reuniting.
A good answer would be one that can be generalized, that isn't specific to this one particular case. It didn't give that.

The site you linked seems only relevant to instant-acceleration cases (discontinuous velocity), but to be honest I didn't read it. The diagram is accurate.
Please don't go to Sabine on this one. I've show that hers not only fails to generalize, but it is actually wrong. I find that horribly disappointing. She apparently doesn't peer review her videos before releasing them.

Origin's answers are spot on.

If the travelling twin brings a smaller clock which is synchronized to the earth clock at the beginning of the trip, what does it read when he's passing the giant clocks?

He ages ~130 days through the whole thing. That gets divided into 8 equal portions as the 8 clocks are 'passed'. From his point of view, it is the clocks that pass him, one every 16.3 days, not the other way around.

[hamdani yusuf (OP)]

Google bard is just a chatbot and not going to be very good for science other than just general info.

I think it will, eventually. And that won't be long, considering the exponential progress in AI. Even if Bard turns out to be a failure, its competitor will take its place. BTW, here's a message when I opened a new chat with Bard.

Bard is still in its experimental phase. Chatting with it and rating its responses will help improve the experience.

[hamdani yusuf (OP)]

The site you linked seems only relevant to instant-acceleration cases (discontinuous velocity), but to be honest I didn't read it. The diagram is accurate.

The diagram is similar to the explanation by Minutephysics.

Complete Solution To The Twins Paradox

This video is about the famous ?Twins paradox? of special relativity, how time can appear to be faster for two different observers at the same time, and which twin really is older (or younger) ? the one who stays on earth or the one who flies in a rocket ship to the stars?

REFERENCES

Muon lifetime and time dilation/relativity: http://hyperphysics.phy-astr.gsu.edu/hbase/Relativ/muon.html#c2
Paper on twin paradox under constant acceleration: https://arxiv.org/pdf/physics/0604025v3.pdf
Taking Cesium atomic clocks aboard airplanes: https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment

[hamdani yusuf (OP)]

If the travelling twin brings a smaller clock which is synchronized to the earth clock at the beginning of the trip, what does it read when he's passing the giant clocks?

He ages ~130 days through the whole thing. That gets divided into 8 equal portions as the 8 clocks are 'passed'. From his point of view, it is the clocks that pass him, one every 16.3 days, not the other way around.

So he sees the giant clocks tick faster than his onboard clock, both on going and return trips.
But that's not what the explanation shown by MinutePhysics' video.

[Origin]

But that's not what the explanation shown by MinutePhysics' video.

I come to the forum for discussions so I don't watch video recommendations.  If the video says that a clock (stationary relative to spaceship) located 1 ly from a spaceship traveling towards it at 0.999c would have an elapsed time other than 0.999 years when it passes the clock, then the video is wrong.  I doubt that is what the video says, but it could be a bad video.