[NMNeil]

Rolebama just posted a fantastic photo of the moon, which reminded me of a Youtube video that shows just how insignificant we all are and how vast the solar system is.
Fast forward as it can be boring, but remember you will be traveling at about 186,000 miles per second!

[Mark07]

Years ago, I watched a documentary that showed the scale of the sun compared to the rest of the solar system. It then went on to show how insignificant our sun was compared to other stars across the milky way.

Our scales of speed and distance are inadequate for the solar system, let alone the galaxy.

[Drivingforfun]

I can't watch the video at the moment so it might say something about this already

But, I found it interesting about how there is the speed of light which is basically a physical speed limit on any object with mass (even a single atom)

If an observer was looking at Earth for example 2000 light years away, they would actually be seeing Earth in the year 24 AD, because they'd only just be receiving the light that'd taken 2000 years to arrive

If they COULD exceed the speed of light and they could arrive to Earth, for example if they could travel at 2 times the speed of light they could travel 2000 light years in 1000 years, so they would arrive at Earth in the year 1024, would they arrive in medieval times or would it literally just be impossible??

[Mark07]

Would they not be viewing the earth at 24AD, but arrive 3024 (1000 years from now)?

[Drivingforfun]

That seems more like it Mark 😆

Maybe the opposite is true?? I read something about people aging more slowly if they travel really fast, i.e. close to the speed of light

We are talking billionths of a second if you go in the fastest airplanes but if you could approach the speed of light the time elapsed for the person going fast slows towards zero

If you stuck someone in a capsule and set them at an incredible speed for 10 years, they wouldn't age by a full 10 years when they came out

Or something 🤔

[Rolebama]

Whatever time they arrived, would they not just turn around and go home? I think if they were that advanced, they would. Unless the US military killed them!?

[NMNeil]

The theory of special relativity was explained to me in such a simple way that even I could understand it, eventually.
Imagine you are on a spaceship traveling away from the Earth at the speed of light.
On the ship is a clock and you are able to see in real time an identical clock on Earth.
Relative to you the time on the ship moves normally, but the light from the clock on Earth can't catch up with the ship, so as far as anyone on the ship can see, time is standing still on Earth, but for the people on Earth it's moving normally. And if you go faster than the speed of light you start to catch up with the light that came from the clock in the past, and it starts running backwards
Took a while to get my head around the concept.

[olduser]

For strange thoughts try Quantum Physics, Atoms are made up of a core of Protons with Electrons in orbit rather like a miniature solar system, that is fine...
But the Protons are only probably in the centre and similarly with the Electrons, they could be elsewhere at the moment they are observed, and observing them makes them shift anyway.

When you finish thinking about that try this, matter, say the chair you are sitting on, is made of Atoms but on an atomic scale, the atoms, that are only probably there, are mostly empty space, so the chair is mostly empty space but don't worry it's probably there.

Finally, all this lot has been worked out by human brains, and human brains are working out just how human brains work.

Actually, recently we (humans) have constructed a computer model with all connections of a houseflies brain, the next step is to trace all the internal connections.

I think I need a cup of tea now.
bearing in mind the cup will probably be there, and if the water molecules are bigger than the spaces in the atoms in the cup material it will hold hot water, oh I give up.

[Mark07]

Originally Posted by olduser

[...] When you finish thinking about that try this, matter, say the chair you are sitting on, is made of Atoms but on an atomic scale, the atoms, that are only probably there, are mostly empty space, so the chair is mostly empty space but don't worry it's probably there. [...]

A neutron star is definitely, mostly, there

[NMNeil]

A Youtuber, Mr. Alan Becker posted a series of videos using animation to explain physics, math etc.
Here's a video which explains Mr. Becker's video, which has me scratching my head in the last few minutes when he gets to quantum mechanics

[olduser]

Originally Posted by NMNeil

A Youtuber, Mr. Alan Becker posted a series of videos using animation to explain physics, math etc.
Here's a video which explains Mr. Becker's video, which has me scratching my head in the last few minutes when he gets to quantum mechanics

It's good or understandable up to the Quantum stuff, and I think String Theory is in there near the end.
Most of it relates to our experience of the world which of course doe's not include things at the speed of light, so it is almost intuitive.

I have seen other animations, and one thing that irritates me in them is they often depict rockets firing but describe the rocket moving at a steady state?

As I understand it, if there is a pressure difference in the rocket the rocket has to accelerate, (max pressure is opposite the outlet of rocket giving a forward force) unless of course there are other forces on the rocket, say gravity, solar particles?

I couldn't get the video to go full screen, I am going to find it on You Tube and try again.

But once we get near the speed of light my maths has petered out, so I have to rely on someone's interpretation of the maths.

I promised myself when I retired I would pick up where I left maths but there's always other things to be done, and as time goes by the residual knowledge creeps further and further back...

[NMNeil]

Originally Posted by olduser

I promised myself when I retired I would pick up where I left maths but there's always other things to be done, and as time goes by the residual knowledge creeps further and further back...

I'm the same.
I've always had an interest in electronics, but when it comes to the maths part, I wished I'd paid more attention at school.
A 'simple' integrator circuit for example
https://eng.libretexts.org/Bookshelv...3A_Integrators
I'm slowly getting a grasp on the math, but it's an uphill battle without first knowing the math leading up to this.

[olduser]

Yes, I looked at the extract, and found it frustrating but I think it is common with technical literature.
It's written for those that know but if they know that much they have no need to read it.

The math's is a problem, I have certainly forgotten how to deal with derivatives these days, and I couldn't claim to be happy with them when I thought I knew!

I know the only answer is to go back to a level that I still understand but I know it's going to hurt. 😥

It is difficult for someone who knows, to write for those with less knowledge, because the writer has forgotten what it was like to not know.

It's like the teachers and lecturers who say, "if you don't know ask".
Erm, if I don't know, how do I know what to ask?

[Rolebama]

It must have been around 65yrs ago that I learnt that nobody, or anything, is here. We only used to be.
As we only see reflected light, whatever reflected light we see took time to reach us, and our brain to interpret, so we can only ever see what was.

An insult which I liked: "It took all that time for sunlight to reach the planet, and you got in it's way."