andrew s

1 minute ago, saac said:

Yes they do but you don't build and operate a particle collider without Newtonian mechanics  - stress, strain, acceleration, momentum, compression, expansion, cooling, fabrication of steel , concrete, generation of electricity etc. 

Jim 

 

If you want to frighten a quantum physicist ask them about the measurement problem.  🤫😉😊

Regards Andrew 

@saac the hot topic area would be quantum computing. Also solid state chip design is hitting the limits set by QM. Regards Andrew 

I did until a few weeks ago when I retired from serious observing.  Regards Andrew 

1 minute ago, saac said:

Hang on don't go dissing Newtonian dynamics here     Can you tell I am a fan boi - stands up and mutters to the group  "I'm Jim and I'm an engineer.  It's been 32 days since picked up a slide rule " 

We came a long way on the back of Newtonian mechanics - heavier than air flight, split the atom, left the planet, built CERN and found more quantum stuff, put JWST in space to see the beginning.   Not so bad for "special cases" - we inhabit that realm.  Let's hear it for Newton.   

Jim 

Absolutely,  the classical world is our domain. It is the bumps and bruises of our experience with Newton's insights that forged our world.

It is the lack of connection to our experience that make relativity and QM strange and mysterious. Open to our prejudice and fantasies. 

Regards Andrew 

13 minutes ago, Xilman said:

I have a degree in chemiastry, for instance.

We can't all be perfect 😊 Regards Andrew 

13 minutes ago, teoria_del_big_bang said:

Well considering it is the one and only post from the OP it has certainly stirred everybody up 🤣

Steve

A legacy few can aspire to. Regards Andrew 

30 minutes ago, ollypenrice said:

I'm convinced we need a more generalized theory of time.

I have spent a life time reading about and trying to understand time. Alas I am none the wiser.

I have a bookshelf full of tomes on the topic from psychologist,  philosophers and physicist each with there own take on it.

It is enigmatic in the extreme,  you can only measure it via a clock of some sort, it is not an observable in QM unlike space.

However,  it is the one continuous parameter that spans GR, SR and QED without modification.  

I had reached a similar conclusion to you that t = 0 does not exist just as the ends of an open interval on the real line don't include the end points.

In GR singularities are outside our space time - you are spot on there.

In the end I am left with what Einstein's I said "time is what a clock measures "

Regards Andrew 

Just now, wesdon1 said:

feel they're blindly loyal to GR because it explains a lot of what they see so so well. But just like in ancient times, there's anomalies with their theories, notably when you get down to the quantum level of mass and energy, and gravity etc. 

Well it also predicted thing we had not seen before. The bending of light by mass and  frame dragging are too good examples.  

It also has an elegant solution to dark energy namely the cosmological constant representing  a minute net curvature of space time. (Not all scientists accept it though.)

If you follow the literature you will see many many papers on modification or alternatives to GR and or MOND type theories. The test is to find one that explains all GR does and more.

We are still waiting.

There is no blind loyalty every scientist working in this area would love to get the next Nobel prize for unseating GR.

Ripping up the book and starting again is very hard.  I think that's what string theorists tried to do. To my mind the issue is we have very good theories that for all practical purposes meet our needs. What we lack is experimental results that force a change  in thinking like the MM aeither experiment and the discovery of wave particle duality. 

Regards Andrew 

Here is an example of lens focus

Regards Andrew 

I have been looking for a reference without success.  I think it depends on the scope. The simplest is to move the prisms back and forth but I don't think that is possible with a roof prism design.

Regards Andrew 

PS beat me to it 😊

Moves internal lenes. Think like moving a Barlow in a normal scope. Some camera lenes do the same.

Regards Andrew 

1 minute ago, Macavity said:

It offers
CERTAINTY to non-scientists, rather than delights in uncertainty?

Absolutely,  the only certainty in life is death and taxes,  unless your rich enough to avoid the latter.😊

Regards Andrew 

10 hours ago, Ags said:

I know there are plenty of nonscientific explanations, but I want the sciency one.

Then I fear you will be forever dissapointed.  I see no likelihood that we will be able to probe the required energy regime. 

To expand slightly.  Cosmology needs two main components.  Firstly,  a theory of gravity and second an equation of state.

For the extremes required to described the initial state we don't have either. A quantum theory of gravity, if it exists, remains as illusive as ever and as I mentioned we have no way of seeing how matter and radiation behave in these circumstances. 

Regards Andrew 

8 hours ago, Ags said:

Yes but that 0.0001 s is the bit that counts.

Can you say why it's so important to you?

I don't think it can explain anything we can observe. Things like nucleosynthesis, the ratio of the initial nuclei, is already covered with what we can explain.

If you are not concerned with observable things then you don't need a scientific theory types others will do.

Regards Andrew 

5 minutes ago, Knighty2112 said:

Hi Andrew. Yes, after 50 plus years of trying to find that answer I realise that science doesn’t have an answer for that. Some are fine with that, but for me it just niggles away still trying to glean back in time and space past that initial inflation after the big bang and the formation of the universe we inhabit now.  

I am in that's ok camp. We can get to about t = 0.0001s of the start which is good in my view especially if you take it as a percentage of the period we do have a good theory for 0.0001s to 13.8 Gyrs

Regards Andrew 

@Knighty2112  the simple answer is we don't have a scientific theory for what you call the point of creation.  We have to stop when the temperature and density are so high that we don't have access to any data about that regime. 

Regards Andrew 

It might be worth listing the key software and kit I used.

Software

Voyager automation software - also linked to observatory provided weather / roof control

The Sky X telescope control and plate solving

Astroimagej calibration and photometry

VPN access software

Kit relevant drivers and access often via browser

Hardware 

Paramount ME II - robotic mount fails safe

Atlas focuser - electronic focuser

IP power switch - switching kit on and off as needed

UPS 

Back up disc system

Electronic filter wheel 

On Axis Guider

Cameras and telescope

People

Dave and Michelle at PixelSkies  - invaluable. 

Regards Andrew 

The best advice I can give is have it at a well managed site. It very easy to remotely turn off your PC rather than restart it. Good to have someone local to turn it back on.

Second best have a roof that can shut safely what ever the position of your scope.

Regards Andrew 

2 minutes ago, saac said:

"how do the balls know when to move and how many"

Yes, thinking deeply about simple cases is very insightful.  Try changing your frame of reference and have the s (normally)  stationary balls heading towards the the m (normally)  moving ones. Of course the kinetic energy and momentum in the two frames of reference are different. 

Regards Andrew 

It's a very good example of idealised physics.  Another is Newtons cradle. 

If one just looks at the math you can have solutions in which any one of the balls  moves off after the initial impact if you restrict yourself to Newtons 3 laws.

You need to add something about rigidity of the balls etc. to get the classical result. 

15 minutes ago, saac said:

Wait a minute, just a further thought, how does that reconcile with conservation of momentum? Or have read into it incorrectly!

Jim 

I don't think it does as the tangential forces does work on the ball.

Regards Andrew 

PS on reflection there are many cases in physics where there are multiple solutions most of which are rejected as being un-physical even though they obey all the relevant laws and satisfy all the equations. 

1 minute ago, ollypenrice said:

Here's a link to a lever with push-pull micro asjusters. I had one. It's not bad.

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p3286_TS-Optics-Microfocuser-for-your-camera-lens-up-to-135-mm-Diameter.html

Olly

I have one you can have foc .PM me if your interested. Regards Andrew 

2 minutes ago, SiD the Turtle said:

I haven't seen it impacting my imaging, but I'm curious as to what it is. Doesn't look like amp glow.

But, that us what it is in my view. Look at this.

Regards Andrew 

16 minutes ago, kurdewiusz said:

I answered: "It means, that the current time flow in the place of emission of background photons is much greater than ours. If the scale factor is retained, time dilation is retained as well."

I suspect I did not understand that either. In comoving coordinates there is no time dilation. 

Any way we go in circles.  

20 minutes ago, kurdewiusz said:

And don't think I will forget about a0/a = a(tr)/a(te) = 1 for a = 1 in case of the particle horizon calculation. I will keep reminding you this error, until we're done.

We are done.

Regards Andrew 

I have read and reread your concerns about the integration and I don't understand it. It seems metaphysical.

All the integration is doing is integrating the instantaneous comoving speed of light c/a(t)  over a time interval. 

It's just a integral version of distance = speed x time.

That different approximations and approaches lead to the same order of distance so that makes me secure the integration is fine.

If you look at my analytic solution for the matter dominated Universe you get 13.6 x 3 = 40.8 Glyrs

The paper I linked to got 42.6 Glyrs using a numerical integration

The pros get 46.5 Glyrs

So given the approximations that looks solid to me.

Regards Andrew 

I'll let others judge who is right. Regards Andrew