Is there anything smaller than a partical/quark?

[JamesF]

There seems to be real misunderstanding of the word theory when used by scientists. “Theory is a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment.”

Not helped by the fact that those who want to believe a different point of view use the argument "it's only a theory" when trying to discredit the science. Which should obviously be met with a response along the lines of "If you're unable to comprehend that what scientists mean by the word 'theory' is not the same as a layperson in the first place, then it seems unlikely that you will be able to provide any well-reasoned alternative hypothesis".

James

[sonic190178]

so what about assumptions in scientific theory there not testable but are accepted without evidence

[JamesF]

so what about assumptions in scientific theory there not testable but are accepted without evidence

For example?

James

[sonic190178]

they say there is no centre to to universe , no privileged observer in the universe ,the universe is not spining?

[JamesF]

The first I have covered in response to your question elsewhere. It's a useful working hypothesis. It may not be true, but if it isn't, we can't tell. There's no evidence to contradict it. It isn't fact, it's just the best we've got.

That there can be no privileged observer I believe falls out of Einstein's work. That works, predicts stuff we can test, explains stuff we can see, so it's a reasonable step to say "if the theory is holds true and is consistent and the theory says there can be no privileged observer, then there can't be a privileged observer". if you think there can be a privileged observer then you'd need to come up with a way to explain our observations and make predictions as well as Einsteinian physics that also allows for one. And then it still probably falls by Occam's razor. You'd also need to demonstrate that the privileged observer is required, and that your new theory predicts testable things and explains things that Einstein doesn't.

Not sure about spinning universes. Doesn't ring any bells with me, that one.

James

[sonic190178]

1st there is no evidence to support that there is no centre to the universe

2nd i will start with are solar system earth is in a privileged postion ,are star is in a privileged postion in the galaxy if we were closer to the centre are view of the night sky would be vastly diffrent it would probably been a lot brighter we woulndnt see what we can here

on the universe scale if we was a near the centre of of the universe we would probably know it so we are probably located elsewere

but if we were located near the centre we would be a privilaged observer

[JamesF]

There's no evidence either way, as far as I'm aware. It's possible that the universe may have a centre, but if there's evidence for that then based on current theory it's beyond the observable universe so we'll never see it. That there is no centre is just the simplest explanation that fits the facts we can observe. It is only a hypothesis however, and not considered fact. So to answer your original question about why this is accepted in scientific theory, actually it isn't. It's one solution that's allowed by the theory and the simplest that fits known data therefore it's the one that gets used until evidence turns up that makes it impossible.

I think you're going to have to explain what you mean by "privileged observer" because it's certainly not what I understand by it and I can't work it out from what you've written. From the point of view of Einstein, a "privileged observer" is someone who has an absolute position in spacetime and against whom all others could be measured. Special Relativity doesn't allow one.

James

[sonic190178]

if there is a centre to the universe and you were located near the centre you would in fact be privileged observer because you would know there was a centre

[JamesF]

if there is a centre to the universe and you were located near the centre you would in fact be privileged observer because you would know there was a centre

So your definition of "privileged observer" is "someone who knows where the centre of the universe is"?

James

[astrofox]

James said it in a nutshell "When you step into the world of particle physics you have to leave all your preconceptions at the door. Different rules apply."

[sonic190178]

if the obsever knew there was a centre then he probably wouldnt need dark energy to make sense of his observations

[JamesF]

if the obsever knew there was a centre then he probably wouldnt need dark energy to make sense of his observations

And your evidence for that is what? Or are you just assuming it without it being testable?

James

[sonic190178]

but so are they

[JamesF]

I have already demonstrated that "they" aren't in the case of the universe having a centre. You appear to have wandered from clarifying what you mean by "privileged observer", so I can't do much more about that one.

James

[sonic190178]

my point is if you build a model and it dosent work without adding dark energy that is untestable then maybe we should make a new model that has a centre and see if that can explain it

[JamesF]

Well, if you think that's what should happen then maybe you should be the one who does it. Perhaps someone already has, and found it doesn't work. Or perhaps cosmologists see no reason yet to throw out the current model since it works so well for so many other things, and will work on researching and refining the concepts of dark matter and dark energy until they're understood well enough to fit into the model, or render the model invalid and require a new one.

James

[sonic190178]

well i will test it if some one wants to lend me a couple of billon pound

[Auntystatic]

All we should be asking here is, is the center of the universe smaller than a particle or quark?

Anything else in this thread is irrelevant!

Anyway I always thought quark was a bar keeper he was small.

[JulianO]

well i will test it if some one wants to lend me a couple of billon pound

People (or more often funding comittees) don't hand out a couple of billion pounds to someone who says I have a hypothesis I#'d like to test. They like to know exactly what the hypothesis is that you want to test, and exactly how you're going to go about testing it, and what the results will look like.

So the first step is to come up with a workable idea to test, then we can start to talk about financing it.

So - what would be your plan for testing that we are at the centre of the universe, or that the universe has a centre? Ideas are cheap!

[sonic190178]

People (or more often funding comittees) don't hand out a couple of billion pounds to someone who says I have a hypothesis I#'d like to test. They like to know exactly what the hypothesis is that you want to test, and exactly how you're going to go about testing it, and what the results will look like.

So the first step is to come up with a workable idea to test, then we can start to talk about financing it.

So - what would be your plan for testing that we are at the centre of the universe, or that the universe has a centre? Ideas are cheap!

i was being funny to jamesf comment

and i think anyone on here really doesnt needs telling about what you need to do to get funding

ideas are cheap

so have you got any ideas on this?

[JulianO]

My view so far, is there is no centre of the universe, because there is no evidence to suggest there is. The universe looks isotropic and homogeneous on large scales no matter what direction we look. Given the vast number of galaxies, never mind stars, it would be incredibly lucky to be on a single galaxy in the middle of the universe, and thats without all the supporting evidence.

[Auntystatic]

Just an update on my post from page one, I have now had confirmation that I am registered for s104 exploring science, the first course for my degree in astrophysics, :grin:

[JulianO]

Just an update on my post from page one, I have now had confirmation that I am registered for s104 exploring science, the first course for my degree in astrophysics, :grin:

Excellent - a great course - but quite a long one. You'll know lots about lots by the end!

[JamesF]

Indeed. Good news.

James