How much of what we know is theory?

Drumpot

I watch a lot of documentarys because I find them fascinating... Just watching "seven ages of starlight".

I am curious as to how much of what we know about our solar system and universe is theory versus scientific fact..

It's hard for an average person to comprehend how they can go into so much detail by only being able to observe planets and stars from hundreds of millions of miles away..

Could pretty much everything that our most respected people's in this field think they know about the universe be Incorrect ?

ThunderCat

Drumpot wrote: »

I watch a lot of documentarys because I find them fascinating... Just watching "seven ages of starlight".

I am curious as to how much of what we know about our solar system and universe is theory versus scientific fact..

It's hard for an average person to comprehend how they can go into so much detail by only being able to observe planets and stars from hundreds of millions of miles away..

Could pretty much everything that our most respected people's in this field think they know about the universe be Incorrect ?

A bit of both I'd say.

With regards the solar system I would say we have an excellent understanding of what it consists of and the motion of the planets etc. We have sent probes to every planet in our solar system, we know how many moons each planet has, we have been able to establish due to meteorite falls that the asteroid belt between Mars and Jupiter is a remnant of the formation of the planets in the early solar system, we understand retrogrades of planets, elliptical orbits and the seasons here on Earth as a result, phases of the moon, ancient craters on the moon pointing towards the late heavy bombardment phase of planetary creation and the lack of atmosphere etc.

Further afield, we understand that we are part of a galaxy and that other galaxies exist consisting of billions of stars etc. We can see the composition of other stars and galaxies through spectroscopy and we know the universe is both expanding and came from a singularity due to the redshifting of galaxies.

We have made the observations that back up the maths.

But of course we don't know everything. We have to guess at what caused the big bang and exactly how the laws of physics break down inside a black hole. We know that what we can see only makes up a small percentage of what is out there and we have theorised that dark matter accounts for the difference. We have yet to tie in quantum mechanics with the mechanics of the very big.

But we know a lot, far more than we used to, and we will continue to learn more.

mickmackey1

On a superficial level we know a lot more than we used to, but recent discoveries suggest that up to 96% of the Universe consists of dark matter/dark energy, which are basically terms we've pulled out of a hat because we've no idea what they are.

So it's almost a case of, the more we learn the less we know.

Eugene Norman

Anything multiverse related is philosophy.

ps200306

Drumpot wrote: »

I am curious as to how much of what we know about our solar system and universe is theory versus scientific fact..

Not wanting to nitpick, but the term "scientific fact" is not used in science. Laypeople are usually being dismissive when they say something is "only a theory". But to the scientist everything is "only a theory". Science can't prove anything to be factual, it can only demonstrate that a description fits the observations, and over time the confidence that this will continue to be the case increases as more observations are made. But it only takes one counterexample to prove something wrong, or, as often happens, to prove that the description wasn't sufficiently general and has to change to take additional circumstances into account. When a theory survives for a long time, it sometimes starts being referred to as a "law", but that's really only shorthand for "a theory with a low ropiness quotient".

At any point in time, the theory -- assuming we have one -- always fits the observations, by definition. For instance, we assume that stars orbit around the centre of a galaxy at a rate determined by the collective mass of all the other stars in the galaxy. At least we did, until the measurements of the orbital speeds and the mass of the luminous matter turned out not to fit the law of universal gravitation. Then there was a choice -- change or abandon the law, or assume that there is far more mass than we can see, in the form of dark matter. Since the law was a cherished one that had stood the test of time quite well on a local scale, we decided instead to invoke invisible dark matter. Initially, it might have been non-luminous, but otherwise ordinary, matter distributed in a prolate spherical halo around the galaxy. Subsequent observations have ruled out both those things, so now we make increasingly esoteric guesses about what and where it might be. The facts still fit the theory ... but the theory could be as ropey as hell. However unsatisfactory, this situation is considered to be better than having no theory at all.

Another recent example is this week's Pluto flyby. Solid planets at the distance and size of Pluto would be expected to be inert. But the lack of impact craters makes it look like the surface of Pluto is young. We theorise that Pluto is not inert after all, because it's a better bet than that aliens have levelled it for playing golf. Again, the theory that Pluto is not inert fits the observations, but we haven't the foggiest how it has come about.

Basically, human nature abhors the vacuum left by the lack of a theory. So we always make one up, no matter how far-fetched. Otherwise we have mystery, and science is very uncomfortable with mysteries. It prefers nice solid explanations like atomic theory ... except that when we look more closely, even at familiar objects, it all starts to look mysterious on the scale of the very small.

Here's a a few mysteries in astronomy and astrophysics, for which we have made up pretty ropey theories.

Cork boy 55

Drumpot wrote: »

I watch a lot of documentarys because I find them fascinating... Just watching "seven ages of starlight".

I am curious as to how much of what we know about our solar system and universe is theory versus scientific fact..

It's hard for an average person to comprehend how they can go into so much detail by only being able to observe planets and stars from hundreds of millions of miles away..

Could pretty much everything that our most respected people's in this field think they know about the universe be Incorrect ?

How do you know you exist?

Rgb.ie

Cork boy 55 wrote: »

How do you know you exist?

I think, therefore I am.

Cork boy 55

Rgb.ie wrote: »

I think, therefore I am.

That's good. That's very good. But how do you know that anything else exists?

endacl

Everything we know is a theory. A scientific theory is not a "well that's just a theory" type of theory. It's important to get that distinction.

Rgb.ie

Cork boy 55 wrote: »

That's good. That's very good. But how do you know that anything else exists?

I don't and it can't be proven either. Spent time down that rabbit hole - not fun!

Cork boy 55

Rgb.ie wrote: »

I don't and it can't be proven either. Spent time down that rabbit hole - not fun!

Now, listen, listen. Here's the big question. How do you know that the evidence your sensory apparatus reveals to you is correct? What I'm getting at is this. The only experience that is directly available to you is your sensory data. This sensory data is merely a stream of electrical impulses that stimulate your brain. You really don't know what the outside universe is really like.

ps200306

Cork boy 55 wrote: »

How do you know you exist?

Rgb.ie wrote: »

I think, therefore I am.

Cork boy 55 wrote: »

That's good. That's very good. But how do you know that anything else exists?

Rgb.ie wrote: »

I don't and it can't be proven either. Spent time down that rabbit hole - not fun!

Cork boy 55 wrote: »

Now, listen, listen. Here's the big question. How do you know that the evidence your sensory apparatus reveals to you is correct? What I'm getting at is this. The only experience that is directly available to you is your sensory data. This sensory data is merely a stream of electrical impulses that stimulate your brain. You really don't know what the outside universe is really like.

My short answer to all of the above is: "consistency of experience". The sort of experience that says things fell toward the ground yesterday, and will almost certainly fall toward the ground and not the ceiling tomorrow. It would otherwise need a very elaborate explanation of how the mind not only conjures up an apparently orderly external world, but even fills it with apparently autonomous agents -- other people who seem to reason the same as me and report the same consistent experiences of the external world, even though both they and the world are illusory.

By choosing the simpler explanation -- that the external world is real -- we're also well on the road to science. Science uses inductive reasoning to formulate theories, to argue from the particular to the more general. In so doing it assumes that the simplest explanation that is consistent with the observations is probably the right one, and that the universe is subject to unifying principles (which, in a circular way, explains our consistent experience). Ockham's principle has stood science in reasonably good stead for centuries.

Of course, we have the problem that we have replaced our inexplicably consistent senses with an inexplicably consistent universe. Our acceptance of the latter explains more phenomena, but it's still a complete mystery as to why it is the way it is in the first place.

Drumpot

Cork boy 55 wrote: »

How do you know you exist?

I suppose it would depend on your definition of "exist".


I was watching another fascinating tedtalk on the conscious mind which is possibly the only way I can comprehend any concept of my existance. It was putting across the theory that everything has a conscious. Different level of consciousness, but just different levels.

I just find a lot of this stuff fascinating, thanks for all the responses.

Cork boy 55

ps200306 wrote: »

My short answer to all of the above is: "consistency of experience". The sort of experience that says things fell toward the ground yesterday, and will almost certainly fall toward the ground and not the ceiling tomorrow. It would otherwise need a very elaborate explanation of how the mind not only conjures up an apparently orderly external world, but even fills it with apparently autonomous agents -- other people who seem to reason the same as me and report the same consistent experiences of the external world, even though both they and the world are illusory.

By choosing the simpler explanation -- that the external world is real -- we're also well on the road to science. Science uses inductive reasoning to formulate theories, to argue from the particular to the more general. In so doing it assumes that the simplest explanation that is consistent with the observations is probably the right one, and that the universe is subject to unifying principles (which, in a circular way, explains our consistent experience). Ockham's principle has stood science in reasonably good stead for centuries.

Of course, we have the problem that we have replaced our inexplicably consistent senses with an inexplicably consistent universe. Our acceptance of the latter explains more phenomena, but it's still a complete mystery as to why it is the way it is in the first place.

You are false data.
Therefore I shall ignore you
False data can act only as a distraction. Therefore, I shall refuse to perceive. The only thing that exists is myself.

ps200306

Cork boy 55 wrote: »

You are false data.
Therefore I shall ignore you
False data can act only as a distraction. Therefore, I shall refuse to perceive. The only thing that exists is myself.

Another problem with solipsism is that you find that the objects of perception arrive unbidden, as if they were external and autonomous. Ignoring them doesn't make them go away. Kind of like Internet trolls.

mickmackey1

Cork boy 55 wrote: »

The only experience that is directly available to you is your sensory data. This sensory data is merely a stream of electrical impulses that stimulate your brain. You really don't know what the outside universe is really like.

It's definitely an interesting point, and one that's much overlooked. We look out and see stars and galaxies but is that only because we are perceptive to these 'datasets'? Maybe if we were wired differently we could detect a range of other stimuli, which would lead to alternative laws of physics etc.

ps200306

mickmackey1 wrote: »

It's definitely an interesting point, and one that's much overlooked. We look out and see stars and galaxies but is that only because we are perceptive to these 'datasets'? Maybe if we were wired differently we could detect a range of other stimuli, which would lead to alternative laws of physics etc.

Nowadays we're able to wire ourselves differently and convert lots of phenomena to things we can sense. We've enormously extended the range of EM wavelengths we're sensitive to, can sense gravity and nuclear forces, and can even feel the bumps caused by individual atoms.

But your point still stands. Things that don't interact well even with our extended detectors, such as weakly interacting neutrinos, are very hard to detect. If there was something that didn't interact at all, there could be entire other universes co-existing along side ours. Of course, without any interaction they could never make any difference to us, and so speculating about their existence might be more philosophy than science.

endacl

mickmackey1 wrote: »

It's definitely an interesting point, and one that's much overlooked. We look out and see stars and galaxies but is that only because we are perceptive to these 'datasets'? Maybe if we were wired differently we could detect a range of other stimuli, which would lead to alternative laws of physics etc.

The laws of physics are indifferent as to whether or not we are looking at them. Blind people fall over sometimes because gravity.