The biggest obstacle of science is "knowing" before we know

DaveC426913

In fairness to WW, it sounds like he's realizing his understanding of science has been polluted by pop sci, and that he's come to the right place to get cleansed.

DaveC426913

I hope you don't mean by example!

WW_III_ANGRY

Theories are based off facts, but how could there be such a thing if scientists don't claim knowledge as stated previously in this thread?

WW_III_ANGRY

Absolutely not you, no :)

WW_III_ANGRY

Either way how can the universe expanding be a fact?

DaveC426913

Noi, theories are based off observations. Sometimes observations can be interpreted in new ways.

DaveC426913

It isn't, in the strict sense that you're asking. The redshifting of light, and about a zillion other observations that corroborate it, give us confidence beyond virtually any amount of doubt that the explanation for our observations are that the universe is expanding. It is as factual as it is possible to be without actually having an armspan of several billion light years.

How do we know the sun is a ball of fusing hydrogen? Are you prepared to stay at square one, being unable to build an understanding of the cosmos because you're not willing to accept the the sun is powered by fusion?

WW_III_ANGRY

Its possibly a mass of fusing hydrogen that more than likely heats up our planet :)

Kittel Knight

I am with you!

They say universe is expandig. So, it is bounded.
Well, if the universe had a boundry, what would exist outside ?
So, this empty space would be part of the universe,too.
So the universe can not have a boundry!
So, it is not expanding.

I accept the galaxies are getting apart from each other, but is not the same to say the universe is expanding.
And the vacuum? The galaxies are part of the universe, but the universe is much more than celestial bodies.

Who are they trying to fool?
I understand you perfectly!

ZapperZ

Even though this is in the Philosophy forum, the PF Guidelines are still enforced on here, so pay attention to it before you make your post. It is fine if you disagree with the philosophical idea of something. However, if you are contradicting the science aspect of it and all you have as "evidence" are your personal preferences or you're making things up as you go along, then this is no longer acceptable based on our guidelines.

Zz.

DaveC426913

Is an expanding balloon seen as bounded by the ants that walk around on its surface?

DaveC426913

Yes, in the same way that's possibly a tree that more than likely will stop my car quite suddenly.

If we can't take direct observation as fact, what's left? (Ask Descartes.)

Lord Ping

If and only if it is true that the universe is expanding.

That's at least a working definition of a fact. Your next question will probably be: "How can we know that the universe is expanding? How can it be a known fact?"

Answer: if we have epistemic reasons to believe that it is true that the universe is expanding.

This will be the case if there is accepted data that an expanding universe hypothesis, if true, would best explain.

Kittel Knight

Hi Dave,
I think a better example would be "criatures made of shadow", or criatures who has only 2 dimensions, like shadows.
They live on the ball's surface - a 2d world - and, of course, they can not understand a 3 dimensional space.

The consequences?

Well, if one of them goes always straight (c'mon he is a shadow, and he will be on the surface along all the trip), he will be back after some period of time.
Although he has made a curve in a 3d space (our space, as we understand it), he has no idea of that. It is completely impossible to him this understanding.

So, if his universe (the ball's surface) is expanding (the ball's radius is increasing) , then the trip will be longer.

Of course, objects (shadows again) displaced on the ball's surface ("celestial bodies" in his universe), would be getting apart from each other.

And he could notice that.


Maybe this can help WW...

DaveC426913

Yes, the point here is that an "unbounded" universe does not require an "infinite" universe.

russ_watters

You're still using words you don't seem to understand. You'll need to clear up your understanding of the word "knowlege" now too. Here it is: So all "knowledge" implies is that someone has done an experiment and gathered some data. That's it. That's perfectly in line with the scientific method. You seem to think that the word "knowledge" implies some absoluteness/certainty (and this is a key to your misunderstanding of all of these scientific principles). It doesn't.

The biggest problem you have here is you are stumbling over your own preconceptions about how things work. You need to stop using those preconceptions and learn instead how these things actually work. That starts by learning the vocabulary of scientists. After learning the vocabulary, then you can start on the procedure (ie, the scientific method). This is an entirely new way of thinking/looking at the world for you. It will take some effort for you to understand these things, but trust me, it is worth understanding.

russ_watters

Further up on the page, I stated that all data has an error margin associated with it. I said such things are "factual in nature" and the associated margin for error is part of the "fact". So when it comes to the expansion of the universe, the statement would look something like this:

"The data that scientists have points to a 99.9% certainty that the universe is expanding."

That entire statement is one fact. When people talk about these things at parties or on the evening news, they drop the error margins from the statement because it makes the statement less cumbersome and laypeople don't understand it anyway. Do not confuse that to mean scientists have an absolute certainty about the issue.