Cosmology and the mediocrity principle

[otseng]

The mediocrity principle is the philosophical notion that "if an item is drawn at random from one of several sets or categories, it's likelier to come from the most numerous category than from any one of the less numerous categories" (Kukla 2009).[1] The principle has been taken to suggest that there is nothing very unusual about the evolution of the Solar System, the Earth, humans, or any one nation. It is a heuristic in the vein of the Copernican principle, and is sometimes used as a philosophical statement about the place of humanity. The idea is to assume mediocrity, rather than starting with the assumption that a phenomenon is special, privileged or exceptional.[2][3]

http://en.wikipedia.org/wiki/Mediocrity_principle

Current cosmology assumes that the mediocrity principle is true. Our solar system, the earth, and humans are not special. But, is this assumption true? Why or why not?

[otseng]

Even assuming a Euclidean universe, what does geometric location have to do with the speed of star formation?

Discarding speed of star formation for now, would you agree with the argument that we are at the center of an Euclidean universe?

[otseng]

What exactly in cosmology assumes the mediocrity principle?

I already stated it in post 4.

"In physical cosmology, the Copernican principle, named after Nicolaus Copernicus, states that the Earth is not in a central, specially favored position in the universe."
http://en.wikipedia.org/wiki/Copernican_principle

"The cosmological principle [means that] the universe looks the same whoever and wherever you are."
http://en.wikipedia.org/wiki/Cosmological_principle

What scientific theories would change if the mediocrity principle was neither rejected or accepted?

That's a good question. And there's a lot to cover there.

It seems like you are attempting to shift the burden of proof. You make the vague claim that cosmology relies on the mediocrity principle (without showing how) then demand that scientists must disprove that the universe/solar system/earth/humans are special OR that scientists must prove the mediocrity principle without explaining why.

It's not a vague claim. Please read through the links I provided above about the Copernican principle and the Cosmological principle.

I'm not stating that cosmologists must prove the mediocrity principle. I actually agree that it's not provable. But, I do make the claim that the evidence points against the principle being true.

It seems what's actually going on here is that certain theists are unwilling or unable to make a valid argument about how the universe/solar system/earth/humans is "special" so as to imply a theistic god so they try to shift the burden of proof onto others for their failure.

If you would read through the links, I trust you will then retract this statement.

[otseng]

[Replying to post 25 by otseng]

SETI is a lousy experiment with its heart in the right place. For how many years of human existence have we transmitted signals in analog? Most all transmission is now digital. I expect that other life forms would move along about the same progression line. Unless SETI is listening in to the right place, during the very narrow analog window, it would detect nothing.

So, do you think other intelligent life do exist?

[Jashwell]

[Replying to post 32 by otseng]

The cosmological principle means that we believe the current laws of physics are actual laws that apply everywhere else.

If your argument depends on "the natural laws only apply here and nowhere else" then unfortunately your argument isn't going anywhere. Not to mention that this could literally be used to justify anything so long as it isn't here.

The mediocrity principle says that it's more likely to come from somewhere that it is more probable to come from. It's a tautology. Circular logic. Obviously if you're picking between a uniform distribution you're going to be more likely to pick the bigger category. It's a fact of mathematics.

Are you suggesting we shouldn't believe the most likely (by far) outcome?

[otseng]

[Replying to post 32 by otseng]

The cosmological principle means that we believe the current laws of physics are actual laws that apply everywhere else.

That's part of it. But it's not all of it. It also involves the distribution of matter in the universe.

"In modern physical cosmology, the cosmological principle is an axiom that embodies the working assumption or premise that the distribution of matter in the universe is homogeneous and isotropic when viewed on a large enough scale, since the forces are expected to act uniformly throughout the universe, and should, therefore, produce no observable irregularities in the large scale structuring over the course of evolution of the matter field that was initially laid down by the Big Bang."
http://en.wikipedia.org/wiki/Cosmological_principle

[Jashwell]

[Replying to post 35 by otseng]

Well yes, if you have the same forces acting everywhere, and you view from a sufficiently large scale, it will probably look homogeneous. It's not a certainty - there still CAN be irregularities, and because of gravity and dark energy these irregularities can accumulate. Not to mention that under BBT, small early irregularities would lead to massive late ones.

There's also the fact that the Universe might not be big enough or have enough matter for this to apply.

[Goat]

But you said, we are the only life existing that we know of "in the entire universe". The problem is that our current knowledge does not contain information about life the "in entire universe". So to say that we are the only life we know of "in entire universe", is purposefully misleading. It implies a level of knowledge that we don't truly possess.

OK, I'm not going to quibble about "in the entire universe". I'll simply state that according to what we currently know, there is no evidence of any (intelligent) life existing elsewhere. Would you agree with this statement?

I will also say that 'We don't have any evidence there isn't any (intelligent) life existing elsewhere either'. I would have to say 'We do not have the ability to do an extensive examination of even 1/100,000th of the stars in this galaxy alone , nor can we show that the method we are using is effective).

[Divine Insight]

OK, I'm not going to quibble about "in the entire universe". I'll simply state that according to what we currently know, there is no evidence of any (intelligent) life existing elsewhere. Would you agree with this statement?

I still feel that your claim is misleading and dishonest as it is phrased.

We currently do not know that there is no evidence of intelligence life existing elsewhere.

What we know is that we have not yet been able to examine the universe in great enough detail to know whether there is any evidence for intelligent life elsewhere or not. And that is an entirely different thing from knowing that there is no evidence for intelligent life existing elsewhere.

You statement makes it sound like we currently have reasons to believe that there is no evidence for intelligent life elsewhere in the universe. And that is certainly false.

Our current lack of technological abilities is not sufficient reason to be making conclusions about things we can't yet determine.

[FarWanderer]

Even assuming a Euclidean universe, what does geometric location have to do with the speed of star formation?

Discarding speed of star formation for now, would you agree with the argument that we are at the center of an Euclidean universe?

I don't know. It's not my area of expertise. You haven't convinced me, but again, I still don't even see why it's relevant that you do.

I'll entertain you for now, but know that I do so under protest. After dragging me through this rabbit hole, your answer had better be good.

A key point was raised by stcordova:

If the Big Bang is true the universe is geometrically structured under a non-Euclidean geometry that obeys the Roberston-Walker-Friedmann-Lemaitre metric -- that means the universe has no center.

If the universe on the other hand follows something like a Euclidean geometry (the one that is most familiar to everyday life), then we may potentially live in a privileged location.

Does the universe as a whole have a Euclidean geometry or a non-Euclidean geometry?

Actually, evidence points to the universe having a Euclidean geometry. The only reason people believe it has a non-Euclidean geometry is the assumption of the mediocrity principle.

Measurements determine that the universe is Euclidean (flat).

Euclidean universes are flat. Not all flat universes are Euclidean.

Why should we believe a flat universe is a Euclidean one?

"Recent measurements (c. 2001) by a number of ground-based and balloon-based experiments, including MAT/TOCO, Boomerang, Maxima, and DASI, have shown that the brightest spots are about 1 degree across. Thus the universe was known to be flat to within about 15% accuracy prior to the WMAP results. WMAP has confirmed this result with very high accuracy and precision. We now know (as of 2013) that the universe is flat with only a 0.4% margin of error."
http://map.gsfc.nasa.gov/universe/uni_shape.html

Leaving an infinite number of possible non-zero values, all of which would deny a genuinely flat universe.

If the universe is flat (Euclidean), then the next question is what shape is the universe? More than likely, it would be a spherical shape if it expanded from a single point of origin.

If the universe is a sphere, then the next question is where are we in this sphere? Being in the center would account for the appearance of isotropy and homogeneity.

Even assuming a center, should we expect not to see isotropy and homogeneity from a non-center location?

If we are at the center, then all of the matter of the universe would've expanded from our location. Thus, it can be possible that our solar system formed before distant stars formed.

Still a non-sequitur.

[otseng]

I will also say that 'We don't have any evidence there isn't any (intelligent) life existing elsewhere either'. I would have to say 'We do not have the ability to do an extensive examination of even 1/100,000th of the stars in this galaxy alone , nor can we show that the method we are using is effective).

It's not just us actively looking for ETs. But, ETs have not been contacting/visiting us either. This is expressed in the Fermi paradox.

The Fermi paradox (or Fermi's paradox) is the apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilization and humanity's lack of contact with, or evidence for, such civilizations.

According to this line of thinking, the Earth should already have been colonized, or at least visited. But no convincing evidence of this exists. Furthermore, no confirmed signs of intelligence (see Empirical resolution attempts) elsewhere have yet been spotted in our galaxy or (to the extent it would be detectable) elsewhere in the observable universe. Hence Fermi's question, "Where is everybody?"

http://en.wikipedia.org/wiki/Fermi_paradox