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?

[Jashwell]

[Replying to post 10 by stcordova]

The actual metric of spacetime is expanding, giving the illusion that we are in the centre.
It looks the same regardless of which point you take.

http://upload.wikimedia.org/wikipedia/c ... ies%29.png


As for 'special in the environmental sense', it is certainly common to see planets in the goldilocks zone of their solar system. We've found other planets that are, and we've seen very very few planets out of the number estimated in our galaxy.

Water is very common in the Universe. Hydrogen and Oxygen are some of the most common elements in the Universe. Carbon is also very common.
In fact, it goes like this for the milky way:
Hydrogen, Helium, Oxygen, Carbon

[stcordova]

The actual metric of spacetime is expanding,

That is open to serious debate.

Here is a good introduction as to why there should be some skepticism:


1. The easy version:
http://johnhartnett.org/2013/12/31/univ ... or-static/

2. The physics version:
http://arxiv.org/pdf/1107.2485v2.pdf


If space isn't expanding, then the "fingers of God" might really be pointing at us.

[Peter]

From the Wikipedia entry on the mediocrity principle:

astronomers reported, on 4 November 2013, that there could be as many as 40 billion Earth-sized planets orbiting in the habitable zones of sun-like stars and red dwarf stars within the Milky Way Galaxy, based on Kepler space mission data. 11 billion of these estimated planets may be orbiting sun-like stars. The nearest such planet may be 12 light-years away, according to the scientists.

Given these facts it's extremely difficult to argue that Earth is special. Can I prove that Earth isn't special? No more than I can prove a supernatural god doesn't exist.

[Jashwell]

[Replying to post 12 by stcordova]

Ignoring that "open to serious debate" means a single creation.com professor disagrees,

"
<doppler effect>
The question needs to be asked though, is this the same effect seen in the light from galaxies around us? Cosmologists today say, No! They interpret the observations differently. They say it results from the expansion of space–called cosmological expansion. "

It is the Doppler effect... from metric expansion. The mediocrity principle is a tautology, it's circular logic - it's just saying that you are more likely to pick the most likely outcome - while I don't know for certain that we aren't the centre of a static universe, I know it's very unlikely, and actually reasonable to believe that is not the case.

I also didn't see him address a collapsing universe (even in the paper), just dismissed it.
The mention of scripture doesn't bode well for serious scientific discussion.

He doesn't seem to be arguing that a non-expanding universe is reasonable so much as logically consistent and not eminently impossible.

I'm not a physicist so I'm not exactly qualified to comment on this, and I couldn't find a single review or response to the paper (or a mention outside of creation websites).


If we were near "the centre of the Universe"... that would be average.
Ironic that the word outlier should be so appropriate for the alternate case.

[stcordova]

The estimates of billions of habitable planets is based on the few we've supposedly seen. It's possible many of the few we've seen are illusions:

What astronomers thought were a pair of potentially life-friendly alien worlds are illusions, apparitions conjured up by a star's intense magnetic activity, a new study suggests.

These new findings could one day not only help astronomers dispel more such illusory exoplanets, but discover worlds that wo

http://www.space.com/26432-potentially- ... tence.html

Habitability is more than just an exo planet orbiting a star. Nasa has no information on many of the other requisites for life sustainability.

[Jashwell]

[Replying to post 15 by stcordova]

One pair of bad readings does not mean that it's plausible that most other findings invalid.
The actual requirements for life are unknown.

What's your actual argument?

[otseng]

The assumption that the earth is not in a special position actually cannot be proven.

A special position with respect to what?

stcordova explained it here.

Your claim that the cannot be "proven" to not be in a special position is no different from the claim that no one can prove that there isn't an invisible silent undetectable pink dragon in your basement.

It's just not my claim. I'm just quoting what Wikipedia is saying:

"The Copernican principle has never been proven, and in the most general sense cannot be proven, but it is implicit in many modern theories of physics."
http://en.wikipedia.org/wiki/Copernican_principle

And all for what? To support an ancient myth that some angry God had his corrupt priests incite the brutal crucifixion of his son so that you could be forgiven of your sins?

Let me ask you. Is it possible to have any conversation with you without having to listen to your constant rants against Christianity? I'm trying to have a respectable scientific discussion here. There's no need (at least not yet in this thread) of complaining about Christianity.

And finally, what you are suggesting is not even scientific. Instead of looking at known observed data and then just accepting what the data tells you, you are working backwards with the preconceived bias of wanting the Earth to be special in the hopes of supporting an ancient fairytale.

Actually, I have not even made the claim that earth is special in any way. I'm just challenging the assumption that the earth is not special.

[otseng]

You can't just point to sentient life on Earth and claim that we don't see this anywhere else, because we don't have the ability to say that life doesn't exist on other planets in this universe.

We have no evidence of any life elsewhere in the universe. Therefore, life only exists on Earth. Conclusion, Earth is special because it is the only place we know of in the entire universe where life exists.

But, if one holds to the mediocrity principle, this cannot be accepted. There must be life elsewhere. Yet, no evidence exists for life existing elsewhere.

[Jashwell]

[Replying to post 18 by otseng]

You keep saying "if one holds...", this isn't what it's like.
The fact and tautology of the mediocrity principle is that it's more likely to be usual and regular. Not that we are definitely the most likely outcome.

Not to mention that whether or not we're privileged in one respect doesn't mean we're privileged in another, nor that mediocrity is wrong.

[stcordova]

I previously said there are two notions of privileged:

1. spatial (geometric)
2. environmental

I forgot to add one, becuase there is yet another notion of privileged

3. temporal

That is to say we live in a privileged time. The Earth will not always be hospitable to life, but the Earth is "coincidentally" habitable at just the right time in cosmic history. We have a number of coincidences that would not be expected to be happening simultaneously:

Ever since Copernicus evicted Earth from its privileged spot at the centre of the Solar System, researchers have embraced the idea that there is nothing special about our time and place in the Universe. What observers see now, they presume, has been going on for billions of years — and will continue for eons to come.

But observations of the distant reaches of the Solar System made in the past few years are challenging that concept. The most active bodies out there — Jupiter’s moon Io and Saturn’s moons Enceladus and Titan — may be putting on limited-run shows that humans are lucky to witness. Saturn’s brilliant rings, too, might have appeared relatively recently, and could grow dingy over time. Some such proposals make planetary researchers uncomfortable, because it is statistically unlikely that humans would catch any one object engaged in unusual activity — let alone several.

The proposals also go against the grain of one of geology’s founding principles: uniformitarianism, which states that planets are shaped by gradual, ongoing processes. “Geologists like things to be the same as they ever were,� says Jeff Moore, a planetary scientist at the NASA Ames Research Center in Moffett Field, California. The unchanging world is “philosophically comforting because you don’t have to assume you’re living in special times�, he says.

But on occasion, the available evidence forces researchers out of their comfort zone. Here, Nature looks at some of the frozen worlds that may be putting on an unusual spectacle

http://www.nature.com/news/planetary-sc ... ct-1.12324

Further if we were alive in another time in universal history, would actually be making errant observations.

On this episode of ID The Future, CSC's Casey Luskin interviews noted Iowa State University astronomer Guillermo Gonzalez about the announcement of a forthcoming cosmology article by Lawrence M. Krauss and Robert J. Scherrer (Case Western Reserve University, and Vanderbilt University respectively) titled The Return of a Static Universe and the End of Cosmology. The paper is already inviting a great deal of comment since it deals with the debate over the big bang and the static universe, and says extrapolating forward in time, in the future we will be incapable of determining the true nature of the universe.

According to Dr. Gonzalez the authors are saying that future observers will mistakenly believe they are living in a static universe since current measurement tools will not be available to them. At some point in the future the measurements we are able to make today will not be able to be made because of natural changes in the universe. This coincides with Gonzales' Privileged Planet hypothesis which in part says that not only are we in the right place in the universe to make important scientific discoveries, we are also in the right time in the universe.
http://www.idthefuture.com/2007/04/the_ ... c_uni.html

Additionally, we live at the right time to take advantage of our moon.

There is a final, even more bizarre twist. Because of Moon-induced tides, the Moon is gradually receding from Earth at 3.82 centimeters per year. In ten million years will seem noticeably smaller. At the same time, the Sun’s apparent girth has been swelling by six centimeters per year for ages, as is normal in stellar evolution. These two processes, working together, should end total solar eclipses in about 250 million years, a mere 5 percent of the age of the Earth. This relatively small window of opportunity also happens to coincide with the existence of intelligent life. Put another way, the most habitable place in the Solar System yields the best view of solar eclipses just when observers can best appreciate them.�

Gullermo Gonzalez