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?

[Divine Insight]

There is nothing dishonest about the statement, "based on our current knowledge, there is no other (sentient) life in the universe."

No that is not a true statement. It's provably false. We do not currently possess knowledge to make the statement that there is no other sentient life in the universe.

If we want to make a truly honest statement that conveys the truth, we must necessarily say, "based on our currently knowledge we are simply unable to be able to determine whether there is other sentient life in the universe or not".

That is truth.

To say what you have been saying, "based on our current knowledge, there is no other (sentient) life in the universe.", implies that we actually possess current knowledge that indicates that there is no sentient life in the universe. And that's simply not true.

Therefore to make such a statement under the pretense that it is actually a true statement is dishonest. Of course, it may not be "intentionally dishonest" on the part of the person saying it precisely because they don't realize that they they are actually making a statement that isn't true.

But it's a false statement no matter what.

Now, it's entirely possible that in the future we actually do have evidence of extra-terrestrial life from the SETI program (or any equivalent program). But, we've been trying to find evidence, and none has been found. We can tentatively conclude that none exist based on not finding any evidence.

No, that is where you are extremely wrong. Just because we haven't yet found any evidence does not mean that we can tentatively conclude that no sentient life exists.

The reason that this is the case is because the SETI program simply isn't able to actually make that determination.

Here's a statement from the SETI project itself:

Statement from SETI

The failure so far to find a signal is hardly evidence that none is to be found. All searches to date have been limited in one respect or another. These include limits on sensitivity, frequency coverage, types of signals the equipment could detect, and the number of stars or the directions in the sky observed. For example, while there are hundreds of billions of stars in our galaxy, only a few thousand have been scrutinized with high sensitivity and for those, only over a small fraction of the available frequency range.

They haven't even been looking outside our own galaxy much. I'm sure they have tried to listen for signals from very nearby galaxies but I imagine even that would be extremely difficult. Most of what they have been trying to do is listen for signal from other star systems in our galaxy.

I don't SETI is even prepared to conclude that there is no other sentient life in our own galaxy, much less the entire universe.

Pointing to SETI and proclaiming that we must conclude that there is no other sentient life in the universe, is clearly a false claim that SETI itself clearly does not support.

What if I likewise claim that it is dishonest for atheists to claim that god does not exist? Would that be acceptable? They claim that they've been seeking for evidence but none exist. Can I just retort that they're just making a dishonest statement?

I think that can be a fair assessment depending on what the atheists are actually attempting to claim. If they are trying to claim that there is not god simply because they haven't found evidence for one, then I think you are more than justified to have a truly wonderful belly laugh over that one and say to them, "Surely you're joking".

There is no reason to take that kind of argument seriously.

However, most atheists I know actually point to evidence that actually contradicts many religious claims. Most atheist I know also do not claim that there is no god. But instead they simply point out why various specific religions cannot be true. They might conclude that lack of evidence for a god is sufficient reason to not bother to believe in one. I can't argue with that.

But yeah, atheists who think they can logically rule out a god just because they haven't been about to find evidence for one are actually quite hilarious. I don't even think of them as being dishonest, I just think of them as being unintelligent.

~~~~~

By the way, getting back to the original point about sentient life in the universe. If you believe that the current lack of immediate evidence is "good enough for you" to jump to the conclusion that there probably isn't any, that's fine.

But if you're going to put than into a broad sweeping statement that sounds "scientific" by saying, "Based on our current knowledge,... blah blah blah"

Now you are making a statement that is clearly not true.

It's certainly not my current knowledge that there is no other sentient life in the universe, nor is it the current knowledge of the SETI project, nor is it the current knowledge of the scientific community as a whole.

So for you to say "Our current knowledge is,..." is a false statement since you clearly do not speak for these scientific communities.

That is not "our current knowledge" especially given the conclusion you have jumped to. Clearly SETI does not agree with your conclusion.

On the contrary, their view is "The failure so far to find a signal is hardly evidence that none is to be found."

That's a dramatically different conclusion than you have been claiming.

[Unhand Me Sir]

I find it very strange that my opponents keep questioning what is the universe and what is the beginning. Perhaps I should qualify it by saying "our universe". Our universe would include our space-time, matter, energy, and anything else that is bound by our space-time. The beginning would be the point where our space-time came into existence.

Here are some arguments to support finite matter/energy:
- If the universe is finite in age, then it could not have produced infinite matter/energy.
- If the universe has infinite matter/energy, then it would have infinite size.
- Since the universe is finite in age and not infinite in size, then the universe has finite matter/energy.

This kind of talk demonstrates the limitations of armchair cosmology.

It sounds obvious that something that is not infinitely old must have a beginning, but no boundary theories in which there is no point time=zero have been around for 30 years.

For more than a century physics has been adopting theories previously considered a priori to be obviously false, including some that can't be accommodated by classical logic. Our common sense, developed here in the middle scale of size and energy, is not a good guide to what happens on other scales.

It's important to bear this in mind, otherwise there's a risk of sounding like William Lane Craig, which I'm sure none of us would want.

[FarWanderer]

But since you seem to be making an argument here, I'll address it. Your implied argument, that "no reason to accept not A" makes for "reason to accept A", is fallacious. It's ignores the possibility of "no reason to accept not A" and "no reason to accept A" as both being true.

Here are some arguments to support finite matter/energy:
- If the universe is finite in age, then it could not have produced infinite matter/energy.
- If the universe has infinite matter/energy, then it would have infinite size.
- Since the universe is finite in age and not infinite in size, then the universe has finite matter/energy.

1) Who says the universe "produces" matter/energy at all? You are aware of the first law of thermodynamics are you not?

2) Yes, infinite matter/energy would imply infinite size, but since when have I accepted that the universe must not be of infinite size?

3) See above. In post 92 you were arguing that the universe cannot be infinite in size because it's not infinite in matter/energy. Now you are arguing that the universe cannot be infinite in matter/energy because then it would be infinite in size.

All I see is a hamster wheel in motion.

However, I need specific criteria to distinguish whether something is "bound to our space-time" or not. For example, when considering the additional dimensions proposed by String Theory, are these dimensions part of the universe, or is the universe part of them?

The additional dimensions of string theory would not be part of our universe according to my definition.

Do you offer another definition of universe?

I just want yours clear so I can properly answer your question.

And as for this "point" you refer to as "the beginning", it is a point in time, correct? Is this point in time bound by our universe, or are you positing an extra-universal dimension of time?

I'm not positing an extra-dimensional time. It would be T0 in our space-time.

Ok, well, the relevant equation in relativity divides by t. That means, according to relativity, that it's impossible for t=0 to be bound by our universe.

So, my answer then is "No". I don't think the universe has a beginning as you have defined it.

http://www.gizmag.com/universe-homogene ... ars/24149/

That's an interesting article.

Some points about the claim that the universe is homogeneous...

It points out that the data used for their study was only 1% of the sky.

"The data does not cover the entire sky, rather being restricted to less than 1 percent thereof, a patch measuring thirty by thirty degrees."

Sampling 1% does not demonstrate it's true for the whole.

Of course. But this is actual empirical data, rather than what you have (sheer intuition).

Looking at the paper itself, the study acknowledges that it indirectly assumes homogeneity.

"Certain parts of our analysis require the assumption of a cosmological model and, implicitly, homogeneity." (pg 3)

This would be begging the question.

That's a huge oversimplification. They talk about it quite a bit in section 7.

In fact, the only area in which you will ever find people who think that science has a complete understanding of how the natural world works is in apologetics.

Really? I find that to be quite an ironic statement.

It's also an ironic reality.

Here is what I claim. If the universe is non-homogeneous, then the only place it would appear to be isotropic is in the center.

I have absolutely no idea how you might justifiy this claim, especially in light of how we've already established that all points in the universe would appear isotropic with regard to redshift even assuming there were a center.

If the edge of the universe was within our light cone, then it would appear darker towards that side. Of course, this assumes the actual universe is not much larger than our observable universe, which we can debate next.

Oh. Another assumption. OK.

Yes. If the universe is equal to our light cone, we are at the center. Good for that.

I don't think you understand your problem. Your supposed heterogeneity would have to follow a specific pattern with respect to distance from the Earth, such as the regions nearer to Earth being proportionally more dense than the outer areas. Otherwise, any heterogeneity equally implies anistropy.

The universe may not be homogeneous in more subtle ways, but we'd sure as heck know it if it were heterogeneous in the flashy way that it would have to be in order for your scenario to fit.

[Replying to otseng]

You're trying to have it both ways. If absense of evidence is evidence of absense for aliens, then it's the same for God.

I never said that there was no evidence for God though. I only said that atheists claim that there is no evidence for God. So, it would be atheists that would have it both ways.

There isn't.

Any and all "evidence" for God would be just as good as evidence for aliens. You could say that God would be more "alien" than the aliens. At least aliens would actually be made of stuff we know exists.

[otseng]

If we want to make a truly honest statement that conveys the truth, we must necessarily say, "based on our currently knowledge we are simply unable to be able to determine whether there is other sentient life in the universe or not".

Instead of alien sentient life, let's replace it with something else. Suppose we talk about unicorns instead. We have no evidence that any unicorns exist. Can we say that none actually exist? Or do we have to say, "based on our current knowledge we are simply unable to be able to determine whether any unicorns exist or not"?

Just because we haven't yet found any evidence does not mean that we can tentatively conclude that no sentient life exists.

The reason that this is the case is because the SETI program simply isn't able to actually make that determination.

Here's a statement from the SETI project itself:

Statement from SETI

The failure so far to find a signal is hardly evidence that none is to be found.

Note that it says "none is to be found". I'm in agreement with that. It's entirely possible that some can be found in the future. But, it does not say, "The failure so far to find a signal is hardly evidence that no aliens exist."

I don't SETI is even prepared to conclude that there is no other sentient life in our own galaxy, much less the entire universe.

To be clear, I'm not saying that we need to abandon the SETI program. By all means they are free to continue to search for other intelligence.

Pointing to SETI and proclaiming that we must conclude that there is no other sentient life in the universe, is clearly a false claim that SETI itself clearly does not support.

I'm not making a final hard claim that no other intelligence exists. I'm making a softer claim. I'm claiming that based on the evidence so far, at this point, no other sentient life exists.

Of course the SETI program would never support the hard claim that no ETs exist. Otherwise it'd be kinda pointless for them to look.

What if I likewise claim that it is dishonest for atheists to claim that god does not exist? Would that be acceptable? They claim that they've been seeking for evidence but none exist. Can I just retort that they're just making a dishonest statement?

I think that can be a fair assessment depending on what the atheists are actually attempting to claim. If they are trying to claim that there is not god simply because they haven't found evidence for one, then I think you are more than justified to have a truly wonderful belly laugh over that one and say to them, "Surely you're joking".

There is no reason to take that kind of argument seriously.

OK, good.

So for you to say "Our current knowledge is,..." is a false statement since you clearly do not speak for these scientific communities.

I do not claim to speak for any scientific community. What I mean by current knowledge is the lack of detecting anything from other intelligent life, not that it's the position of any particular group.

[otseng]

It sounds obvious that something that is not infinitely old must have a beginning, but no boundary theories in which there is no point time=zero have been around for 30 years.

Could you go into more detail about this?

[otseng]

1) Who says the universe "produces" matter/energy at all? You are aware of the first law of thermodynamics are you not?

I'm not implying that the universe is constantly producing matter/energy. I'm just referring to the moment of initial "creation" of the universe.

2) Yes, infinite matter/energy would imply infinite size, but since when have I accepted that the universe must not be of infinite size?

What are your arguments for an universe of infinite size?

All I see is a hamster wheel in motion.

Do you agree that the universe is finite in age?

Ok, well, the relevant equation in relativity divides by t. That means, according to relativity, that it's impossible for t=0 to be bound by our universe.

What it means is that science is unable to address what happened at t=0.

In fact, the only area in which you will ever find people who think that science has a complete understanding of how the natural world works is in apologetics.

Really? I find that to be quite an ironic statement.

It's also an ironic reality.

It's not even reality. Which apologist claims that science has a complete understanding of how the natural world works?

Oh. Another assumption. OK.

Just as space is expanding is an assumption.

I don't think you understand your problem. Your supposed heterogeneity would have to follow a specific pattern with respect to distance from the Earth, such as the regions nearer to Earth being proportionally more dense than the outer areas. Otherwise, any heterogeneity equally implies anisotropy.

If regions nearer the earth were more proportionally dense, would it still not appear isotropic?

Any and all "evidence" for God would be just as good as evidence for aliens.

I don't know what you mean by this. You mean aliens can also account for the origin of the universe?

[Divine Insight]

I'm not making a final hard claim that no other intelligence exists. I'm making a softer claim. I'm claiming that based on the evidence so far, at this point, no other sentient life exists.

But that's still false. It's a conclusion that is totally unwarranted. There is no 'evidence' that no other sentient live exists.

Your statement makes it sound like we actually currently have evidence that no other sentient life exists. And that is simple false. It's not a true statement. Period.

This is why I say that it's a "dishonest" statement. It's a statement that is implying something that is clearly not true.

A true statement would be, "based on the evidence so far, at this point, we simply can't say whether other sentient life exists or not."

Now that's a true statement.

[FarWanderer]

1) Who says the universe "produces" matter/energy at all? You are aware of the first law of thermodynamics are you not?

I'm not implying that the universe is constantly producing matter/energy. I'm just referring to the moment of initial "creation" of the universe.

OK, but why does that even matter? Do you have any particular reason to believe the initial mass of the universe was "produced" by the universe, or, even assuming that it was, that it was finite?

2) Yes, infinite matter/energy would imply infinite size, but since when have I accepted that the universe must not be of infinite size?

What are your arguments for an universe of infinite size?

Your presupposition that I even have such arguments is incorrect, and it demonstrates that you weren't been paying attention when I expressed my position on this.

I've already made myself clear that I find neither a finite nor an infinite universe particularly intuitive. I don't necessarily deny that the universe may be finite in extent; but it's you who took it upon yourself to prove it. For my part I'm just pointing out that all your "evidence" amounts to nothing more than intuition and fallacious logic.

My problem with your universe has never been that it's finite; it's that it has an arbitrary border. My intuition screams "absurdity" at the idea, but I don't intend to argue the point because arguing over whose intuition is "better" is about the most pointless activity I can think of.

All I see is a hamster wheel in motion.

Do you agree that the universe is finite in age?

Yes.

Ok, well, the relevant equation in relativity divides by t. That means, according to relativity, that it's impossible for t=0 to be bound by our universe.

What it means is that science is unable to address what happened at t=0.

Can we agree that science does not affirm the existence of t=0?

In fact, the only area in which you will ever find people who think that science has a complete understanding of how the natural world works is in apologetics.

Really? I find that to be quite an ironic statement.

It's also an ironic reality.

It's not even reality. Which apologist claims that science has a complete understanding of how the natural world works?

Most of them. You, for example:

If it's a purely naturalistic explanation, matter would not even escape a black hole, so I do not think a purely naturalistic explanation is at play.

In order for this statement to be true, you have to assume the non-existence of any natural explanation, even an explanation we are unaware of.

And if you are assuming there exists no natural explanation we are unaware of, well, then you are assuming science has a complete understanding of how the natural world works.

Oh. Another assumption. OK.

Just as space is expanding is an assumption.

We are already discussing the merits of the cosmological principle, which if true would have the metric expansion of space as the best explanation for our observations.

You are free to argue the merits of the visible universe comprising most of the complete universe.

I don't think you understand your problem. Your supposed heterogeneity would have to follow a specific pattern with respect to distance from the Earth, such as the regions nearer to Earth being proportionally more dense than the outer areas. Otherwise, any heterogeneity equally implies anisotropy.

If regions nearer the earth were more proportionally dense, would it still not appear isotropic?

Not exactly sure what you are asking, but this will probably answer whatever your question is:

If the only way in which the universe lacked homogeneity was entirely relational to distance to Earth, the universe would appear isotropic from Earth. The most intuitive form this pattern would take would be that regions near Earth were more proportionally dense, although the inverse (closer = sparser) could also produce apparent isotropy without homogeneity.

However, with accurate distance measuring techniques, we could pretty easily check for this pattern at least as far out as we can measure. Since isotropy is assumed, to falsify this theory we'd only need to look in one direction and check whether density changes with respect to distance. If it doesn't, then the theory is false.

We do have measuring techniques and have done quite a lot of measuring in a variety of distances and directions, and through all of it I've never even heard of a density pattern that occurs with respect to Earth, so I'm pretty sure none exists.

Although... as long as you are playing the hyper-skeptic, you could question the validity of our measuring techniques, but I don't think you can do so without dismissing an assumption that's critical as support for the universe having a beginning.

Any and all "evidence" for God would be just as good as evidence for aliens.

I don't know what you mean by this. You mean aliens can also account for the origin of the universe?

Wasn't really thinking about the origin of the universe... but sure, why not?

[otseng]

A true statement would be, "based on the evidence so far, at this point, we simply can't say whether other sentient life exists or not."

Now that's a true statement.

You did not address the example of unicorns.

Instead of alien sentient life, let's replace it with something else. Suppose we talk about unicorns instead. We have no evidence that any unicorns exist. Can we say that none actually exist? Or do we have to say, "based on our current knowledge we are simply unable to be able to determine whether any unicorns exist or not"?

Should we also say, ""based on the evidence so far, at this point, we simply can't say whether unicorns exists or not"?

[otseng]

Do you have any particular reason to believe the initial mass of the universe was "produced" by the universe, or, even assuming that it was, that it was finite?

Where did I say the universe was produced by the universe?

2) Yes, infinite matter/energy would imply infinite size, but since when have I accepted that the universe must not be of infinite size?

What are your arguments for an universe of infinite size?

Your presupposition that I even have such arguments is incorrect, and it demonstrates that you weren't been paying attention when I expressed my position on this.

I know that you stated you have no arguments for an infinite universe. Yet, I have given arguments for a finite, so wanted to give you another chance. If you have no arguments for an infinite universe, and I do have arguments for a finite universe, would you agree that it is more reasonable to accept a finite universe?

For my part I'm just pointing out that all your "evidence" amounts to nothing more than intuition and fallacious logic.

I don't think it's fallacious to accept a finite universe, in light of the fact that you nor anybody else is arguing for an infinite universe and I have already given arguments for a finite universe.

My problem with your universe has never been that it's finite; it's that it has an arbitrary border.

Yes, there would be a boundary with a finite universe. Does it intuitively seem absurd? Perhaps. But, I think it naturally follows from a finite universe.

Can we agree that science does not affirm the existence of t=0?

I can agree that science can make no claims when the age of the universe was less than 1 Planck time.

Most of them. You, for example

If you're only referring to myself, I do not count as most apologists.

In order for this statement to be true, you have to assume the non-existence of any natural explanation, even an explanation we are unaware of.

If there's a current naturalistic explanation, I'm willing to entertain it.

And if you are assuming there exists no natural explanation we are unaware of, well, then you are assuming science has a complete understanding of how the natural world works.

This goes back to what Divine Insight was saying. Sure, science might have an explanation in the future. But, we cannot appeal to the future and say, "Well, science one day will have an explanation for it." or "One day science will find evidence for aliens."

I'm not saying science has a complete understanding of the natural world. Far from it, I believe science only has a limited understanding of the natural world. Many more things will be discovered by science in the future. But, we don't know exactly what those things will be at the present time. We don't even know if science will ever be able to many questions that we currently have. I'm not even saying we should stop scientific pursuits. We should learn as much as we can. But, to say that science will have the answers is based on faith.

We are already discussing the merits of the cosmological principle, which if true would have the metric expansion of space as the best explanation for our observations.

If the cosmological principle is true, sure, metric expansion of space is probably the only way to explain things. But, there are some things I find problematic with the metric expansion of space. What is causing it? Is space uniformly expanding at every single point in the entire universe at the exact same rate? If so, what can account for that?

You are free to argue the merits of the visible universe comprising most of the complete universe.

If there is no metric expansion of space and the universe is approximately 15 billion years old, the radius of the universe cannot be more than 15 billion light years.

We do have measuring techniques and have done quite a lot of measuring in a variety of distances and directions, and through all of it I've never even heard of a density pattern that occurs with respect to Earth, so I'm pretty sure none exists.

Yes, this could be a test of my model. If my model holds that the universe is heterogeneous, then density would be a function of distance and not of direction.

Although... as long as you are playing the hyper-skeptic

Well, the main thing I'm a skeptic of is the mediocrity principle. Of course, dismissing that leads to all sorts of implications.

Any and all "evidence" for God would be just as good as evidence for aliens.

I don't know what you mean by this. You mean aliens can also account for the origin of the universe?

Wasn't really thinking about the origin of the universe... but sure, why not?

Doesn't make any sense to me. Do you want to explain how aliens can account for the origin of the universe?