We Might Be Alone in the Universe

[doubtingthomas]

You are making enormous assumptions that intelligent aliens will think like you do.

I am not assuming that at all, did you not read what I said?

I said, "It's doubtful that all alien civilizations would behave the same way".

Some will think like me, but not all of them.

You can come up with many reasons why the vast majority of alien civilizations don't expand, but those reasons won't apply to all civilizations. We should expect at least one civilization to be the exception.

All you are doing is layer upon layer upon layer of absolute speculation based on no evidence whatsoever

Isn't PG also speculating?

[doubtingthomas]

Please don't make specific claims about a study without quoting from it. What leads you to conclude that?

A star's rotation rate can be used to estimate a star's age. How do you calculate the age of non-periodic stars? Does the second study (of non-periodic stars) take age into account?

[doubtingthomas]

Things are still allowed to be rare, like supernovas and quasars—just not unique.

Yes, so shouldn't we expect rare civilizations? If there are thousands or millions of advanced civilizations in galaxy, shouldn't a very tiny minority of civilizations expand?

[doubtingthomas]

And 87% of the stars in the total sample were as relatively quiet as the sun.

Let me ask, you really have to answer this one.

Are the authors concluding that the Sun is quieter than most Sun-like stars (with similar rotation periods) because the Sun happens to be a non-periodic star? Do you realize there are two studies in that paper?

Please.

[Res Ipsa]

All I'm saying is that, given the large number of possible places where life could form and the fact that intelligent life has formed once, the odds are virtually certain that intelligent life has formed or will form again somewhere in the universe.

Define "universe". Are you talking about the observable universe?

Observable. I think that's more consistent than your use of the term "alone."

I thought you changed your mind on this one. Just because something happens once doesn't mean it will happen again in the observable universe. It's best to be agnostic.

It's nuance that depends on what question is being asked. If you ask me, do you know whether there is other intelligent life in the universe, the answer is "no." You'd get the same answer if you asked the other way. But that doesn't mean I don't have an opinion or belief. If you ask me, what is the likelihood that there has been, is, or will be other intelligent life in the universe, the answer is "I think it's a virtual certainty." I don't see any contradiction between the two. It's like being an agnostic atheist -- I don't purport to know that there is no God, but I see no reason to believe in one. That's why Professor Kipping can say it's best to be agnostic and to express his "bet" as to the existence of other life and intelligent life in the universe.

I'm not asserting that the fact that something happened once means it necessarily must happen again. My opinion is based on what we know, what we don't know, and that, in the absence of evidence that earth is somehow unique in terms of possessing the necessary conditions for life to form, we should not assume that it is unique. That, combined with the sheer number of planets, drives my opinion to virtual certainty.

But it's how I would bet, not what I claim to know.

Since then, I think we've been exactly the same place. I understand your argument as:

1. The solar system is unique, therefore
2. Intelligent live in the universe is rare.

Yes, somewhat. Let me change it a bit.

1. If the solar system is a "cosmic oddity", then
2. Intelligent life is probably rare. Not impossible, but rare.

3. If the probability of life is 10^-100, then
4. Alien life is virtually impossible in the observable universe.

Does that make sense?

The change in number one kind of begs the question. What does "cosmic oddity" mean? Try putting it in percentage terms. The same with "rare." Part of the problem is that you and I and Professor Kipping are all using the word "rare," but that doesn't mean that we are defining the word the same way.

The addition of 3. and 4. helps quite a bit, as it clarifies that the "virtually impossible" part is a different argument.

As stated, I agree with 3. and 4. My response is that the assumption in 3. means that it is virtually impossible for ANY life to exist in the observable universe, including us. Because we exist, making the assumption in 3 is absurd and we shouldn't make absurd assumptions. Given that we don't know anything about the necessary conditions, etc. for life, there is simply no reasoned basis for assuming a probability at this point in time.

My view of Sean Carroll is that he is a smart guy who would not seriously advance an obviously absurd claim. Given that the number was contained in a single tweet at the thick headed Mr. Musk, I don't see any reason to interpret it as a number having a basis in some kind of evidence. It was likely hyperbole or 100 was just a big, round number he threw in. If you read the tweet he was responding to, it's clear that he was communicating that Musk was overlooking how rare intelligent life in the universe could be.

The alternative, to interpret the tweet as if the figure was the conclusion of a published study, is to assert that Caroll is a moron. Which he is not.

I think that 90% of our disagreement is about the soundness of your arguments. It is perfectly possible to make obviously invalid arguments in favor of a correct conclusion. I don't see your point no. 2 as contradicting my own position. The devil is in the details.

[Res Ipsa]

All of that could be true.

However, let's assume there are one thousand advanced civilizations in the galaxy. Shouldn't we expect at least one civilization to be the exception? It's doubtful that all alien civilizations would behave the same.



Probably, but the authors don't know for sure if the Sun would be a non-periodic star. It's just their best guess.



One of the researchers said, "We were very surprised that most of the Sun-like stars are so much more active than the Sun". Why would the researchers be surprised if the Sun is just a non-periodic star?



Not me, but Kipping probably does know more than all of them. He interpreted the data.

Anyways, the second study doesn't take into account one important thing: The average age of non-periodic stars. If most non-periodic stars are older than the Sun, then the data makes a lot of sense.

I'm trying to follow the arguments here without going into all of the details in the references - probably not a good idea, right?

To kind of test my understanding of what's going on, I'll attempt to address just your first point above:

However, let's assume there are one thousand advanced civilizations in the galaxy. Shouldn't we expect at least one civilization to be the exception? It's doubtful that all alien civilizations would behave the same.

By "the exception" I assume you mean an exception to what Res said:

Maybe interstellar civilisations expand, but maybe they just don't.

My answer is: No!

Even if there were a million civilizations, we have no reason whatsoever to expect that one of them would be an exception to an arbitrary "for example" rule of this sort. It's perfectly possible. It's also possible that every single one is an exception. But we have no reasonable expectation for either one or all to be exceptions. We simply do not know, and cannot even begin to calculate the probability.

Am I totally out to lunch here? Could be. I'd be grateful if someone would tell me, and - preferably - explain to me why.

This piece of the argument isn't tied to the studies we've been discussing. "We simply do not know, and cannot even begin to calculate the probability" is exactly correct. We have no basis on which to assume how another intelligent civilization would behave.

[Res Ipsa]

I think the Copernican principle has to try to say that there are aliens out there somewhere, but I don't see how it has to say that they are common. Things are still allowed to be rare, like supernovas and quasars—just not unique.

The simulation argument just seems naïve about how much resolution is needed to make a simulation indistinguishable from reality. Once you're simulating every electron, just what is the difference between that simulation and reality, anyway?

The doomsday argument seems the weirdest of all. Assuming that every process is always most likely to be about mid-way through its total duration would imply that the moment when every process should be expected to have the shortest time left in it is the moment when it has just begun, and conversely that the moment when any process should be expected to have the longest duration remaining is the moment just before the process actually ends. A rule which is supposed to be the most logical estimate should surely not be so badly wrong, so consistently.

That's the way I would apply the principle.

[Res Ipsa]

.

I corrected this reply, please read this one

All of that could be true.

However, let's assume there are one thousand advanced civilizations in the galaxy. Shouldn't we expect at least one civilization to be the exception? It's doubtful that all alien civilizations would behave the same way.



Probably, but the authors don't know for sure if the Sun would be a non-periodic star. It's just their best guess.



Not me, but Kipping probably does know more than all of them. He interpreted the data.

Anyways, the second study doesn't take into account one important thing: The average age of non-periodic stars. If most non-periodic stars are older than the Sun, then the data makes a lot of sense.

That doesn't answer my question. First, what do you mean by second study? The paper certainly doesn't demarcate separate studies. What leads you to the conclusion that the paper discusses two studies? Also, what in the paper leads you to conclude that it doesn't take into account the age of the non-periodic stars?

[Res Ipsa]

And 87% of the stars in the total sample were as relatively quiet as the sun.

Let me ask, you really have to answer this one.

Are the authors concluding that the Sun is quieter than most Sun-like stars (with similar rotation periods) because the Sun happens to be a non-periodic star? Do you realize there are two studies in that paper?

Number one, I don't see two studies in that paper. I see one study with one sample that includes two subsamples. That two subsamples were examined does not magically transform one study into two. Please quote from the paper anything that refers to two studies.

No, that is not what the authors conclude. Because they are relying on data from Kepler's data and their sample included sunlike stars that differed only in Kepler's ability to determine a rotational period, they wanted to compare the sun with the sample on an apples to apples basis -- as viewed by Kepler. Kepler would have classified the sun as a non periodic star. And the other stars classified as non-period stars displayed the same "quietness" as does the sun. Yet, when we add information that Kepler would not have provided, we know that the sun is a periodic star. It's a puzzle, and the author's properly respond by saying they can't explain it. But none of that changes the fact that the stars in the two groups were identical except for whether Kepler identified the period of rotation. So, 87% of the sample was sun like, except that their period of rotation was not defined by Kepler, and displayed the same relative "quietness" as the sun. You can't simply ignore that fact when you talk about the extent to which the sun is unusual.

[Res Ipsa]

You are making enormous assumptions that intelligent aliens will think like you do.

I am not assuming that at all, did you not read what I said?

I said, "It's doubtful that all alien civilizations would behave the same way".

Some will think like me, but not all of them.

You can come up with many reasons why the vast majority of alien civilizations don't expand, but those reasons won't apply to all civilizations. We should expect at least one civilization to be the exception.

All you are doing is layer upon layer upon layer of absolute speculation based on no evidence whatsoever

Isn't PG also speculating?

You have no reason to believe that any civilization would think like you. You have no idea what an alien civilization would even look like. That's the point. Given that we have no reason to expect that any alien civilization would expand, let alone the rate it would expand or how far it would expand, I have no obligation to invent reasons why they wouldn't. Part of making a convincing argument is recognizing what you don't know and not asserting what you don't know.

Of course PG is speculating. The difference is that he isn't pretending to be able to predict what an alien civilization is likely to do.