A Trillion Worlds • Hacker News Board

Re: A Trillion Worlds

#31

Post by peter303 » Fri, Jul 20, 2018, 8:50 PM UTC

kingbirdy wrote: post #25

jerf wrote: post #15

So, this is actually a big deal, in the "centuries-long arc of science" sense. For hundreds of years, science has operated under the Copernican Principle [1], which in a nutshell is that there is nothing particular special/unique about us. Our position on the planet is not special. Our planet is not special. Our solar system is not special. Our galaxy is not special, etc. It has been a scientifically-fruitful tool fo…

> It can't really go the other direction at this point What makes you say this? As I understand it, we've only detected a tiny fraction of the planets out there and it could be that there are plenty of systems out there similar to ours, we're just not capable of seeing them yet. Is there some reason to believe we're unlikely to ever see another system like ours, other than the fact that we haven't yet?

3807 confirmedplanets in todays catalog. You can do prettygood statistics with these.

Re: A Trillion Worlds

#32

Post by Rebelgecko » Fri, Jul 20, 2018, 9:35 PM UTC

peter303 wrote: post #31

kingbirdy wrote: post #25

Earlier quoted context omitted.

> It can't really go the other direction at this point What makes you say this? As I understand it, we've only detected a tiny fraction of the planets out there and it could be that there are plenty of systems out there similar to ours, we're just not capable of seeing them yet. Is there some reason to believe we're unlikely to ever see another system like ours, other than the fact that we haven't yet?

3807 confirmedplanets in todays catalog. You can do prettygood statistics with these.

How useful is that though? They're not a random sampling of planets in the universe--the planets that are easiest to find are very different from our own. Most of those planets are found using methods that work best on huge planets orbiting very close to small stars.

Re: A Trillion Worlds

#33

Post by labster » Fri, Jul 20, 2018, 9:43 PM UTC

Rebelgecko wrote: post #32

peter303 wrote: post #31

Earlier quoted context omitted.

3807 confirmedplanets in todays catalog. You can do prettygood statistics with these.

How useful is that though? They're not a random sampling of planets in the universe--the planets that are easiest to find are very different from our own. Most of those planets are found using methods that work best on huge planets orbiting very close to small stars.

I doubt we've even found all of the planets in our own solar system, so our data on planets is really pretty bad for statistics. Fortunately, the James Webb Space Telescope will be finished eventually[0].

[0]: https://www.xkcd.com/2014/

Re: A Trillion Worlds

#34

Post by cpeterso » Fri, Jul 20, 2018, 9:57 PM UTC

If you are interested in exoplanets, I recommend Adam Frank's book "Light of the Stars: Alien Worlds and the Fate of the Earth". He discusses the history of the Fermi Paradox, the Drake Equation, and how what we know about exoplanets can inform us about Earth's history and future.

https://smile.amazon.com/dp/0393609014

Re: A Trillion Worlds

#35

Post by btilly » Fri, Jul 20, 2018, 11:01 PM UTC

jerf wrote: post #30

baq wrote: post #18

Earlier quoted context omitted.

is 0.1% of a trillion special or not? :)

For you, that is a personal decision about the nature of "special". But I feel confident in saying, having watched the debate about the Great Questions for a couple of decades and seen at least the last ~150 years of it, and seen how firmly the default science position has entrenched itself on the hill that the Earth is completely not special [1], it's enough to falsify that position. And that's a big deal on its own…

That isn't quite right.

The default assumption is that we are normal in all ways except what is required by the anthropic principle.

The converse of that is that as we find ways in which we are special, we should immediately start thinking about why those things are necessary for us to be here. The classic example is that a large moon is necessary to keep our axial tilt from random flipping us too far every few tens of millions of years. Another good example is that Jupiter has played "comet sweeper", seriously reducing how many extinction level collisions we suffer.

This new research just underscores the fact that these characteristics truly are essential for advanced life, and are rarer than we knew.

Re: A Trillion Worlds

#36

Post by ta1234567890 » Sat, Jul 21, 2018, 3:53 AM UTC

jerf wrote: post #29

dforrestwilson wrote: post #27

Earlier quoted context omitted.

I am always skeptical of these vast sweeping assumptions about a Universe which we have not even started to seriously explore. Based on the best available scientific tools at the time, we once thought that the solar system rotated around the earth. Based on the best scientific tools available today, we believe that our solar system and planet is extremely unique. I think we don’t know nearly enough to say with any re…

The sibling comment to yours is correct in its logic in inferring what I meant. It is true that we are ignorant of many things. It is not true that our ignorance is infinitely unbounded, and it is a denial of science and rationality, not an affirmation of it, to believe such. We have gathered enough data that we already know that our solar system is not perfectly pedestrian, and no amount of additional data short of…

> It is not true that our ignorance is infinitely unbounded

Well, if you define our ignorance as information we don't yet have. Then if the Universe is infinite, it means our ignorance is unbounded.

In fact, if any type of infinity exists, then it means in general our ignorance is unbounded, because we will never be able to have full knowledge of that infinity.

For example, you can make as many assumptions as you want about the properties of the rational numbers in between two other numbers, but unless you are able to somehow "know" all of those numbers, then your ignorance about them is in part bounded by their quantity, and if it there's an infinite amount of them, your ignorance about them will be unbounded.

Re: A Trillion Worlds

#37

Post by credit_guy » Sat, Jul 21, 2018, 12:37 PM UTC

jerf wrote: post #15

So, this is actually a big deal, in the "centuries-long arc of science" sense. For hundreds of years, science has operated under the Copernican Principle [1], which in a nutshell is that there is nothing particular special/unique about us. Our position on the planet is not special. Our planet is not special. Our solar system is not special. Our galaxy is not special, etc. It has been a scientifically-fruitful tool fo…

The way I read this article, it rather reinforces the Copernican principle.

There are 3 facts in the article.

1. Planets in other systems tend to orbit faster, in a matter of weeks rather than years; therefore our system is special. Fine, this observation would go against the Copernican principle, but my guess is it's more likely to be an observation bias. Namely, if you have many transitions, before doing any math, you can't tell if it's one or several planets. If you have 10 planets, and you wrongly assume it's one, you get an perceived orbital speed that is 10 times higher (oversimplifying here a bit). If you do the math, and are able to tell apart some of the transitions, you may still think you only have 3 planets instead of 10. Identifying if transitions belong to the same planet is likely to have few false negatives but many false positives. We can follow this space, and see if future analyses confirm the current findings, or confirm my hunch.

2. Distribution of densities. Here the article mentions that for a given radius the density can vary by a factor of 10, but otherwise there is nothing special about the Earth. I would call this a plus for the Copernican principle

3. The distribution of planet sizes. This one is double peaked, and the size of the Earth is part of one peak, not of the valley. This is a big plus for the Copernican principle.

Re: A Trillion Worlds

#38

Post by jvanderbot » Sat, Jul 21, 2018, 9:13 PM UTC

credit_guy wrote: post #37

jerf wrote: post #15

So, this is actually a big deal, in the "centuries-long arc of science" sense. For hundreds of years, science has operated under the Copernican Principle [1], which in a nutshell is that there is nothing particular special/unique about us. Our position on the planet is not special. Our planet is not special. Our solar system is not special. Our galaxy is not special, etc. It has been a scientifically-fruitful tool fo…

The way I read this article, it rather reinforces the Copernican principle. There are 3 facts in the article. 1. Planets in other systems tend to orbit faster, in a matter of weeks rather than years; therefore our system is special. Fine, this observation would go against the Copernican principle, but my guess is it's more likely to be an observation bias. Namely, if you have many transitions, before doing any math,…

On 1. 10 planets equally radially spaced dont cause a wobble like 1 going fast. Also 10 planets equally spaced are quickly not equally spaced due to differing orbit vel. 10 isn't the problem, assuming aliasing is the problem.