Podcast Episode 166: Stellar Evolution, Age of the Universe, and Young-Earth Creationism

Star evolution,
Age of the universe, and
Creationism.

Young-Earth Creationism strikes again and this time misuses error bars to argue that GodDidIt. The episode covers a science paper that discussed the age of a very old star which was derived to be a bit older than the universe. But, add in the appropriate error bars, and potentially a correction to its color, and there’s absolutely no issue whatsoever. But, try telling that to a creationist with an agenda. There’s only a very brief singular additional segment in this episode.

The dazzling stars in Messier 15 look fresh and new in this image from the NASA/Hubble Space Telescope, but they are actually all roughly 13 billion years old, making them some of the most ancient objects in the Universe. Unlike another recent Hubble Picture of the Week, which featured the unusually sparse cluster Palomar 1, Messier 15 is rich and bright despite its age. Messier 15 is a globular cluster — a spherical conglomeration of old stars that formed together from the same cloud of gas, found in the outer reaches of the Milky Way in a region known as the halo and orbiting the Galactic Centre. This globular lies about 35 000 light-years from the Earth, in the constellation of Pegasus (The Flying Horse). Messier 15 is one of the densest globulars known, with the vast majority of the cluster’s mass concentrated in the core. Astronomers think that particularly dense globulars, like this one, underwent a process called core collapse, in which gravitational interactions between stars led to many members of the cluster migrating towards the centre. Messier 15 is also the first globular cluster known to harbour a planetary nebula, and it is still one of only four globulars known to do so. The planetary nebula, called Pease 1, can be seen in this image as a small blue blob to the lower left of the globular’s core. This picture was put together from images taken with the Wide Field Channel of Hubble’s Advanced Camera for Surveys. Images through yellow/orange (F606W, coloured blue) and near-infrared (F814W, coloured red) filters were combined. The total exposure times were 535 s and 615 s respectively and the field of view is 3.4 arcminutes across.

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Are We on the Verge of Discovering an Earth-Like Exoplanet?

I announced awhile ago that I was on episode 347 of the Canadian, “The Reality Check” poscast where I talked about exoplanets and some hype — deserved or otherwise — about almost but never quite yet discovering Earth-sized exoplanets.

While they post a lot of links and other things on their website, they don’t post transcripts of what we actually talk about. Since I spent a solid many minutes writing and editing my segment’s text, I thought I’d post it here:

There’s lots of ways to talk about exoplanets, but I’m going to take the traditional approach and start with a very broad but brief overview of how we have found the few-thousand known extra-solar planets, or “exoplanets” for short. There are five main ways.

The most obvious is the most difficult: Direct Imaging. This is where you take your telescope and would look at a star and see the planet around it. This is almost impossible with current technology, and we have less than 20 exoplanets found this way. It’s so hard because the star is so bright relative to the planet and because most star systems are so far away. And obviously, if the planet is larger and farther away from the star, it’ll be easier to see.

The second main method has also only produced about 20 planets so far: Gravitational Microlensing. Einstein showed that large masses bend light, and we can see this in space when an object that’s far away passes behind a massive object that’s a lot closer. The light from the background object gets distorted and magnified, much like a lens … a lens caused by gravity. If the foreground object happens to be a star, and that star has a planet, then that planet can make a detectable contribution to the lensing, not only in amount, but in the exact shape of the lensing effect.

The earliest actual successful method was a special form of what’s called the Timing Method, specifically in this case, pulsar timing. Pulsars are incredibly dense stars called neutron stars, and we get a blast of radio waves every time one of its poles sweeps in the direction of Earth. These are so regular that any tiny perturbation can be detected and attributed to something weird, like a tiny planet tugging on it and so changing that regular spinning signal.

This is the same concept as the highly successful method that found the most exoplanets until a few years ago: Radial Velocity. The idea is that we normally think of a planet, like Earth, orbiting the sun. But it doesn’t really. It *and* the sun orbit a mutual gravitational point called the “barycenter” that is between the two. For Earth and the sun, that point is VERY close to the sun’s center, but it’s not quite in the center. That means that over the course of a year, as Earth goes around that point, the sun will, too (on the opposite side of that point). So, it will wobble very very slightly as it orbits the barycenter.

We can’t possibly observe this tiny tiny motion of other stars. BUT, we can use the light that star emits to do it by using the Doppler shift. That’s the phenomenon where if something is moving towards you, the waves it emits become compressed, and if it’s moving away from you, the waves get stretched out. The common example is a train whistle going from high to low pitch, but in astronomy, this is where the light is shifted to blue and then to red.

So, if the planet around another star is at its closest point to us, the star emits light and we see it all normal. As the planet starts to move away from us, the star starts to move very slightly toward Earth, and so its light will be very slightly blue-shifted. Then, the planet gets to its farthest point, and starts to move towards Earth, which means the star starts to move away, and we see its light red-shifted. This is an incredibly tiny effect, and the smaller the planet, the smaller the shift in the light. Or the pulsar timing change.

There was a lot of progress throughout the late 1990s and early 2000s in very high-resolution spectroscopy in order to get better and better at observing smaller and smaller planets. The easiest ones to observe are the largest because they make the biggest shift in the star’s light, and ones that are closest to their star are easier because you don’t have to observe as long. To observe a planet that has a 10-day orbit, you just have to observe that star for about a month from Earth to get decent statistics.

That’s why all the exoplanets discovered early on were what are called “Hot Jupiters,” since they were very large and very close to their stars.

The final method is the Transit Method. If a fly passes in front of a bright light, you can see a slight decrease in the light. If a bird passes in front of a light, you’ll see a larger decrease in the light. Same thing here: A planet passes in front of the star and temporarily blocks part of the light from the star that we would see at Earth. The big issue with this method is that you have to have the fortuitous geometry alignment where the planet’s orbit is just right so that it passes in front of its star as seen from Earth. The first one wasn’t detected until 1999, but a decade later, the dedicated spacecraft COROT and then Kepler were launched to look for these, monitoring the same fields of the sky, tens of thousands of stars, moment after moment, looking for those brief transits. In 2014, Kepler released over 800 planets discovered with this method, more than doubling the total number known, and that was on top of its other releases and, to-date, it’s found over 1000.

The transit method, despite the issue of geometry, is probably the best initial method. If you have the planet going in front of its star, then you know its alignment and you can follow-up with the radial velocity method and get the mass. Otherwise, the radial velocity method can only give you a minimum mass because you don’t know how the system is oriented, you only know that radial component of velocity, hence its name.

With the transit method, you can see how much light is blocked by the planet. Knowing the star’s type, you can get a pretty good estimate for the star’s size, and knowing how much light is blocked means you can get the cross-sectional area of the planet and hence its diameter. For example, Jupiter would block 1% of the sun’s light, and since area is the square of length, that means Jupiter is about 10% the sun’s diameter. Since the sun is a type G V star, we have a good model for its radius, though of course we know its radius very well because we’re in orbit of it. But that means not only can we get mass, but we can get size and density.

The transit method also lets us see if there’s a large atmosphere. If the light from the star instantly blinks down to the level when the planet passes in front of it, then any atmosphere really thin or nonexistent. If there’s a gradual decrease, then it’s extended. If its extended, we can follow-up with something like the Hubble Space Telescope and actually figure out what that atmosphere is made of by looking at what colors of light from the star are absorbed as it passes through the planet’s atmosphere.

And as with the radial velocity and timing methods, we know how long it takes to go around its parent star, and along with the star’s mass from what kind of star it is, we can get the distance of the planet from the star.

Okay, so much for a brief overview. But for me, I’ve left out a lot.

Moving on, it should be somewhat apparent that the bigger the planet, and the closer to its star, the easier it is to observe with pretty much ANY of these techniques, except direct imaging or microlensing where you want a big planet that’s far from its star. Big means big effect. Fast orbit means you don’t have to observe it for very long to show that it’s a regular, repeating signal best explained by a planet.

So, the question is then, can we detect an Earth-sized planet, and can we detect an Earth-like orbit? These are really two different questions and they depend on the technique you’re using. If we want to focus on a the two main methods – radial velocity and transit – then the unsatisfying answer to the second is that we do finally have good enough technology, it is just a matter of finding it. With the 2014 Kepler data release, there were over 100 exoplanets that are less than 1.25 Earth’s size. With the 2015 release, there are a total of 5 planets smaller than Earth or Venus, but they orbit their 11.2-billion-year-old star in just 3.6 to 9.7 days.

Even if we have observations for more than a year or two, for something as small as Earth, the level of signal relative to noise in the experiment is still pretty small, and you want a big signal relative to the noise. It’s best to build up multiple years’ worth of data to average out the noise to be able to really say that we have an Earth-like planet. For something like Jupiter, which orbits our sun in about 12 years, we’d need to observe at least two transits, meaning we’re just now approaching the time when we would have a long enough baseline of data with some ground-based surveys, but that’s also assuming we catch that planet for the few hours or days when it goes in front of its star versus the years and years that it doesn’t, and that we do this repeatedly and don’t chalk it up to sunspots.

This is why we really need long-term, dedicated surveys to just stare at the same place in space, constantly, measuring the light output of these stars to see if we can detect any sort of dimming, that’s repeated, from a likely planet.

But, even if we find an Earth-like planet in terms of mass and diameter and location in its solar system, that’s not enough to say it’s Earth-like in terms of atmosphere and surface gravity and overall long-term habitability. It’s just a first step. A first step we have yet to truly reach, but one that is reasonably within our grasp at this point.

But it’s from the existing planets we know of that we get some of the hype that hits the headlines every few months, like “astronomers estimate billions of Earth-like planets exist in our galaxy alone.” I’m not going to say that’s fantasy, but it’s loosely informed speculation based on extrapolating from a few thousand examples we now have from a very, VERY young field of astronomy.

Or, we’ll get articles where the first sentence says, “Astronomers have discovered two new alien worlds a bit larger than Earth circling a nearby star.” It’s in the next paragraph that we learn that “a bit larger than Earth” means 6.4 and 7.9 times our mass, and they orbit their star in just a few days.

So as always, this is a case where, when we see headlines, we need to be skeptical, NOT susceptible to the hype, and read deeper. But that said, it is entirely possible that any day now we will find an exoplanet that is at least like Earth in mass, size, and distance from its host star.

Why Do Young-Earth Creationists Even Try to Pretend at Science?

There are a few main young-Earth (Christian) creationism organizations in the world that rise to the top in terms of reach and output and attempt to use science to justify their beliefs. Among those I would name three: Answers in Genesis (US-based, headed by Ken Ham), Institute for Creation Research (US-based, founded by Duane Gish), and Australia-based Creation Ministries International (which I think was also founded by Ken Ham, but AiG and CMI severed ties several years ago, fairly acrimoniously).

Over the past eight years, I have dealt with articles by all three, and other. In fact, my early posts mostly consisted of ripping through YEC claims. That’s mostly fallen by the wayside as posts have (regrettably) decreased over the years as I became more and more busy with work, but occasionally I’ll still see something that I want to comment on.

But more on that momentarily.

What these Big Three do, among other things, is attempt to do science and/or report on science. They’ve realized that as each new scientific discovery has borne out that contradicts their sacred tome, more and more people will leave their strict, literal interpretation of their religious writings.

Ergo, they have to try to show that science somehow supports something that they’ve said and believe.

I’ve also done numerous posts on this blog about the scientific process and why – to be a good scientist – you must also be a skeptic: You must find a way to remove your own bias(es) from the experiment. You must be able to objectively look at the data and also try to disprove what you want to think is the case in order to see if the data are ambiguous or really do exclusively support the conclusion. You have to think of all the other interpretations and gather observational evidence that those explanations are not valid. The process is not infallible, but it’s a heck of a lot better than a dogmatic approach.

Which, despite all the façade, is what creation “science” really is. And, surprisingly, I couldn’t’ve said it better myself than what Creation Ministries International wrote a few days ago in trying to answer a reader’s question about when stars were formed:

“what you propose is clearly ‘science’-driven not text-driven”

Blasted “science!” Always interfering with the Bible! (or at least their reading of it)

But, realizing it or not, this clearly demonstrates that what YECs do is not science: They start with their conclusion and will modify or massage or tweak or somehow shove the data into that hole to make it come out right. Or, simply deny that it exists (such as Kent Hovind denying there are reversals in Earth’s magnetic field, or almost all YECs denying accuracy of radiometric dating). This handy flowchart I made several years ago sums it up nicely:

Flow Chart Showing Faith-Based “Science”

Podcast Episode 27: Stellar Scams

Day late, 20 hrs of work left to do before I leave for the airport in 10 hours … sorry. This episode is about buying star names and land on other planets.

This week, I’m introducing a new, alternative segment to the puzzler. My tentative name for it is “Fact or Fake.” This totally original idea that is not ripped off from any other popular skeptical podcasts is where I will present you with two to four items, based loosely around the topic in the main segment, and you need to figure out which is or are fact, and which is or are fake.

The reason for this segment shift is that the puzzlers are sometimes really really hard to come up with, hence why I’ve been soliciting ideas for the past few episodes. This doesn’t mean that the Puzzler is retired — if I can come up with a puzzler that’s good for the topic of the episode, then I’ll use it. If I can’t, then I’ll do this new segment. That said, the NEXT episode is going to be an overview of the asteroid belt, and whether it was ever a planet. If you can think of a good puzzler for that, please send it in.

This is my first attempt at this thing, so let me know what you think.

God Said Stars Are Made from Water?

This is a quick post that is kinda another “WTF?” post from something that the young-Earth creationist (YEC) Institute for Creation Research’s (ICR) “science” writer Brian Thomas put out in his article, “What Causes a Galaxy’s Magnetism?”

About the first two-thirds of the article is basically parroting a press release about a new map of the Galaxy’s magnetic field. The jist of the press release is that a team of astronomers has mapped our galaxy’s magnetic field to higher precision and accuracy than had been done previously with an eye towards studying extragalactic magnetic fields: you need to know what’s in the way before you can figure out what’s going on with a far-off object. It can also act, over time, on slightly magnetized dust and gas within the galaxy.

But – gasp! – we don’t know why the Galaxy has a magnetic field to begin with! As the ICR article states, “Secular astronomers are no closer to understanding what could cause galactic magnetic fields than they were when they first detected the fields over a century ago.” (That’s the first sentence of the article.) You kinda know what’s coming next … a God of the Gaps argument.

From what I can tell – and this is WAY outside of my field so if any astronomer who knows more about this reads this post, please post in the Comments – the statement is true that we don’t really know what caused the Galaxy’s magnetic field to form in the first place. But, a very recent article has an idea that it may have formed from a background field “seed” that became stronger as the Galaxy formed. So it’s not like we’re totally ign’ant, there are ideas out there.

But no, apparently that’s not good enough. Creationists have to figure it out from the Bible, and …

“In 2008, physicist D. Russell Humphreys proposed a Bible-centered model for the origin of magnetic fields that is consistent with the overall strength of the spiral Milky Way’s magnetic field. If God formed the stars and galaxies during the fourth day of creation using water that He had created earlier, and if those water molecules were all originally aligned, their tiny magnetic fields would have combined to form a galactic magnetic field that has decayed to something that looks like today’s observed field strength.”

Yup, that’s right. The premise of this creationist proposal is that stars are made from water. I really don’t think anything else needs to be said at this point.

The Many Stars of the Heavens … Are Young?

Introduction

In my unofficial rivalry with a high school student, it looks like I’m finally getting a post up before him about the latest from Brian Thomas and the Institute for Creation Research’s “Daily Science Updates.” Though it’s really an unfair challenge because he’s in a land Down Under and wakes up about the same time that these suckers go up on the ICR’s website. I’m supposed to be in bed.

This post today is about the IRC’s post, “New Study Can’t Explain Blue Stragglers’ Youth.”

About Stars

Stars are important. Perhaps that much should be obvious to everyone. In the current epoch of the universe, stars are what provide energy to allow some minor things like, say, life to exist. Stars are formed generally with a set amount of gases, and the vast majority of this gas is hydrogen. In the core of stars – roughly the inner 10% in a sun-like star – temperatures and pressures are high enough for fusion to occur which is what provides energy.

It also prevents the stars from collapsing. Stars are a balancing between outward pressure from heat and energy versus the collapsing force of gravity. Gravity compresses the gas until fusion begins and counters it. In small stars, there is less force of gravity, and so the pressures and temperatures are lower and fusion goes on more slowly. In large stars, there is a larger force from gravity, the pressures and temperatures are much higher, and fusion goes on at a much faster rate and over a larger portion of the star in order to prevent collapse.

This means that even though smaller stars – say, red dwarfs – are significantly lighter than the sun, they will be able to continue to fuse hydrogen for roughly 10 trillion years as opposed to the sun which has an estimated lifetime of 10 billion years.

Contrast that with the gigantic stars – blue supergiants – which are generally up to about 50 times the mass of the sun, and these will go through their nuclear fuel in roughly 10 million years. In each of these (red dwarfs, yellow dwarfs like the sun, blue supergiants), we’re dealing with a factor of one thousand difference in expected lifetime because of the different pace of fusion.

Blue Stragglers

Surrounding our galaxy, there are roughly 175 known groups of stars called globular clusters. These are tight groupings of many hundreds of thousands to millions of stars that generally all formed at once (astronomically speaking) and lack any interstellar material from which to form new stars. There are different ideas for how these originated – some think they were just clouds of gas that collapsed into dense clusters of stars, similar to open clusters, while others think they may be the cores of small dwarf galaxies that were consumed by our galaxy.

What’s known is that effectively every globular cluster surrounding our galaxy is very old, on the order of 10 billion years. In fact, before we had good models of stellar evolution, there was a disconnect in cosmology where we thought globular clusters were older than the universe (obviously that could not be true). It’s important to note in a post about this particular subject that these have since been reconciled both by better estimates for the universe’s age and better stellar models.

The point is that globulars around our galaxy are old (many around Andromeda are young, but this post is not about them). The problem is that most globular clusters contain a few blue supergiant stars known as “blue stragglers.” These are, well, blue supergiant stars. Given what I said above, these should not exist in an old star cluster because they should have exploded 10 billion minus 10 million years ago.

The same can be said about some open clusters in our galaxy, except that open clusters are usually young and they contain fewer members. Open clusters usually form within the plane of the galaxy, and over the course of a few hundred thousand to hundred million years, the member stars disperse due to interactions with other stars. So, most are young and most happily contain blue supergiant stars that are no problem for stellar evolution models.

There are a few exceptions, and one of them is discussed in the article that’s the subject of this post.

NGC 188 is well above the plane of the galaxy, so it has managed to stay together for about 7 billion years. All the members formed at about the same time, except that it contains some of those blue stragglers. So again, we have a question that needs answering: How do you get stars that are supposed to have lifetimes at 10 million years in a cluster that’s 7 billion years old?

Enter Brian Thomas and the Young-Earth Creationists to the Rescue!

Mr. Thomas’ article is responding to a recent Nature paper entitled, “A mass transfer origin for blue stragglers in NGC 188 as revealed by half-solar-mass companions.” With the wonders of the internet, you can read the paper yourself for free here (it’s short, but it’s pretty technical).

Now, to start off with, when I was an undergraduate just a very very few short years ago, because I’m not old, we were taught that the likely explanation for blue stragglers was that they were a second generation of stars within open clusters. These days, it appears as though the most promising explanations are either a collision between two stars that produces a massive enough result to make a blue supergiant, and/or a star in a close binary system that siphons off material from a companion to give it enough mass to turn into a blue supergiant.

This paper, in particular, that Thomas references was looking at the latter explanation. Through their observations, they have statistically ruled out the merger as the likely explanation and settle on mass transfer as the more likely of the two. They end their paper by saying mergers of triplets may happen, though. Remember: Clusters are dense and so binary and trinary systems are not uncommon.

The problem with this, according to Thomas, is:

“Nothing explains the many blue stragglers that are not binary stars and yet exist near and far throughout the universe. Could they have received recent “youthfulness” through collisions with other stars?”

I’m not actually sure where Thomas is coming from here. By definition, blue stragglers kinda need to be a member of a cluster of stars because otherwise they wouldn’t be blue stragglers. The reason we know they “shouldn’t” be so young is that we need a cluster that all formed at the same time from which to say, “Oh, every star in here formed at the same time, the bulk age is 5 billion years, therefore giant massive blue stars are out of place.” Perhaps Peter can provide context for this.

Moving forward to the next-to-last paragraph of the ICR article:

“So, isolated blue stars could not have received their young looks from a binary system, since by definition they have no binary from which to siphon fuel. They probably didn’t receive their youthful appearance from collisions, either, according to these results. And though the binary blue stragglers may have siphoned fuel from nearby partners, the idea that 12 of 16 only did so recently—after an imagined 7-billion-year wait—defies reasonable odds.”

At some point in skepticism and debunking, we simply have to ask, “Show your work/math.” Brian, show your math here. How did you calculate what are “reasonable odds?” We’re talking about a cluster with over 10,000 stars in a tightly confined space. Brian is presenting a specific, statistical claim. He needs to back it up with data before it’s even worth going into further.

It’s like me saying it’s mathematically impossible for 100 billion trees to exist on this planet. Okay, fine, but before anyone should accept that or take my word for it, they should demand to see evidence.

But, at least in that article (I see no link to “further math” nor “supplemental material”), he does not. Rather, the next sentence is “goddidit.” Err, sorry, it’s: “Thus, the best explanation is still the most straightforward one—blue straggler stars look young because they are young.” Yeah — what I said: “Goddidit.”

Edited to Add: Solstation.com has a nice illustration showing the two different models:

Missing the Forrest for the Tree

I find it interesting when young-Earth creationists use star ages to argue for a creation only a few thousand years ago. The whole “problem” with blue stragglers is that they are in a system that is otherwise dated to be several billion years old. And yet creationists don’t address that big, glaring contradiction to their “model.” Or in discussing supernovae and why there appear to be “too few” of them for the age of the galaxy (let alone universe), they miss the entire fact that supernovae occur at the end of a massive star’s death which takes at least 10 million (not thousand) years to happen.

Or that there exist neutron stars and black holes, which are the remnants from these explosions which would have again taken at least 10 million years to happen.

Or that there exist white dwarfs, which are the remnants from a sun-like star at the end of its life, and yet that takes several billion years to form.

At that point, for creationists, they must simply revert to God as Loki, the Norse trickster god. God made everything with the appearance of age to trick us. That’s not the kind of god that I think deserves to be worshiped. Nor, actually, do I quite understand why an omnipotent being has such a personality insecurity and low self-esteem to need to be worshiped. But I digress from astronomy here.

Final Thoughts

Why and how blue stragglers exist is an open question in modern astrophysics. It’s an interesting question, and it’s one that may not have a single answer. The latest paper seems to indicate that at least in this cluster, binary collisions are not the likely formation mechanism. It may be elsewhere. It could be trinary. It could be mass siphoning. We don’t know. But never should we revert to and replace “we don’t know” with “goddidit.” That simply stops science in its tracks and leaves willful ignorance in its wake.