Starts With A Bang

Comments of the Week #107: from looking like a scientist to Earth Day lessons

Image credit: NASA / Apollo 8.

“I left Earth three times and found no other place to go. Please take care of Spaceship Earth.” -Wally Schirra

We’ve made it through another amazing week here at Starts With A Bang, and what many of you might not realize is that there was a fabulous new release thanks to the support of everyone on Patreon: a new Podcast, this time on Planet Nine!

The Universe is still delivering hordes of wonder to anyone and everyone curious about it, and that’s why last week saw us cover the following topics:

There’s lots more in the pipeline, but let’s take a look back at what you had to say for our Comments Of The Week!

Image credit: The Millenium Simulation, V. Springel et al., of the cosmic web of dark matter and the large-scale structure it forms.

From Chris Mannering on the Universe’s homogeneity: “What is the scale at which the universe is homogenous? How well can we observe that scale?”

If you look at planet-sized scales, star-sized scales or even galaxy-sized scales, the Universe is wildly inhomogeneous. But if you start looking at sizes of around ~100 Mpc on a side or more (about a few hundred million light years), the Universe starts to look pretty similar everywhere, where the biggest density differences are less than a factor of two. If you head to much larger scales, on the order of about ~1-2 Gpc or more, or roughly about 10% (on a side) of the observable Universe, the Universe starts to look homogeneous to about 1 part in a few thousand in most regions. We can observe that scale very, very well, especially with the advent of both 2dF and, more recently, the Sloan Digital Sky Survey.

Image credit: Sloan Digital Sky Survey – III / Data Release 8.

Upcoming, larger surveys from things like the LSST (from the ground) and WFIRST (from space) will go even farther, to higher resolution and with greater coverage. The largest scales of all, of about 5 Gpc (~15 billion light years on a side) will then be better probed, where the density differences between regions should be under 1-in-10,000. In summation, large-scale homogeneity is very well established, and we are striving to do even better. This is 100% consistent with the CMB and with our models of structure formation, but is also, observationally, completely independent of them.

Image credit: Breakthrough Starshot, of the laser sail concept for a “starchip” spaceship.

From PJ on the breakthrough Starshot and a different power idea: “By the time this project happens, there will be regular visits to space from the private sector & contractors.”

I don’t have anything negative to say about the lens-focusing idea, since this is plausible and, moreover, scalable in the same sense that using a large number of lasers is scalable. But the sentence I quoted above… that is really optimistic about the future of space travel over the next 20, 30 or even 50 years. We can’t even get regular visits to low-Earth orbit right, and we’ve been going to low-Earth orbit for nearly 60 years now. PJ, I hope you’re right, but I’m not certain.

Image credit: J. Cummings (foreground); NASA, ESA, SSC, CXC, and STScI (background), of Ethan Siegel in 2014.

From Chris Mannering on judging my… photographic mannerisms: “The way you look is fine but something that is curious is just that you never use your natural face. Your mouth is always wide open as the centrepiece of more or less the same facial contortion. I think you must be doing this for a reason.”

So I’m going to punt this answer over to someone much more famous than I am, and let Miley Cyrus take it away, since she’s been asked so frequently about sticking her tongue out all the time in pictures instead of smiling:

“The tongue started from, again, with me having to go on red carpets, and everyone would just tell all these girls that had so much makeup on and their hair all done in their perfect, little, pretty dress to smile and to wave. I hated when the paparazzi would tell me to blow them a kiss. It just felt so gross, and like, sexist for me to be standing there and these men to be taking my picture. So I just said forget it.”

Image credit: Hollyscoop, via

So there are a lot of valid reasons one can pose in a particular set of poses for the camera, including smiling, blowing a kiss, appearing expressionless, or — as you’ve noticed I’ve chosen — appearing kind of like a muppet, with my mouth ajar a bit. If you’re going to be seen by the world, you have every right in the world to present yourself to it according to your own choices. Personally, I hate the way I photograph in candids and in most standard smiling poses, so I found one that I like best and I stick with it.

Lots of people feel awkward in pictures, like it doesn’t represent the way they actually look (or more importantly, the way they actually see themselves), and practically everyone is sensitive about some physical feature about themselves. I don’t know why you want to figure out what my own insecurities are, but I’ll be generous enough to tell you that in general — and I do this, too — people pose for pictures in ways that reflect how they feel best about being photographed.

Dianne Feinstein and Bobak Ferdowsi (a.k.a. “NASA mohawk guy”), the activity lead for NASA’s Curiosity mission. Image credit: AP Photo/Damian Dovarganes.

From Denier on appearances and professions: “While I understand and even cheer your sentiment, it is unfortunately not the world many, if not most, live in. My scientist wife is a perfect example. She has wanted to dye her hair blue for as long as I’ve known her, but a big part of her job is testifying in court on criminal cases. Neither my wife or I have any social media footprint so as to keep her attack surface minimized. Lawyers and their investigators look for everything they can find to damage credibility. Not only is blue hair out, but even the color of her suits and style of shoes is dictated.”

This is an unfortunate reality of many jobs: there are certain appearance requirements that, if you fail to meet them, will inherently make you less effective at what you do. For better or worse, this is life in our society as it is today. It sounds like your wife could dye her hair blue if she wanted to bad enough, but there would be consequences, and she’s decided the consequences aren’t worth it. By the way, though, I did find this:

Image credit: The Lawyer Lifestyles website, via

There’s a website — and possibly a community — of people in professions like law who can’t fully express themselves and still be accepted professionally, who do their best to live their lives the way they choose outside of the courtroom while still appearing lawyer-ly inside the courtroom. For what it’s worth, my own choice-in-appearance has consequences, too, but they are minor enough that I’ve decided that living this way rises past the “worth it” line for me.

Image credit: J. Cummings, of Ethan Siegel in 2015.

From CFT on me, personally, and my appearance: “Having seen Ethan in his various costumes, I had at first assumed he was a themepark/videogame spokesman or mascot entertainer, or possibly an exhibitionist about to be arrested before I learned he was connected in any way to astronomy or science. In any case, If Ethan wants to distinguish himself, perhaps he should do so with the quality of his work, rather than the eccentricity his cosplay wardrobe.”

A good friend of mine never knew my profession until we had known each other for almost a year. When we were just talking and I mentioned something about being on the news to explain the landing of the Mars Curiosity rover, he was shocked! I asked him what he thought I did for a living. He told me, “I don’t know, I just assumed you were, like, a janitor or something.”

But you made assumptions (quite negative ones) about what I was (and what I was capable of) based on my appearance, which is my choice. Now that you know that I have an eccentric cosplay wardrobe (which some consider impressive), you still assert that I’m better off trying to distinguish myself through the quality of my work. Can’t I do both, without you negatively judging the quality of one from your distaste of the other?

Venus, Earth, the Moon and Mars to scale, images courtesy of NASA.

From Denier on Mars and the Moon: “Time for the ‘Mars bigger than the Full Moon’ hoax email to make the rounds again.”

Mars is always bigger than the Moon, full or empty! About twice the diameter… all the time. Of course, the hoax is that Mars will appear bigger than the full Moon, and that’s so not true that even if you confused arc-seconds (for Mars) with arc-minutes (for the Moon), the Moon is always larger. Not that I expect facts to change what people believe in this instance.

Varying views of Mars near opposition over the course of many years, from 1995-2005. Image credit: NASA/Hubble Heritage team, via

From Michael Richmond on Mars in the sky: “Alas, Mars will be at quite a southerly location in the sky, at Declination -21 degrees or so. Those of us in the northern hemisphere will have to look through quite a bit of the Earth’s atmosphere to see Mars during its opposition. The view from the southern hemisphere will be much better.”

The northern hemisphere doesn’t have it so bad! Those of us who get up early — while it’s still dark before the dawn — are already being treated to a spectacular triad of Mars, Saturn and Aldebaran in the southern parts of the skies in the early morning. Yes, the low declination means that people in the southern hemisphere get less atmospheric distortion, whereas someone up were I am (above the 45th parallel) has it much rougher. But it’s still a sight worth seeing, and the best views we’ll have of Mars until 2018, even with the additional atmospheric effects.

But yes, astrophotographers will have a much better opportunity to see this from, say, Chile than they will from the northern United States.

Image credit: NASA’s Goddard Space Flight Center.

From See Noevo on probabilities and errors: “In other words, that “0.22%” chance actually indicates that there’s a high probability this signal is, in fact, a false alarm.”
Ethan, I know this is outside your area of expertise, but how would you consider a 2,000,000.00% error/false alarm?”

I would consider those to be two entirely different things. When one speaks of probabilities, the number must be between 0 and 1, or 0.0% and 100%. So in the example I referred to, reporting a “detection” of 99.78% probability grossly underestimates the false positive signal and the lack of a signal observed by ESA’s Integral satellite, and so is much more likely to be false.

On the other hand, a 2 million percent error means you’ve got the wrong answer by a factor of about 20,000. Which is probably an indication that you’re using a lousy technique to measure the thing you’re attempting to find out. How do you interpret a 2,000,000.00% error?

Image Credit: SXS, the Simulating eXtreme Spacetimes (SXS) project (

From Ragtag Media on some fun pattern recognition: “Is that first image a Galactic Size pig poking his snout into our universe?”

It’s obviously Pluton from One Punch Man.

Image credit: screenshot from One Punch Man.

Although I suppose he’s not really as big as a galaxy, you have to remember — as Denier reminded us earlier — that angular size is all about perspective!

Image credit: NASA/International Space Station.

From PJ on the aurorae: “Having seen Borealis for many years out of Toronto, I appreciated the lights whilst living there. Thanks for the aerials; just a different and pleasant visual – brings back the memories.”

I only saw the northern lights once with my naked eyes: while traveling in Glacier National Park in Montana. In general, you need a combination of clear, dark skies and to be in a location within ~35-40 degrees of one of Earth’s magnetic poles. (Although there are exceptions.) Despite being at almost the same latitude as that park now, I have yet to see an aurora here. But for the ISS astronauts, they circle the globe from above about 15-16 times per day, and see pretty much every aurora there is. It’s not a bad view, from what I hear.

Image credit: NASA / WMAP science team.

From See Noevo on cosmic inflation: “It seems to me that this invention (i.e. Inflation) is considered to *surprisingly* find and fix the very things it was invented to find and fix.”

Or, you could read about the predictions it made that have been borne out since it was first proposed:

Note that it made six, and five have been confirmed. The sixth may not be, and that article details why.

Image credit: NASA / Johnson Space Center, of astronaut Karen Nyberg.

From Denier on Earth Day: “Have you noticed that the same people who scream the loudest about GMO crops seem to have no problem with the latest strain of Cannabis?”

People have their own blind spots about scientific evidence, and what they will or won’t conclude based on what they’d like the outcome to be on a particular ideological issue. I don’t think there are any scientific studies that could come out showing the robustness of the scientific evidence countering their own gut instinct that would convince them that they’ve taken up the wrong position on their pet issue.

Good thing we’re all above that, right?

Image credit: NCEP CFSR 1981-2010 Climatology / Ryan N. Maue / WeatherBELL.

And finally, from Ragtag Media doing his best Rick Astley impression, because he’s never going to give this thread up: “As a skeptic of man-made global warming, I love our environment as much as anyone. I share the deepest commitment to protecting our planet for our children and grandchildren. However, I desperately want to get politics out of the climate debate.”

Then you can start by looking exclusively at the full suite of scientific evidence about Earth’s climate, and at the full body of climate science work done by the full field of actual climate scientists, rather than any claims by meteorologists, celebrities, politicians, etc. unless they themselves are actual climate scientists, too. I like to fancy that’s what I did before arriving at the conclusions I did as respects climate science; I’m curious what conclusion you’d reach if that’s what you did?

No matter what you think, feel or believe, I hope you’ve had a great week and you’re stoked for the week ahead. I’ll see you then!