Watched Nova last night...about gamma ray bursters.

Interesting show, mostly. But it does appear that PBS is struggling to compete with the likes of The Learning Channel and that new source of ubiquitous natural sensationalism, The National Geographic Channel.

I'll grant them the peotic license to add explosion sound-effects to a gamma ray burst in space...but what I could not get over was their sensationalistic bit toward the end regarding the catasptrophic effect of a nearby burst on the Earth. Pure hype!! (Not that it *couldn't* happen, but c'mon folks, that level of hype was pure fearmongering!)

I may have to review my tape (if I can stomach to before I erase it) but one astonomer implied that a burst more than a thousand light years away would probably not be dangerous to Earth. But the show went on to state how a GRB could "sterilize" an entire galaxy. Excuse me?

They gave quite a bit of airtime to a person I would consider a kook...sensationalizing the destructive effects as radiation would blind you, burn your skin, and obliterate all life on Earth in about 10 seconds. (Probably true, but what was the point of including this? It had NOTHING to do with solving the mystery of what GRBs are.) Then this kook went on to suggest that the reason we have not discovered other life in the universe is because GMBs are constantly sterilizing galaxies...of course ignoring the fact (along with many others) that our galaxy has, quite obviously, not been sterilized for approximately the last 1/3 the life of the universe...leaving open the possibility that at least a third of all galaxies have been happily evolving for several billion years. (That bit was, indeed, pure junk science and totally Bad Astronomy.)

The other problem I perceive is that most of the energy of the bursts is theorized to travel in two opposite jets...and not in an expanding circle of equally destructive radiation. In other words, you would not only have to be close to the GRB, but also in the path of one of the jets. Exactly how would this type of explosion sterilize an entire galaxy?

I did enjoy the real-life illustration of the scientific method...how early theories were formulated and eventually proved incorrect. That's the real stuff of science...not this propoganda intended to frighten people and up the ratings. Unfortunately, that seems to be the MO that "Nova" has chosen to follow.

Eric

I thought it was a good episode overall, particularly in showing the process of science and not just the end result. I agree that the "death star" bit was oversensationalized and unnecessary.

__________________
Everything I need to know I learned through Googling.

However, Arnon Dar is not a kook, but a noted astrophysicist.

Text companion article to topic on show

Summary of journal article (by the "kook") on topic

_________________
"... to strive, to seek, to find, and not to yield." - Tennyson, Ulysses



<font size=-1>[ This Message was edited by: ToSeek on 2002-01-09 15:12 ]</font>

I agree that this episode did good job of showing how science is done. It showed the blind alleys and frustration, not just the final result.

I also agree that the "death star" bit was over the top.

Well...there are a few "noted" scientists that I would consider kooks, but I won't go there. This is the first time I've heard of Dar so it's nothing to base a real opinion on. But along with the death star bit, I found his theory of GRBs sterilizing the universe to be over the top...in other words, kooky.

There is far better reasoning for our lack of discovering other life in the universe than that. They talked about it as if we should be able to (duh) obviously see intelligent life in, say, the Andromeda Galaxy but since we haven't, we need some exotic reason to explain it...when the fact of the matter, frankly, is that it is impossible for us for us to notice alien life more than 50 light years away even if they are screaming out their existence to us. Please, let us not dupe the general public into believing that our ability to detect alien life is far greater than it really is.

I also take exception to whoever stated flat out that a GRB could sterilize an ENTIRE galaxy, especially one the size of the Milky Way.

Since this is all in the realm of theory, it may be a misnomer to call it Bad Astronomy, but I do feel it was Misleading Astronomy.

Eric

I was wondering if they had originally made their calculations based on the energy that must have been released in the neutron model (where the energy could be expelled in all directions from a spherical body) rather than the total energy that would be released if the black hole model is correct (the energy would be expelled in two concentrated jets).

Then maybe they didn't readjust their thinking, so one of these bursters wouldn't be as powerful as they are thinking.

I actually enjoyed the show, although I agree it had several problems. I sort of got the impression that it wasn't accurately portraying the events that happened.

<font size=-1>[ This Message was edited by: aurorae on 2002-01-10 14:21 ]</font>

Frankly, my main objection to the presentation was that in the graphics, they showed bursters going off every few seconds... as if the universe was one big microwave oven full of gamma-ray popcorn...

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Although they talked about it a bit, they left off some important ideas about GRBs being beamed. One is that you need far less total energy than if we are detecting spherical explosions, since the energy is focused and aimed right at us. The other is that GRBs may be far more common than just one per day in the Universe; there may be hundreds per day, and we just don't see very many of them because they are aimed away from us.

Now that you remind me, that kind of bothered me, too.

Yes, that is what I was trying to say, I just didn't say it very well. The last bit, about the ones we see, is something else I thought of during the show but then when they described the model with the focused emissions they didn't even talk about it at all.

Heck, if we see one per day, that is a LOT. Presumably, unless the frequency has changed, there has been one per day, 365 per year, in the universe for billions of years. Then if we assume we only see a small fraction of the ones that occured...

Did the show even mention the one in February 1999 which had an optical burst that got to 9th magnitude? That shocked everybody! Had you had binoculars and were looking in the right place, you could have seen it (from a dark sky, but hey, that burst was millions/billions of parsecs away!). It was also imaged by Hubble; here is a page about it.

<font size=-1>[ This Message was edited by: The Bad Astronomer on 2002-01-11 16:38 ]</font>

I don't recall their mentioning that one in particular. The only mention they made of the bursters' optical counterparts was as part of the history of the field. Finding the first of those was an important milestone, and constrained the theories quite a bit.


<font size=-1>[ This Message was edited by: Donnie B. on 2002-01-11 17:38 ]</font>

I too enjoyed it, sans the hype. Truth be known, we were watching because my sister-in-law is a gamma-ray physicist at Caltech. She was interviewed for a BBC show last year and we were curious if the footage would show up on Nova...it didn't. She does study bursters and, I think, has found optical afterglows. But whenever "shop talk" comes up I lose her in about three sentences. I'll have to ask her if she saw the show (probably not) and what her impressions were.

Nova did a show a couple of years ago on extra-solar planets that had several of the astronomers at my workplace rolling their eyes. Most especially when Dan Goldin (Mr. Space Politics Extraodinaire) flatly announced that the Terrestrial Planet Finder would be giving us images of terrestrial planets around other stars that looked like images of Earth from orbit. What utter junk that was...TPF won't "see" more than specks of light, it is the spectra of that light that will be the remarkable stuff.

That episode also did a good job to diss said coworkers as they have done an incredible amount of work on the subject, including the proposals for TPF, but were hardly (or not) mentioned at all. Simply let it be said that astronomy is as political a field of science as any.

Eric

Eric, who is your sister-in-law? I might know her, and I will almost certainly know of her!

Fiona Harrison, at Caltech...they seem to think highly of her. She was awarded the Presidential Young Scientist Award a couple of years ago, and she just got tenure. We're all rather proud of her.

She's done some balloon experiments with GR detectors in the past and is also working on an X-ray survey in which they use Chandra data to look for optical counterparts to x-ray sources.

Eric

I missed the program, although my dad called
me up in the middle of it to tell me about
it (I don't have cable or an antenna, so I
couldn't see it myself), since that's my
field of study.

I did my thesis on rapid detections of x-ray
emission from GRBs using the RXTE satellite,
the same thing that BeppoSAX does, but since they did it first and got three times as many (larger FOV on their telescope), our group's effort never gets mentioned; it just complicates the story. Sigh.

Normally, it wouldn't bother me much, since,
after all, the BeppoSAX team did beat me to
it, except that it often happens that people
will show *my* results and *say* they came
from BeppoSAX. *That* ticks me off.

I'm disappointed the program chose to emphasize the "will the GRB destroy the
earth" question. Although it doesn't
surprise me. That seems to be the angle
they all like to go with. When I did a
press release about discovering a new
black hole candidate back in 1999, all
they wanted to know was "will it gobble
up the earth?", and that's pretty much all
the New York Times guy chose to write about.
Weird. One of these days I'm going to have
to actually sit down and calculate what the
energy flux from a GRB would be at the earth
if it happened nearby, and see what that
would do, if only because that's what
everyone always asks about. But that's not
a very interesting question.

And Fiona is way cool. Tell her I said
congrats on her tenure. If she even
remembers me. :-) We have met a couple
of times.

Don Smith

As well they should! Yes, I do know her; we attended the same conference in Baltimore last year. She gave a very good press conference on high energy astronomy. Small world! Well, tell her I said hi next time you talk to her (she may not remember me; tell her my boss is Lynn Cominsky).