Sea Life Wiped Out by Neutron Star Collision?

Memorize writes "Scientists report in the Journal of Astrophysical Letters that a mass extinction of marine life 450 million years ago might have been caused by radiation from an exploding star, such as a collision between two neutron stars, or a neutron star collapsing into a black hole. Such an event would cause a ten-second burst of gamma radiation, and if it occurred within our galaxy, it could have wiped out many species on earth. At least if astronomers find out that an asteroid is heading our way, we can do something about it, but if there is a gamma burst, we get no warning. And if we did, would there be any way to protect the planet?"

Actually, it's not quite as dangerous as it sounds

[Anonymous Coward]

I posted the original story, and found this link after I posted it: Earthtimes story [earthtimes.org]. The 10-second pulse knocked out all the ozone, which allowed gamma radiation to bathe the earth for a few years afterwards, and that's what caused the extinction. If our lives depended on saving the ozone in a hurry, I'm sure it could be done. We would need to build an enormous number of huge nuclear reactors to work as ozone generators, but it could be done. I'm sure some enterprising Slashdotter could calculate how many it would take and how long to get them operational.

Must not be a good correspondant

[Crazieeman]

Alok Jha, science correspondent
Monday April 11, 2005

Next month, Nasa will launch the £138m Swift probe, which will sweep up to one sixth of the sky at a time, looking for sudden bursts. If all goes well, the probe could catch two three explosions a week.

Swift was launched almost 6 months ago.

Slashdot Link [slashdot.org]

Science.... fiction

[John Seminal]

I am not buying any of it.

From the article:

Gamma ray bursts are thought to be caused either when two neutron stars collide or when giant stars collapse into black holes at the end of their lives.

Then you get this:

Black holes do not exist

http://www.deccanherald.com/deccanherald/apr112005 /snt108532005410.asp [deccanherald.com]

So which one is it? Do black holes exist, or do they not?

Re:only half?

[Anonymous Coward]

The whole point of the article is that the gamma rays would instantly destroy the ozone layer, after which the UV radiation (from the sun) kills the little critters on the surface of the ocean over a longer period of time. Then the fish that used to feed on said critters will starve to death, and so on. It doesn't matter which side of the planet you're on...

Re:Scary Stuff

[Astro Dr Dave]

Gamma ray bursts are an area of active research; we now believe that they emit radiation along some polar axis, rather than isotropically in every direction. That probably accounts for the difference in distances you've seen quoted; for some fixed power level, an anisotropic GRB is dangerous from a greater distance if you happen to lie in the beam.

From TFA:

[DrJimbo]

First, this isn't just theory, they've measured gamma ray bursts from other galaxies:

For around 10 seconds, intense pulses of energy are fired off, which can be detected right across the universe. All the bursts recorded by astronomers so far have come from distant galaxies and are therefore harmless to the Earth.

Second, for all those posting that a 10 second gamma ray burst won't be lethal to all of us:

Such a burst would strip the Earth of its protective ozone layer, allowing deadly ultraviolet radiation to pour down from the sun.

They don't RTFA, and they don't read all the other posts saying the same stupid thing. What do they think this is? Slashdot?

it's the ozone layer, not the radiation

[cahiha]

Given a number of confused responses to this, let's just remind everybody: it's not the gamma rays that kill (they would only get half of the globe anyway), it's the stripping away of the ozone layer followed by intense UV radiation. That's why it's a global effect.

While that would cause huge famines and disease and kill almost all humans, it is something that our species could survive given our technology.

Re:I wonder...

[LurkerXXX]

Didn't you read the article? The "day" side would get fried by the gamma burst. The "night" side would be screwed in the coming years by having most of the ozone layer destroyed by the blast.

Half the planet (almost) instantly dead, the other side gets insta-sunburn the moment they walk outdoors for the next few years.

Re:No - we're doomed.

[xlsior]

It takes a good few inches of lead (or a good few feet of concrete, dirt, whatever) to significantly attenuate gamma rays - and if the ones were are talking about were powerful enough to get through the full depth of the earth's oceans and still kill things when they got there - then you'd need to wrap the earth in a few feet of lead - or hide down some amazingly deep mine-shafts

The article didn't say that the gamma rays themselves killed off life deep in the ocean, it just said that it killed of much of the plankton which lives in the first few feet in the ocean. Since the plankton is the bottom step in the food chain, it disappearing will starve a lot of small animals, which in turn means no food for the animals that eat them, etc.

Rinse & repeat all the way down the food chain.

Even life at the bottom of the ocean is dependend on what's going on near the surface. It may take a while, but eventually cataclismic changes near the surface will deplete much of the food sources in the deep as well.

Re:Binary pulsars and neutron stars do exist

[zennor]

The consensus among professional astronomers is still overwhelmingly in support of the existence of black holes.

Your second point about two neutron stars being unlikely to run into each other is not correct. Extensive studies of binary neutron star systems such as PSR B1913+16 and PSR B1534+12 provide stringent checks on general relativity. Each of these systems has two neutron stars orbiting each other with one of the pair also being detectable as a pulsar. Each component in the system is spiralling in towards the other.

The recent discovery of the first known binary pulsar system (see http://www.atnf.csiro.au/news/press/double_pulsar/ [csiro.au]) PSR J0737-3039 in 2003-4 using the Parkes radio telescope in Australia provides astronomers with an even better testbed.

In this system the two pulsars orbit each other every 2.4 hours, making them some of the fastest-moving stars known. As they orbit they lose orbital energy through gravitational radiation. They move closer together. The rate at which this happens can be determined and inital studies suggest the two pulsars will coalesce in about 85 million years. This system is about 1,600-2,00 light years or 550 parsecs distant from us. I can assure you that astronomers are actively observing and studying this system as it is allows them to test theories of gravity with incredible precision.

Neutron star collisions do/will occur and will produce strong gravity waves and most likely high fluxes of gamma rays.

There are now long-term projects monitoring pulse arrival times from pulsars across the sky with the aim of detecting gravity waves.

It doesn't seem quite so scary to me

[jesterzog]

Keep in mind the volume of a sphere is 4/3 pi r^3, so the volume of space that this would take up is increased by a factor of 8,000,000. I'd say, that the chance of this happening to us, therefore is increased by a factor of 8 million.

If the 6,000 LY limit is justifiable, I don't think it's quite as bad as you make out... at least not without some much more definitive research.

6,000 Light Years is practically next door on the galactic scale. It's certainly not infeasible (for someone qualified) to simply look at a survey of what's in our local space and determine immediately if we're at risk based on anything that looks unstable. (I'm not a professional astronomer, so someone's welcome to correct me if they know otherwise.)

The most obvious potential threat that's relatively close is probably Eta Carinae [seds.org], which is about as massive as it's possible to get, and it's been hypothesised in the past that there's a small chance we might be at risk from a sudden gamma ray burst from it. But it's still about 8,000 light years away and there's still not enough known about it to have any accurate idea of when it's going to blow itself apart, either tommorrow or millions of years from now.

If there's still a reasonable chance that it could happen at some point in the future, this doesn't mean that there's any chance at all of it happening tommorrow. Stars orbit move a lot relative to each other sa they orbit the galactic centre. Our Sun does that in about 226 million years, but in the space of hundreds of thousands of years, galactic material barely moves relative to each other at all. It's feasible that at some time in the next few million years or more we will be close to something dangerous for some period of time. If we're not close enough to it now, though, the chance of that happening is still zero.

This is all dependent on that 6,000 Light Year limit being correct, of course. Clearly it's still all subject to change as we learn more about the Universe, which we still know next-to-nothing about. I don't think there's much point worrying about the great unknown, though, at least until we know enough to know that there's actually a risk. Otherwise it would just lead to paranoia.

Loss of ozone

[erice]

Any gamma burst from a single point will only fall on half the Earth's surface directly. What stops us from just hopping across to the other half, instead of needing scifi tech to survive?

Short Answer: RTFA
Long Answer:

The Gamma rays would destroy the ozone on the unlucky side. Once the ozone redistbutes, you are down to 50% everywhere. That is, aparently, enough to kill plankton. Probably would kill land plants, too.

So, on the unlucky side everybody dies. On the lucky side, crops fail for several years. Very bad news, though I doubt it would actually exterminate the human race. Plants would still grow in UV filtered green houses.

The Danger is Not the Gamma Rays directly

[red_ninja2]

The real problem is ozone depletion and the formation of odd Nitrogen compounds, such as NO2. NO2 absorbs visible light (i.e. it gets dark and cold) and also steals ozone, O3, which is what saves our DNA from getting destroyed by UV light. Its not the gamma rays themselves that will kill us, they'll only last for 10 seconds and plenty of people will survive by simply being on the other side of the planet at the time. the radiation isnt going to cover the entire planet, but the argument they are trying to make is that it will make a hole in the ozone layer and might lower global temperatures. Here are some quotes from a preprint paper of theirs that I dug up at http://www.arxiv.org/ftp/astro-ph/papers/0503/0503 625.pdf "For some time, it has been known that high energy radiation may, through dissociation of N2 , create a variety of "odd nitrogen" compounds which lead to ozone depletion, making the atmosphere more transparent to solar UVB (290-315 nm) radiation. UVB is strongly absorbed by the DNA molecule and hazardous to life [e.g. Cockell 1999]." "Reid et al. [1978] noted two other potentially important effects, which have been acknowledged [Thorsett 1995] but not yet treated quantitatively in subsequent discussions of GRB atmospheric ionization effects. NO2 is one of the primary compounds formed. It has a major role in O3 depletion, but also absorbs strongly in the visible, giving it a brown cast. Such absorption may easily lower global temperatures, if sufficient NO2 is formed. Also, rainout of dilute nitric acid (HNO3) is one of the principal mechanisms of removal for the so-called "odd nitrogen" or "NOy" compounds formed. This can potentially contribute large amounts of biologically active nitrogen to the biosphere. The results are unpredictable but may be major, since biota are typically nitrate-starved and highly responsive to supplementation [Schlesinger 1997]"

Manifold Space

[DoubleReed]

The name of the book was manifold space. Great sci-fi, probably Baxter's best book. Dont read the other manifold books they are in no way part of a series.

I remember picking up that book and being floored by the fact that it starts off with the Fermi paradox. The downside is the plot is pretty morbid. I won't give away the ending but prepare to be underwhelmed with the rewards all of the main characters get for in some cases literally thousands of years of tireless effort towards the safety of humanity and life in general

Check the research article

[FleaPlus]

A pre-print of the research article [arxiv.org] is available. The impression that I get is that they don't claim to really "prove" the idea, but rather pose it as a very interesting hypothesis which is compatible with the evidence and deserves further investigation. In particular, I think their claim is that gamma ray bursts can explain the evidence of rapid cooling from the extinction period. Of course, the popular press claims this tentative hypothesis like it was already a concrete fact, but that's what the press does.

Here's the basic info:

Title: Did a gamma-ray burst initiate the late Ordovician mass extinction?

Abstract: Gamma-ray bursts (hereafter GRB) produce a flux of radiation detectable across the observable Universe, and at least some of them are associated with galaxies. A GRB within our own Ggalaxy could do considerable damage to the Earth's biosphere; rate estimates suggest that a dangerously near GRB should occur on average two or more times per billion years. At least five times in the history of life, the Earth experienced mass extinctions that eliminated a large percentage of the biota. Many possible causes have been documented, and GRB may also have contributed. The late Ordovician mass extinction approximately 440 million years ago may be at least partly the result of a GRB. A special feature of GRB in terms of terrestrial effects is a nearly impulsive energy input of order 10 s. Due to expected severe depletion of the ozone layer, intense solar ultraviolet radiation would result from a nearby GRB, and some of the patterns of extinction and survivorship at this time may be attributable to elevated levels of UV radiation reaching the Earth. In addition a GRB could trigger the global cooling which occurs at the end of the Ordovician period that follows an interval of relatively warm climate. Intense rapid cooling and glaciation at that time, previously identified as the probable cause of this mass extinction, may have resulted from a GRB.

Re:Scary Stuff

[mbrother]

Gamma ray bursts are likely a heterogeneous class. Some, surely, appear to be beamed radiation associated with supernovas. Some portion of them may well constitute isotropic sources, and would only be dangerous within some distance within our own galaxy. As an active area of research, and with SWIFT now flying, we should be getting better answers about the population demographics in the next couple of years.

Re:Scary Stuff

[Nick Barnes]

The Wikipedia article that you link to discusses the possibility of the PT mass extinction being caused by a supernova within ten light years of earth. The present article, on the other hand, is about gamma-ray bursts. Not the same thing. A gamma ray burst produces something like 1e47 Joules of gamma rays (actually 1e46 Joules per steradian; we don't yet know whether bursts are focussed or otherwise directional); a supernova only produces something like 1e41 Joules per steradian of gammas (a lot more than that of neutrinos, but who cares about neutrinos).

Re:Scary Stuff - Child rearing

[Mr. Slippery]

Stress is overrated.

No, stress kills [cbsnews.com].

People think they have it so hard these days. How about back when your food easily could kill you (mammoth trample), you had to run and struggle to catch your food, you had to walk miles everyday to get food, or move to a place with food or water, etc.

The difference is, those stresses your body/mind is adapted to.

About to get trampled by a mastodon? Bam! Adrenaline surge, you run, condition resolved and a few hours later your body chemistry is completely normal.

But we've created a world of constant low-level stressors, where our fight, flight, or freeze reactions won't help. Stressors are unresolved, so the alert mechanism is always on at a low level, diverting resources away from the immune system and the restorative mechanism.

Re:Scary Stuff - Child rearing

[Binestar]

But there are some up sides too!
Like...?

diaper changes in your 80's.

Re:Scary Stuff

[iwadasn]

It wouldn't be radiation poisoning. Gamma rays cannot penetrate our atmosphere. It would just remove about half the ozone layer (by converting Nitrogen gas into various nitrous oxides), which in turn would kill off a lot of plankton.

The effect on terrestrial life would probably be substantially less. Terrestrial plants are more resistant to UV, and terrestrial animals tend to have fur/clothes, so they are more resistant as well.

I'm not saying it isn't a bad thing, but we've pretty much achieved the same effect with all the hairspray needed to keep those 60s hairstyles in place.

Re:Scary Stuff

[Tlosk]

The reason we age is because there is no selection mechanism for longevity.

Not true, several people have suggested selection mechanisms for longevity. And it seems reasonable that they exist, even if the proposed ones are not those responsible. Why? Because we are capable of living decades after our fertility has ended. A small number of people with a trait and it can be argued that it nonselected, but when it is true of almost everyone in the population that argument becomes untenable. Unless by longevity you meant living forever.

For example:

Grandmother hypothesis
http://en.wikipedia.org/wiki/Grandmother_hypothesi s [wikipedia.org]