Is the universe meant to be sterile ?

[antisocial one]

This thread is about natural events in universe that could destroy life on earth or any other life.

This is topic I am intested in since ever so I am asking is somebody here intrested in this topic a well. But I am looking for PURE SCIENTIFIC CONVERSATION.
And I what to know what people think about this, what events they consider more dangerous then others for life and consider this thread to be exploration of possibilitys.

This thread is continuation of another thread but everybody are wellcome. By this I mean that people who just whant to know more are also welcome. But I am hoping for a debate between people who know more about this topic.

To give something to start: I have on another thread said, that whit time neutron stars will become problem for life because "concentracion" of binar neutron stars will be growing whit time and when two of them crash togather they create very large ammount of radiation.

Feel free to attack my statement because I whant know if I am right.

[Aronnax]

Didn't I already go over this? It's not a serious concern, within the arm of orion (aprox a 2K LY radius about sol) there aren't very many binary systems that are within the proper mass range to form a double neutron star system. Even if they're the proper mass they still have the formation and collision hurdles to overcome.

[antisocial one]

Didn't I already go over this? It's not a serious concern, within the arm of orion (aprox a 2K LY radius about sol) there aren't very many binary systems that are within the proper mass range to form a double neutron star system. Even if they're the proper mass they still have the formation and collision hurdles to overcome.

Yes you did go over this but now I am asking everybody else now. Plus this thread is not just about this. It is about black holes, asteroid impacts and........
I will not hide that this is just my hobby not profession.

Now to finally say my point.
Yes this scenario that neutron stars crash in each other is very unlikely but when it happens very large area is effect. Also there is point that sun is not eternal so some expansions will have to be made in far future. I never said that this is problem in present but maybe it will be in future.

Now about collision itself. If stars are not too close to each other supernova should not destroy its "partner". Few years ago it was even announced that they found planets around pulsar wich somehow survived the explosion. But I am not investigateing this so I dont have any links. Tomorrow I will try to find some of them.
My point is that if this turns out to be truth "couple" can explode one by one creating binar neutron star system. But that is only when they have proper mass to become NS and if I still remember correctly that is beetween 1.4 and 3 or 5 or 8 sol masses. I books numbers are diffrent from each other so I dont know wich one is right.
But if stars go nova then some mass is taken away.
Even if they stay in same orbit after explosions(wich are two separated events) their size has changed.
Gravity works between all particles and it is changed by distance. That means that force is changing its strength whit this. That means if sistem was stabile then it is not completly stabile now and that should lead to inescapable crash, because gravity is too strong for stars to separate completly but in some cases it could happen but all of this "dancing" will last for very long time. There are many possible scenarios depending on masses, distance, speeds, ....

You have mentioned collision whit Andromeda wich will be in some 2.5-3 billion years.
Ok,but that is perfect mechanism to destroy balance in that sistems and as two galaxys merge togather concentraton of that kind of sistems will raise.
I am not saying that all of this is certain doom but it could be because it is hard to hide or fun from its huge radius. But if tehnology continue like in last 100 years we have nothing to worry about.

[Aronnax]

Yes this scenario that neutron stars crash in each other is very unlikely but when it happens very large area is effect. Also there is point that sun is not eternal so some expansions will have to be made in far future. I never said that this is problem in present but maybe it will be in future.

If humanity is at a point where we've spread out far enough that we have to worry about stars outside of Orion's arm then we've dispersed enough to protect ourselves from that kind of event.


Now about collision itself. If stars are not too close to each other supernova should not destroy its "partner". Few years ago it was even announced that they found planets around pulsar wich somehow survived the explosion. But I am not investigateing this so I dont have any links. Tomorrow I will try to find some of them.

Even if the stars are locked in a binary system but far enough apart to survive one going supernova the supernova can blow mass away from it's partner, dropping it below the neutron star mass threshold. Active stars have a low surface density, it's much easier to remove part of that low density material than blow apart a planetoid with an iron core.


My point is that if this turns out to be truth "couple" can explode one by one creating binar neutron star system. But that is only when they have proper mass to become NS and if I still remember correctly that is beetween 1.4 and 3 or 5 or 8 sol masses. I books numbers are diffrent from each other so I dont know wich one is right.

The higher numbers refer to the size of the star before death, the lower numbers refer to the stellar mass of a neutron star.


But if stars go nova then some mass is taken away.
Even if they stay in same orbit after explosions(wich are two separated events) their size has changed.
Gravity works between all particles and it is changed by distance. That means that force is changing its strength whit this. That means if sistem was stabile then it is not completly stabile now and that should lead to inescapable crash, because gravity is too strong for stars to separate completly but in some cases it could happen but all of this "dancing" will last for very long time. There are many possible scenarios depending on masses, distance, speeds, ....

If you reduce the mass in the system their hold on one another via gravity would become weaker causing them to drift apart, not draw closer together. There are double neutron systems that can collide out there but they're not common.


You have mentioned collision whit Andromeda wich will be in some 2.5-3 billion years.
Ok,but that is perfect mechanism to destroy balance in that sistems and as two galaxys merge togather concentraton of that kind of sistems will raise.
I am not saying that all of this is certain doom but it could be because it is hard to hide or fun from its huge radius. But if tehnology continue like in last 100 years we have nothing to worry about.

When galaxies collide the individual systems, for the most part, remain unaffected because galaxies are basically giant voids sprinkled with matter. The potentially fatal consequence for us would be if the collision deposited matter close enough to the center of the galaxy to move the super massive black hole at the center into an "active" phase. When a super massive black hole is feeding it's a quasar and the amount of radiation they pump out is incredible. Then again that's one of the "we can worry about it in 3 billion years" kind of problems.

[antisocial one]

Sorry for not posting I had some problem with my computer.


If humanity is at a point where we've spread out far enough that we have to worry about stars outside of Orion's arm then we've dispersed enough to protect ourselves from that kind of event.


Even if the stars are locked in a binary system but far enough apart to survive one going supernova the supernova can blow mass away from it's partner, dropping it below the neutron star mass threshold. Active stars have a low surface density, it's much easier to remove part of that low density material than blow apart a planetoid with an iron core.


The higher numbers refer to the size of the star before death, the lower numbers refer to the stellar mass of a neutron star.


If you reduce the mass in the system their hold on one another via gravity would become weaker causing them to drift apart, not draw closer together. There are double neutron systems that can collide out there but they're not common.

When galaxies collide the individual systems, for the most part, remain unaffected because galaxies are basically giant voids sprinkled with matter. The potentially fatal consequence for us would be if the collision deposited matter close enough to the center of the galaxy to move the super massive black hole at the center into an "active" phase. When a super massive black hole is feeding it's a quasar and the amount of radiation they pump out is incredible. Then again that's one of the "we can worry about it in 3 billion years" kind of problems.

1. True but what I whanted to say is that if we dont create fast transportation it is hard to get away from problem and if you are really slow you will be running from one danger to another one.

2. In this case stars must be far from each other if we whant to prevent crash before supernova.
You are saying that supernova can blow of 200 000 times more mass than planet from star wich is futher away then destroy close planet.
Also I always thought that all those detected planets out ther are gas giants.
Neutron stars are one of the most massive objects in universe so finding terestrial planet in difficult task.
Planets were found around single neutron star but in binar sistem there should not be any because forces of two stars make impossible to have stabile orbits.
So so we should stay out of this it does not matter in this.

3. That means all neutron stars have same mass = 140% of the sun one.
Where did you get this?

4. I think this is all about the speed if they are too slow then gravity will not be enough.
If gravity is weaker that does not mean much because supernovas and change of sizes destroyed balance of the forces in sistem that once was there.
That means that every gravity is enough for crash whit enought time.

5. That is also true.
But my point was that even very small influence can destroy balance or speed up process by even more destroying balance with increased density of that part of galaxy.

[rwyatt365]

So far, the discussion has revolved (mostly) around purely technical and probabilistic arguments for and (mostly) against your opening question of whether the universe is meant to be sterile or not. I don't have enough astrophysical knowledge to contribute meaningfully to that.

However (don't you just love that word!), this question started me thinking - is life an abberation, or inevitable in the universe? My highly biased, and totally unscientific opinion is that "Life will find a way". Given the timeframe of evolutionary processes compared to changes at a universal level, life should have plenty of time to adapt to those changes (intense radiation, extreme heat and/or cold, lack of energy sources, etc..) up to the limits of physical capacity. Who knows what exotic forms life could/would adopt in an effort to survive? No one thought that anyone would find giant tube worms on the floor of the ocean, but there they are (to put an earthly face on my argument). Is anything possible? I would suggest that the answer is "yes", given enough time and a source of energy (however small).

[antisocial one]

So far, the discussion has revolved (mostly) around purely technical and probabilistic arguments for and (mostly) against your opening question of whether the universe is meant to be sterile or not. I don't have enough astrophysical knowledge to contribute meaningfully to that.

However (don't you just love that word!), this question started me thinking - is life an abberation, or inevitable in the universe? My highly biased, and totally unscientific opinion is that "Life will find a way". Given the timeframe of evolutionary processes compared to changes at a universal level, life should have plenty of time to adapt to those changes (intense radiation, extreme heat and/or cold, lack of energy sources, etc..) up to the limits of physical capacity. Who knows what exotic forms life could/would adopt in an effort to survive? No one thought that anyone would find giant tube worms on the floor of the ocean, but there they are (to put an earthly face on my argument). Is anything possible? I would suggest that the answer is "yes", given enough time and a source of energy (however small).


From idylic point of view I would agree whit you. But I was doing alot of reading about this topic and realised that chances for life to survive forever could be 0%.
For example modern models predict that whit time there will not be stars to produce light or heat.
Professionals call this a eternal night.

So I am thinking alot about it and I started this thread to find some diffrent or same thinking.

[Aronnax]

1. True but what I whanted to say is that if we dont create fast transportation it is hard to get away from problem and if you are really slow you will be running from one danger to another one.

I believe you missed what I was saying.

I said where we're at in the galaxy there isn't a serious threat.

You countered with the fact that the sun isn't eternal so we may end up in a place where a double neutron star collision is possible.

I countered with the fact that if we're move far enough away (outside of the ~2K ly radius of Orion's arm) that it becomes an issue then we'll have spread out far beyond the destructive radius of any collision.


2. In this case stars must be far from each other if we whant to prevent crash before supernova.
You are saying that supernova can blow of 200 000 times more mass than planet from star wich is futher away then destroy close planet.


It doesn't have to blow 200,000 times more mass away, it just has to remove enough to drop it below the mass threshold for a supernova. Additionally yes, it's possible for a solid to survive a higher level of force than an object that behaves like a fluid. Think about how hard you have to hit a rock to get it to shatter compared to a pile of pudding.


Also I always thought that all those detected planets out there are gas giants.
Neutron stars are one of the most massive objects in universe so finding terestrial planet in difficult task.

We've found large solid planets but the majority have been gas giants. We detect distant planets by the gravitational effect of the planet on the parent star so they have to have enough mass to have an observable effect. To detect an exosolar planet it needs to have a lot of mass so our detection techniques favor gas giants. Gravitational microlensing offers some interesting opportunities for discovering smaller rocky planet but with current techniques (observing solar wobble) the "smallest" rocky planet I know of is about 5.5 times as massive as earth.

Gas giants also aren't necessarily all gas, many believe that they have a solid core so even if you blew away part of the gaseous shell there'd still be a planetoid there. The planets detected around neutron stars are believed to be formed out of the remnants of the supernova or are the rocky cores of gas giants located in a large orbit.

Neutron stars aren't really that massive, there are lots of normal stars that have more mass. Neutron stars are very dense but the effect they'd have on a body in orbit isn't any different than a large star.


Planets were found around single neutron star but in binar sistem there should not be any because forces of two stars make impossible to have stabile orbits. So so we should stay out of this it does not matter in this.

This is true.



3. That means all neutron stars have same mass = 140% of the sun one.
Where did you get this?

There's a mass range, but neutron stars tend to fall between 1.4 and 3 solar masses. If they're much bigger they don't become a neutron star, they become a black hole. If they're much smaller and they can't generate enough force to overcome the interatomic forces to collapse the atoms down to neutronium.

The honest answer is I got this from memory. I have 2 astronomy texts sitting on my shelf right now, it's either in "Physical Universe: An Introduction to Astronomy" or "Galactic Dynamics". If I had to guess it's probably in "Physical Universe: An Introduction to Astronomy".




4. I think this is all about the speed if they are too slow then gravity will not be enough.
If gravity is weaker that does not mean much because supernovas and change of sizes destroyed balance of the forces in sistem that once was there.
That means that every gravity is enough for crash whit enought time.


Draw the free body diagram for both mass systems.

In order for there to be a stable orbit the orbital velocity has to generate force equal to the force of gravity between the bodies, the system begins in equilibrium.

If you apply the force from the supernova explosion from one star onto the other, it will directly oppose the direction of the gravitational attraction. It cannot push them together, it can only push them farther apart.

If you examine the force system for a supernova the ejection and implosion forces are distributed relatively evenly, there shouldn't be a large applied force in any direction so acceleration due to applied force should be negligible. You can change velocity by changing mass since it effects momentum but mass is ejected evenly and should have equal momentum in the direction of orbit so mass ejection shouldn't significantly effect velocity either.

In short there's no force in this system that would make them come together if they started in a stable orbit.

The only theories that make a collision possible without an eternal force acting on the stars involve gravitational decay which falls into the "very theoretical" end of physics.

However (don't you just love that word!), this question started me thinking - is life an abberation, or inevitable in the universe? My highly biased, and totally unscientific opinion is that "Life will find a way". Given the timeframe of evolutionary processes compared to changes at a universal level, life should have plenty of time to adapt to those changes (intense radiation, extreme heat and/or cold, lack of energy sources, etc..) up to the limits of physical capacity. Who knows what exotic forms life could/would adopt in an effort to survive? No one thought that anyone would find giant tube worms on the floor of the ocean, but there they are (to put an earthly face on my argument). Is anything possible? I would suggest that the answer is "yes", given enough time and a source of energy (however small).

I tend to agree with the concept that "life will find a way" once it gets a foothold. Anaerobic bacteria in soil and chemosynthetic processes deep underwater demonstrate that life will dig in wherever it can and isn't nearly as fragile as we make it out to be.