Humans close to finding answers to origin of universe: Hawking

[Fred]

Hawking is a bit of a public figure and likes to get press coverage. Hence he says things that are at times a little bit... well silly.

We are a long way from understanding the early universe, much less even what we observe today. There is still decades of work left to make astrophysics air tight, b/c as it stands now its still patchwork, with some things that we know and understand well (for instance big bang nucleosynthesis, and others that we don't have the slightest clue about eg darkenergy)

Keep in mind people are still actively trying to modify general relativity (past say solar system scales), that such attempts are even taken seriously is an indication that our basis is still sufficiently shaky.

Nevermind the theoretical issues with quantum gravity, which we will need to have pinned down theoretically before any hope of experiment can take place. My point of view is it will take another few hundred years to get it all sorted through and sufficiently agreed upon.

 

[KimB]

Chalnoth - what are some of the alternative ideas for changing the course of an asteroid?

You could attach a rocket to the asteroid (won't work for comets: no hard surfaces!), but we still won't know if the asteroid can take the strain.

You could use a large reflector to shine a light on one side of the asteroid/comet, like taking a magnifying glass to ants. This will melt a small part of the asteroid/comet, making a little jet which will propel it in one direction.

You could, of course, bombard the asteroid, but that is also at risk of breaking it up, which you do not want.

You could put a large spaceship near the asteroid, and use the gravitational attraction between the asteroid and your spaceship (which is under its own power) to alter the asteroid's course.

I'm sure there are more, these are just off the top of my head.

 

[K.I.L.E.R]

Those ideas were all mentioned on the documentary I watched.
Did you see it as well?

You could attach a rocket to the asteroid (won't work for comets: no hard surfaces!), but we still won't know if the asteroid can take the strain.

You could use a large reflector to shine a light on one side of the asteroid/comet, like taking a magnifying glass to ants. This will melt a small part of the asteroid/comet, making a little jet which will propel it in one direction.

You could, of course, bombard the asteroid, but that is also at risk of breaking it up, which you do not want.

You could put a large spaceship near the asteroid, and use the gravitational attraction between the asteroid and your spaceship (which is under its own power) to alter the asteroid's course.

I'm sure there are more, these are just off the top of my head.

 

[KimB]

Those ideas were all mentioned on the documentary I watched.
Did you see it as well?

Part of it, but the only idea I hadn't heard before was the gravitational attraction one.

 

[K.I.L.E.R]

It was mentioned, I remember.
It was also mentioned that all those ideas, even though theoretically good would have a high chance of failing.
How do we deal with that?

Part of it, but the only idea I hadn't heard before was the gravitational attraction one.

 

[KimB]

Detect the asteroid/comet many years in advance. That way we can try multiple things.

 

[K.I.L.E.R]

The problem is that it may take a few years before you can predict your next move, if the previous one fails.
It's insufficient to deal with.

There would also be large room for calculation errors simply due to the greater the distance, the smaller factors have to be taken into account far more accurately.
We'd probably end up using the world's processing power just to do minor calculations, which are partly needed to get the data right.

Even then, it would take a lot of time just to do a few parts of the calcuation.
I find the idea of being able to dodge an asteroid or commet attack with current tools and knowledge unrealistic.

 

[nutball]

There would also be large room for calculation errors simply due to the greater the distance, the smaller factors have to be taken into account far more accurately.
We'd probably end up using the world's processing power just to do minor calculations, which are partly needed to get the data right.

It's not the calculations per se which are difficult or subject to error -- orbital mechanics is very well understood and isn't particularly computationally expensive. The problem is acquiring sufficiently accurate data about the body's position and velocity, and doing so over a sufficiently long interval of time to ensure that we have the orbital elements nailed down.

If we perturb the orbit by whatever means then it will necessarily take a while (months possibly years) to measure what changes have been made and what implications those changes will have looking forward.

 

[predicate]

The problem, as I understand it, with scanning the sky for meteors is that there is so much sky but meteors are very small. The military scans the entire sky, but in nowhere near the resolution needed to pick up something like that far enough away for us to be able to do anything about it.

The number of 'near misses' is absolutely staggering, and we don't detect any of them until they've passed (there's some statistic like there being 10 meteors a year capable of extinction events that pass closer than the moon to earth every year, or something).

Statistically speaking, almost certainly the earliest we'd know about a meteor come to vapourise us is as it entered the atmosphere; which is around a second before impact.

 

[KimB]

That's not true. There are some astronomy projects dedicated to tracking these meteors, and we've found a large number of the ones that cross the Earth's orbit. Estimates are that we've found about two thirds of them.

It's somewhat nice, actually, that meteor-search missions piggy-back very nicely with supernova-search missions (since with both you're looking for a dim light source that wasn't there before, as with supernovae we're now looking for them so far away that they are quite dim indeed), and we've got a large number of supernova search missions in the works, since supernovae are one of the few primary experimental candidates for nailing dark energy.

 

[Guden Oden]

You could, of course, bombard the asteroid, but that is also at risk of breaking it up, which you do not want.

Why not? If it breaks up, chances are the pieces will miss earth altogether, or at least only do nominal damage. If it's hit hard and fast sufficiently far out, it'll be shooting at someone from a hundred meters range with a shotgun. Pellets will streak by your ears, but won't kill you.

Maybe best way to kill a killer comet is to accelerate something big and heavy right back at it. Strap a nuclear-powered rocket engine to a couple dozen tons of stone or metal, possibly attach a few H-bombs too while we're at it. Then we keep a couple "shots" a few days behind the initial one to take care of any big chunks that got away the first time.

If we do things right, there might only be gravel and icecubes left of it... Bring some scotch, pour yourself a drink!


The idea about focusing a beam of light on an incoming...whatever, how LONG exactly would we have to keep that magnifying glass pointed at it for that miniscule thrust to actually push it anywhere? Especially as it's bound to rotate around every axis there is, making the heating more difficult... I also wonder about that gravity attraction stuff. If we park a ship near an asteroid and wait for the two to attract each other, and then light an engine in the ship to keep it from smashing into the asteroid, the engine's exhaust would neccessarily have to blow onto the asteroid, thus pushing it away. Thereby at least partly defeating the purpose of parking the ship nearby in the first place.

Well, unless it's a WARP engine I guess, but if we had those, then Captain Kirk could save us!

 

[Deepak]

Slightly OT: Even if we find an intelligent communicable ET species, how to we do a (realtime) 2 way communication with them?

 

[Crusher]

The best way to protect the earth from an asteroid is to ask Superman nicely. The second best way is to send a team of drillers and astronauts up in special space ships to drill a hole in it and plant a nuke. The realistic way is to have a lot of people argue about what the best way is without being able to reach an agreement, have someone make an executive decision at the last minute that costs a lot of money, and then watch as it fails. Luckily it won't matter because the predicted path of the asteroid was wrong to begin with and it never hits the earth, despite our failed effort to change its course.

 

[KimB]

Why not? If it breaks up, chances are the pieces will miss earth altogether, or at least only do nominal damage. If it's hit hard and fast sufficiently far out, it'll be shooting at someone from a hundred meters range with a shotgun. Pellets will streak by your ears, but won't kill you.

No, because chances are you'll just break the asteroid up, not disperse it by enough to actually matter. Remember, the Earth is still some 7,000 some odd miles in diameter, and you'd have to get most of the asteroid to disperse by more than that, despite the fact that there will still be some gravitational attraction between the pieces. I don't think this is feasable for the larger asteroids that actually pose a threat.

And if most of the pieces do actually hit the Earth, the actual energy deposited will be somewhat greater than from one large impact (since from a large impact, you get many more pieces ejected into space, and their kinetic energy doesn't go into damaging things on Earth). Not to mention the damage will be more widespread.

 

[nutball]

Depends on the size of the fragments. Make them small enough and they'll burn up (fragmenting a large body into small components will increase the surface area and, theoretically, increase the specific rate of burn-up in the atmosphere).

 

[Nesh]

Hawking is a bit of a public figure and likes to get press coverage. Hence he says things that are at times a little bit... well silly.

We are a long way from understanding the early universe, much less even what we observe today. There is still decades of work left to make astrophysics air tight, b/c as it stands now its still patchwork, with some things that we know and understand well (for instance big bang nucleosynthesis, and others that we don't have the slightest clue about eg darkenergy)

Keep in mind people are still actively trying to modify general relativity (past say solar system scales), that such attempts are even taken seriously is an indication that our basis is still sufficiently shaky.

Nevermind the theoretical issues with quantum gravity, which we will need to have pinned down theoretically before any hope of experiment can take place. My point of view is it will take another few hundred years to get it all sorted through and sufficiently agreed upon.

Hawkings probably ment in some decades when he said we are near

Also we dont know in what aspect he ment "understanding the universe". It probably doesnt involve soleley exploration of space phenomenons but rather a combination of these and other things that might accelerate the studies.

For example a year or two ago some scientists said that they discovered that the DNA has a very similar structure to the universe.

Also the fibonacci sequence is used by some as a way to explain how the universe started and strangely I was told by my professor that some has even used it for prediction in the stock market and they were relatively greatly precise compared to econometrical predictions

There were also previous beliefs from religions that werent in the past accepted by scientists but are now. For example the logic of center everywhere with a periphery of no where. Or that everything is an expression of one and the same thing.

 

[KimB]

Depends on the size of the fragments. Make them small enough and they'll burn up (fragmenting a large body into small components will increase the surface area and, theoretically, increase the specific rate of burn-up in the atmosphere).

Well, sure. But if they all came from the same large asteroid, it's still the same amount of energy deposited (if not more). We currently believe that the impact of a large asteroid would heat up the entire atmosphere to around the boiling point of water or so...imagine what so many small fragments could do to it, if they're interacting directly with the atmosphere? What you're saying might work for a city-killer, but not a planet-killer.

 

[KimB]

Hawkings probably ment in some decades when he said we are near

Also we dont know in what aspect he ment "understanding the universe". It probably doesnt involve soleley exploration of space phenomenons but rather a combination of these and other things that might accelerate the studies.

For example a year or two ago some scientists said that they discovered that the DNA has a very similar structure to the universe.

Also the fibonacci sequence is used by some as a way to explain how the universe started and strangely I was told by my professor that some has even used it for prediction in the stock market and they were relatively greatly precise compared to econometrical predictions

There were also previous beliefs from religions that werent in the past accepted by scientists but are now. For example the logic of center everywhere with a periphery of no where. Or that everything is an expression of one and the same thing.

This all smacks of pseudo-science to me.

 

[nutball]

We currently believe that the impact of a large asteroid would heat up the entire atmosphere to around the boiling point of water or so...imagine what so many small fragments could do to it, if they're interacting directly with the atmosphere?

What is the heating mechanism of which you speak? Absorbing the KE in the atmosphere rather than kicking up cubic kilometres of particulates has a certain appeal. Afterall, what did really kill the dinosaurs?

What you're saying might work for a city-killer, but not a planet-killer.

There's no such thing as a planet killer. Or rather ... there hasn't been so far.

 

[KimB]

There's no such thing as a planet killer. Or rather ... there hasn't been so far.

Well, there is the object that hit so hard it split the Earth in two (the Earth and our moon).

Edit: But yeah, nothing like that is going to happen again. But there are asteroids and comets out there that are quite capable of extinguishing nearly all life on Earth.