Is it *possible* that the Sun could break up? Yes, but it would take a truly extraordinary set of circumstances for that to happen. Anything that would cause that (and I can think of only two off the top of my head--a black hole or another very massive star wandering into the neighborhood) would also make life on Earth very interesting and intense--for a very short period of time.

So how do we know that the Sun has a few billion (5 or 6) years left? Largely because of the mass of the Sun. To understand how this relates, we have to digress and talk about stars generally.

A star is simply a ball of plasma (matter in a very energized state) held together by gravity. The energy is provided by the fusing of hydrogen into helium. At the heart of a star, there is a wrestling match--gravity wants to collapse all of the mass of the star into the smallest possible space while heat wants to expand the star. Stars on what astronomers call the 'main sequence' are happily fusing hydrogen into helium. However, in ANY process there is is loss due to inefficiency. So as the star burns it begins to lose mass. Remember that mass is what is creating the gravity so as the star loses mass, pressure begins to win.

Because our Sun is a very ordinary star (it is a G-type dwarf star, the second or third most common type star in the universe) we have a lot of observational data from different stars like ours at different stages of life. Given a particular burn rate (and we know the burn rate of the star by the spectral lines--the light we see from the Sun is only part of the EMF spectrum being put out by it) we can determine at what rate the Sun is losing mass.

The end-game for a star is determined by its mass. For an ordinary dwarf star like ours, the end-game looks like this:

Around 5 or 6 billion years the Sun will have lost enough mass that pressure will, temporarily, have the upper hand. The outer shell of the Sun will then expand out to 1 AU (Astronomical unit which is 93 million miles). This is inconveniently the orbit that Earth occupies. It will then be a red giant star. Over the course of another billion years or so, it will burn off the rest of the helium and slowly collapse back into a white dwarf. This will basically be only the core of the Sun and will be about the size of Earth (although MUCH more massive than Earth is). Over the next few billion years, it will cool down through a brown-dwarf phase until it is a black-dwarf.

Within a reasonable margin of error (say 1% either way) we're pretty certain when the Sun will begin its end-game because of its present mass and heat.

Just because it is SO cool, I'll take you through the end-game of a much more massive star than ours.

REALLY massive stars (like Betelgeuse) have a much more interesting life cycle. They still stay on the main sequence H --> He but once they reach the Helium stage (where that's the only fuel that is left) it will begin fusing Helium into Carbon. This transformation keeps happening until the core becomes Iron. At that point, there's no place else to go. No natural force and fuse Iron into a heavier element and gravity gets the upper hand. The core collapses into itself and the resulting energy release is called a supernova. The star *literally* blows itself apart. If the star has sufficient mass, after the cataclysm of the supernova a black hole or a neutron star will result. A black hole results if the remaining core has sufficient mass to continue collapsing. Otherwise all that is left is a superdense core of neutrons known as a neutron star. These completely exotic objects are some of the strangest things in a very strange universe. They are so dense that a single teaspoon of the stuff would weigh as much as the Earth!

Cheers
Aj

Well, it depends upon what you mean. You, me, everyone in fact most *interesting* features of the Universe are made from the remains of supernova. As a very massive star goes through its end-game it makes all of the heavier elements on the periodic table (everything heavier than Helium). So all of the carbon in your body was once in a supermassive star that exploded. All of the oxygen you are breathing came from the same kind of source. So in a very limited and technical sense yes, all of the matter that we are made of and that sustains us is our creator. We are its creation. Billions of years ago some star burned its fuel, fell into the run-away iron-cycle end-game and then exploded. In the fullness of time that material became the Earth and the other planets.

To the degree I am at all deistic, it is that the Universe is the creator. Now, I don't think that the Universe notices we are here other than in the limited sense that living organisms interact with one another. In as much as you are part of the Universe and I am part of the Universe and we are aware that the other exists, the Universe is aware of our existence. In as much as I love my wife and my wife loves me, the Universe cares about my continued existence. But outside of those interpersonal interactions, I don't think the Universe is intelligent or aware of our existence. Supernovae happen not so that there can be life, it's simply a by-product. Earth isn't here so that there *can* be life, life exists because Earth happens to have a range of environments and is stable enough for life to have a chance to get going.

Cheers
Aj

Speaking of Life on Earth, is there life out there? Do you think it would be as aggressive as Hawking stated:

Found on wikipedia:

In planetary astronomy and astrobiology, the Rare Earth hypothesis argues that the emergence of complex multicellular life (metazoa) on Earth required an improbable combination of astrophysical and geological events and circumstances. The term "Rare Earth" comes from Rare Earth: Why Complex Life Is Uncommon in the Universe (2000), a book by Peter Ward, a geologist and paleontologist, and Donald E. Brownlee, an astronomer and astrobiologist. Their book is the source for much of this article.

The rare earth hypothesis is the contrary of the principle of mediocrity (also called the Copernican principle), advocated by Carl Sagan and Frank Drake, among others.[1] The principle of mediocrity concludes that the Earth is a typical rocky planet in a typical planetary system, located in an unexceptional region of a common barred-spiral galaxy. Hence it is probable that the universe teems with complex life. Ward and Brownlee argue to the contrary: planets, planetary systems, and galactic regions that are as friendly to complex life as are the Earth, the solar system, and our region of the Milky Way are very rare.

http://en.wikipedia.org/wiki/Rare_Earth_hypothesis

I have to say that I would be absolutely stunned if there were no life anywhere else in the universe. The sheer range of environments that life can cling to here on Earth actually suggests that life would have quite a bit of opportunity to get booted up. Consider:

Living things survive in environments as diverse as the bottom of the ocean, next to volcanic vents where superheated water containing high levels of sulfure provide a habitat for tube worms and bacteria to the inside of reactor cores (there is a species of bacteria, Deinococcus radiodurans) that thrive in high radiation environments. There are salt-loving bacteria, sulfur-loving bacteria (some of which are in symbiosis with the aforementioned tube worms). So I think that life probably exists elsewhere in the universe.

I'm even willing to venture so far as to say that intelligent life probably exists somewhere else. Our primary adaptation, the reason why we are such a spectacularly successful species (so far) is our adaptability. That adaptability we call intelligence. Intelligence is SUCH a neat trick that it would quite remarkable if some other species, living in who knows what kind of environment, hadn't hit upon intelligence in the course of their evolutionary history. So would another intelligent species be as aggressive as Hawking suggests? That depends.

There's a couple of schools of thought on what to look for in another intelligent species. For one, taking a naturalistic view any extraterrestrial species we might meet would *also* be a product of evolutionary forces. Evolution doesn't necessarily favor nice guys. It doesn't necessary reward complete bastards either. In most game-theory based models what seems most stable is tit-for-tat. If you cooperate with me, I'll cooperate with you. If you stab me in the back, I'm either going to get retribution OR I'm going to let others know you're not to be trusted. Grant, for the moment, that other species would probably hit on some kind of similar solution.

One school of thought says that intelligent species pass through stages of civilization. The stages were originally proposed by a Russian named Nikolai Kardaschev and the scale is called the Kardaschev scale. It measures total energy output used by a civilization. The scale is four stages (originally three) which are:

Type 0 civilization--this is where we are right now. We are actually at about .72. More on this in a bit.

Type 1--This civilization can use all of the energy available on their planet. This could be achieved through the use of fusion power, power generated from naturally collected anti-matter or space-based solar arrays which would allow us to use much higher proportions of the Sun's energy than we do now.

Type 2--This civilization can use all of the energy available in their solar system. The most common example of this is the Dyson sphere. The idea behind a Dyson sphere is that a civilization breaks down all the other planets in the solar system and uses those to construct a sphere around its primary star. That way ALL of the star's energy is trapped in the sphere and can be put to use. The civilization lives on the inside of the sphere.

Type 3--This civilization can use all of the energy available in their local galaxy.

Another proposed scale is from Robert Zubrin. It is still a three-stage scale but instead of looking at the energy consumption, looks at how far the civilization has spread.

Type 1--Has spread across its entire planet.

Type 2--Has spread across its entire solar system.

Type 3--Has spread across its galaxy.

So, using the two scales applied to science fiction civilizations (since they are familiar enough to most people)

Human civilization is type 0 according to Kardaschev scale and Type 1 according to the Zubrin scale.

The Federation of Star Trek is a type 2 civilization using the K-scale and type 3 using the Z-scale.

Both the Galactic Republic and the Galactic Empire of Star Wars are type 3 civilizations using either scale.

The Ancients in Stargate are most likely type 3.

Here's the challenge--getting from type 0 (where we are) to type 1 (or type 1 to type 2) depending upon the scale you prefer. IF we manage to neither blow ourselves to kingdom come or create our own little Venus here then in another hundred years we'll become a Type 1 civilization according to the K-scale. I think that any civilization that manages to get that far will probably persist indefinitely. So the optimistic view would be that if we were ever to encounter a type 2 or type 3 civilization, they would simply be too mellow and evolved to conquer us.

The less optimistic view, though, is that any type 2 or type 3 civilizations we might encounter here are going to be here for a reason. I can't imagine why any civilization would go to the trouble and expense to travel possibly hundreds of light-years JUST to see the sights. If an alien civilization comes to Earth it would likely be because Earth has something that they want/need and cannot synthesize themselves. If that is the case, the best we could hope for is that they would relocate us someplace and then take the planet for themselves.

Also keep in mind that a type 2 or type 3 civilization would have technology so far advanced from ours that we would all have full and complete appreciation of Clarke's Third Law, "Any sufficiently advanced technology is indistinguishable from magic". I think that if we were to encounter a type 3 civilization we might be very likely to fall upon our knees and worship them as gods as they would be able to do things to and with matter that we can hardly fathom. If we gave them any guff, however, sweeping us aside would be no more trouble than, say, any modern military would have sweeping aside the armies of Caesar or Hannibal. Imagine the modern US military transported back a few thousand years to the time of Caesar. They would appear as gods to them.

Hawking makes a really good point. As much as we may romanticize why the Europeans, Chinese, Persians and Ottomans set out on their voyages of exploration they were looking for resources, fortune and glory. They weren't just seeing the sights, that was an interesting by-product. Whenever or wherever those three groups found people who were inconveniently in the way they either destroyed them or conquered them. I suspect that any intelligent species that went to the trouble of traveling here would probably do the same.

One other option--and this was a point that Hawking made and other scientists also made after a couple of instances where NASA or some other group of scientists sent messages into deep space saying "here we are"--is that a civilization might detect us and decide that BEFORE we become a problem in the galaxy, they might want to just save themselves the trouble and wipe us out now while we are still not much more than monkeys with nuclear weapons, some satellites and digital-fiber optic technology. It would certainly be tempting particularly if the species were aggressive. Using the Star Trek universe as a guide, I could see the Vulcans wiping us out because it would be easier to do so now than AFTER we developed FTL travel. I could see the Romulans doing so for much the same reason. I could see the Klingons doing so because we would look like the competition and it would be a nice exercise for young Klingon warriors. :)

Cheers
Aj

[QUOTE=The_Lady_Snow;269886]Dear dreadgeek,


Could you explain the phenomena of [B]Déjà vu????


The déjà vu illusion occurs when a person has an inappropriate feeling of familiarity in a situation that is objectively unfamiliar or new. The amorphous nature of this experience has made identifying its etiology challenging, but recent advances in neurology and understanding of implicit memory and attention are helping to clarify this cognitive illusion. More specifically, déjà vu may result from (a) a brief change in normal neural transmission speed causing a slightly longer separation between identical messages received from two separate pathways, (b) a brief split in a continuous perceptual experience that is caused by distractions (external or internal) and gives the impression of two separate perceptual events, and (c) the activation of implicit familiarity for some portion (or all) of the present experience without an accompanying conscious recollection of the prior encounter. Procedures that involve degraded or occluded stimulus presentation, divided attention, subliminal mere exposure, and hypnosis may prove especially useful in elucidating this enigmatic cognitive illusion. [ABSTRACT FROM AUTHOR]

Brown, A.S (2004). The Déjà Vu illusion. American Psychological Society, 16: 256-259.

Thanks AJ for your excellent replies. That quantum foam thing has tripped me up and you helped very much to clarify!

As to the antimatter, clearly I watch too much Star Trek.

Thanks again!

PS this thread is SO giving me a brain wood

I've always been curious....

Does "Electroweak Breaking" Affect the Macroscopic World?

I love to cook and so I'm always interested in the science of food.

I've always wondered two things:

1. What is the science behind churning butter? How does the churning turn cream into butter? What are some of the molecular changes going on?

2. Who figured this out? How do you accidentally churn and churn cream until it becomes butter?

Rufus

Daywalker - I think you would love the poetry of Whitman and William Blake. They both have the idea that the creator and the creation are the same thing. They argue for Poets replacing priests and institutionalized religion and people learning to value and be in awe of the natural world of which we are a part (hence Whitman's odes to the body, sex, and life) and Blake's awe of art (as creation), and the natural world.

Rather than worrying about an afterlife and keeping an unknowable god figure happy they tell us to revel in life itself and that "god" is in us and in everything we see and to worship that and not some arbitrary angry figure that demands we do X but not Y in order to have an afterlife.

Blake (late 18th century) was an anti rationalist because he said they reduced life to nothing but atoms and molecules and diagrams and theories. In one of his paintings, Blake has Newton looking down at the ground creating a diagram. In this picture, Newton has lost his creative imagination and has lost his capacity to be in awe of and in wonder of the natural world and in doing so has lost his humanity. For Blake, true humanity was located in the creative arts and in the human imagination.

Melissa

As I was kindly reminded, I am sorry if I had the nerves to answer some questions... I will not participate in this thread... the only thing I have to say though, it would be nice to have seen some sources or articles related....

Buhbye

[quote=Softhearted;269911]

Rufus has a theory that deja vu is related to DNA. Since all our likes and dislikes and preferences are related to genetics then deja vu is a genetic memory. We think we have seen or done something before but we are just flashing to gentically passed likes and dislikes, almost like a genetic memory. Just theory of course but I like the idea. What do you think?

Melissa

I refuse to say "Science Wood" because it makes me uncomfortable. Putting it in quotation marks does not count as saying it.

Dear Person Who Likes Science:

Since we know that Sundowning (the tendency toward increased abnormal behaviours from a person with Dementia in the late afternoon or night time) exists and is real, and since we think that the Lunar Effect (the tendency toward increased abnormal behaviours from a person with Dementia or mental health issues related to the full moon) MIGHT be a little bit real - Is it fair to say that there is a little bit of science behind astrology?

I mean, surely if moon phases and time of day can effect people...it's not completely unreasonable to say that the position of the planets and/at time of birth can lead to some predisposition of personality types?

Sorry folks
 

I have to catch up. I don't spend as much time online during the weekend as I do during the work-week so it may take me a bit to get up to speed. :)

Cheers
Aj

June:

Actually, this is not quite correct. The Earth forms and then over a period of time, gets bombarded by comets (which is where the most likely came from). Now, as far as mass being added by the living things actually that's not the case. All of the mass in your body and in the bodies of other living things was already present on the planet. Here is where the conservation of energy comes in. Right now, chances are, one of the oxygen atoms you've just inhaled was breathed by a Caesar, or some Roman slave from the time of Caesar. All of the activity you've spoken of--comets and asteroid collisions notwithstanding--redistribute the mass of the planet without actually adding or reducing the total mass.


Strictly speaking, we should talk about the *mass* of the Earth and not its weight. The weight of an object is a function of the gravitational field the object is in. So if you are, say, 180 lbs on Earth on the Moon you would weight just 30 lbs. So in order to talk about the weight of the Earth we would have to know what gravitational field we're talking about. The mass of the Earth, however, is more or less a constant. We gain trivial amounts of mass from dust blown at us by the solar winds and we gain slightly more (but still trivial) amounts of mass from asteroid impacts (large ones actually cause us to lose mass).

Actually, the Earth IS slowing down but not because of its mass. Remember that any body in motion will continue in motion unless acted upon by another force. The Earth's rotation is slowing down but not because of OUR mass but because of the mass of the Moon. Some of the energy of Earth's rotation is transferred to the Moon. There is also friction from space dust.

It will take a few billion more years before a day on the planet gets appreciably longer though. :)

Cheers
Aj

Ok. I need to know. Is there a true scientific reason for the level of stupidity on Fox News?

http://www.huffingtonpost.com/2011/0..._n_817723.html