Dichotomy’s non-random science questions.

[swansont]

the Carbon Dioxide phase diagram is usually used as an introduction for this. it has reasonable variations with pressure and is very simple to follow.

 

Yes, it is nice and simple.

 

http://www.answers.com/topic/supercritical-drying (lower left side)

[Spyman]

Q21. Could two identical (size, weight) stars exist in the same solar system? Or, would they collide to form one star, or splinter to form smaller stars, planets, comets, etc?

A stellar system of two stars is known as a binary star, binary star system or physical double star. If there are no tidal effects, no perturbation from other forces, and no transfer of mass from one star to the other, such a system is stable, and both stars will trace out an elliptical orbit around the center of mass of the system indefinitely.

Examples of binary systems are Sirius, Procyon and Cygnus X-1, the last of which probably consists of a star and a black hole.

Most multiple star systems known are triple.

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

 

Anyone know if they decided on what a planet means yet?

A planet, as defined by the International Astronomical Union (IAU), is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, not massive enough to cause thermonuclear fusion in its core, and has cleared its neighbouring region of planetesimals.

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

[insane_alien]

Q21. Could two identical (size, weight) stars exist in the same solar system? Or, would they collide to form one star, or splinter to form smaller stars, planets, comets, etc?

 

while not identically massed stars the nearest starsystem to us (alpha centauri) is a triple star system. binary systems are common though it would be rare for the stars to be exactly the same weight, one is often bigger than the other.

[Mr Skeptic]

A planet, as defined by the International Astronomical Union (IAU), is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, not massive enough to cause thermonuclear fusion in its core, and has cleared its neighbouring region of planetesimals.

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

 

Thanks, Spyman. So they really did demote Pluto then. Wasn't sure they would do that. Now we only have 8 planets

[insane_alien]

well, they did kind of make an official announcement saying that they had demoted pluto. i can see where the confusion was.

[dichotomy]

while not identically massed stars the nearest starsystem to us (alpha centauri) is a triple star system. binary systems are common though it would be rare for the stars to be exactly the same weight, one is often bigger than the other.

 

I supppose what I'm getting at is if there where two identically massed stars within the one binary star system, and near enough to each other , then i'd think they could not orbit around each other. They'd have to collide, bounce, explode or something else wouldn't they? My basis for this assumption is that smaller objects must orbit larger ones in a solar system.

 

Q22. In theory, can water alone be pressurized to the point of being able to 'cut' diamond? I’d imagine in reality a harder than diamond material would be required for the nozzle of a water jet cutter.

The diamond nozzles used by water jets require periodic replacement due to water wearing them out, so logically this seems possible, in theory.

[Mr Skeptic]

I supppose what I'm getting at is if there where two identically massed stars within the one binary star system, and near enough to each other , then i'd think they could not orbit around each other. They'd have to collide, bounce, explode or something else wouldn't they? My basis for this assumption is that smaller objects must orbit larger ones in a solar system.

 

Why would they do that? The only reason you say the smaller object orbits the bigger one is because the bigger one moves less. The orbit is always about the center of mass, btw, and always consists of both objects falling toward each other and moving to the side so they don't collide.

 

Q22. In theory, can water alone be pressurized to the point of being able to 'cut' diamond? I’d imagine in reality a harder than diamond material would be required for the nozzle of a water jet cutter.

The diamond nozzles used by water jets require periodic replacement due to water wearing them out, so logically this seems possible, in theory.

 

I'd say so. You can cut with anything so long as you throw it hard enough...

[dichotomy]

Why would they do that? The only reason you say the smaller object orbits the bigger one is because the bigger one moves less. The orbit is always about the center of mass, btw, and always consists of both objects falling toward each other and moving to the side so they don't collide.

 

So , 2 identical stars could orbit each other, no matter how close they where?

[Mr Skeptic]

So , 2 identical stars could orbit each other, no matter how close they where?

 

Pretty much. Obviously not if their separation was not twice their radius.

 

At close distances, I think the tidal forces exerted on each other would cause the orbit to rapidly decay though.

[dichotomy]

At close distances, I think the tidal forces exerted on each other would cause the orbit to rapidly decay though.

 

Resulting in what? Two stars that just stop in space while everything nearby enough orbits them? Cheers.

[insane_alien]

Mr Skeptic is reffering to the roche limit. if the stars were closer than this then tidal forces would rip the stars appart and for a single merged star. it would be really awesome to watch but probably deadly from the amount of radiation.

 

if they are outside their particular roche limits(at all points in the orbit) then they will happily orbit the centre of mass of the system which will be a point in empty space.

[dichotomy]

Q23. Could black holes in space simply be new stars forming? Is there a theory relating to this?

 

Q24. Are black holes just mind bogglingly large, 'off the scales' space hurricanes?

[iNow]

Blackholes are old stars dying, so I'm not sure about the first idea there.

They come in different sizes, small, medium, large, and supermassive. The size is a function of how big the collapsed star was and how long it's been feeding.

[dichotomy]

Blackholes are old stars dying, so I'm not sure about the first idea there.

They come in different sizes, small, medium, large, and supermassive. The size is a function of how big the collapsed star was and how long it's been feeding.

 

 

Ok, then could they be stars reforming as smaller stars, or planets forming from scratch?

 

Are they proven to be collapsed stars? Or, is this speculation?

[Spyman]

Black Holes are not proven and have not been directly observed.

 

They are theoretical outcomes of the model "Relativity", which has so far passed every test made.

(Observations of very compact objects that seems to fit the description has been made though.)

 

According to Relativity nothing can escape a Black Hole -> they can't be reforming to anything else.

 

 

Stellar evolution is well observed and are not speculation.

 

The nuclear process inside the star is countering gravity, when the fuel is consumed gravity wins.

(Stars goes through several cycles with different fuels, depending on size.)

[iNow]

Black Holes are not proven and have not been directly observed.

I agree with most of your post, but definitely not the quote above. They are proven, and have been observed. Here's but a few examples:

 

http://chandra.harvard.edu/photo/category/blackholes.html

[Spyman]

I agree with most of your post, but definitely not the quote above. They are proven, and have been observed. Here's but a few examples:

 

http://chandra.harvard.edu/photo/category/blackholes.html

Observations of X-rays from accretion discs around unseen objects is not conclusive evidence.

 

Q: If light cannot escape black holes, how can we take pictures of them?

 

A: You are correct that light can't escape a black hole. What we can see in astronomical images is light from material that is heated up when it gets close to a black hole. This material can glow very brightly, especially in ultraviolet light and X-rays.

http://chandra.harvard.edu/resources/faq/black_hole/bhole-83.html

 

Q: In one of your pictures you explain that the bright lights are black holes. I have always been told that black holes cannot be seen. Could you please explain this to me?

 

A: No light of any kind, including X-rays, can escape from inside the event horizon of a black hole. The X-rays Chandra observes from the vicinity of black holes are from matter that is very close to the event horizon of black holes. Matter is heated to millions of degrees as it is pulled toward the black hole, so it glows in X-rays.

http://chandra.harvard.edu/resources/faq/black_hole/bhole-53.html

 

Astronomers have many candidate objects they think are probably black holes, on the basis of several kinds of evidence ... Their existence is nowadays taken for granted by young scientists, but it's important to realise than none have ever conclusively been found.

http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/black_holes.html

 

Before discussing black holes in detail we should acknowledge that the existence of such objects has still not been definitely established. There are undoubtedly bodies in the universe whose densities and gravitational intensities are extremely great, but the empirical evidence for actual black holes, although impressive, is still largely circumstantial and could conceivably have other explanations.

http://www.mathpages.com/rr/s7-03/7-03.htm

[iNow]

Point taken, Spyman, and I sense you are more literate on the topic than myself. However, I just see this line of reasoning a bit parallel to some arguments against evolution. We might not be able to "See" the transformation of a fish to an amphibian, but that doesn't mean that all evidence doesn't point to the merit of such a conclusion. Cignus X-1, here we come.

 

 

Who's this Chandrasekhar cat, and how dare he challenge Eddington!

[Spyman]

The evidence is piling up and is very impressive, in my personal opinion it is the most reasonable option.

 

But there is a slight chance that the 'amphibian' is a very different creature than we thought...

[dichotomy]

Thanks for post #67 SPYMAN. Good stuff.

[Fred56]

Ok, why are there only three "forms" it takes (solid-liquid-gas), ignoring BECs, supersolids and liquids, and plasmas for the time being?

[insane_alien]

because there isn't a homogenous intermediate form.

[Mr Skeptic]

Except for things like glass which as they cool smoothly transition from a somewhat viscous liquid to a liquid so viscous it seems solid. Or to a solid. I wasn't ever very clear on that.

[insane_alien]

no its definitely solid. just like ice. ice is another solid that will deform over time.

 

it is more correctly called an amorphous solid. granted the classification isn't as clear cut as most of them as it behaves very weirdly for a solid and ever weirder for a supercooled liquid. it does not however warrant a phase of it's own.

[dichotomy]

Q25. Does the earth weigh exactly the same as it did about a billion years ago? Do plant and animal growth/birth rates affect the weight of the earth?

 

I’d think the earth would weigh the same (with the exception of meteors striking the earth and adding to its weight, space craft etc, leaving the earth and decreasing its weight). E.g. I think of a human being that is born, it grows by consuming the nutrients of the earth, taking a weight from one place on earth and putting that weight into its body. There is no weight loss/gain to the earth that I can see in this scenario. Yes?