Author Topic: Space and astronomy  (Read 17465 times)

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Ian

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Space and astronomy
« on: September 13, 2010, 07:24:42 PM »
Twinkling in the sky is a diamond star of 10 billion trillion trillion carats, astronomers have discovered.
The cosmic diamond is a chunk of crystallised carbon, 4,000 km across, some 50 light-years from the Earth in the constellation Centaurus.

It's the compressed heart of an old star that was once bright like our Sun but has since faded and shrunk. Astronomers have decided to call the star "Lucy" after the Beatles song, Lucy in the Sky with Diamonds.
"You would need a jeweller's loupe the size of the Sun to grade this diamond," says astronomer Travis Metcalfe, of the Harvard-Smithsonian Center for Astrophysics, who led the team of researchers that discovered it.

The diamond star completely outclasses the largest diamond on Earth, the 546-carat Golden Jubilee which was cut from a stone brought out of the Premier mine in South Africa. The huge cosmic diamond - technically known as BPM 37093 - is actually a crystallised white dwarf. A white dwarf is the hot core of a star, left over after the star uses up its nuclear fuel and dies. It is made mostly of carbon. For more than four decades, astronomers have thought that the interiors of white dwarfs crystallised, but obtaining direct evidence became possible only recently. The white dwarf is not only radiant but also rings like a gigantic gong, undergoing constant pulsations.

"By measuring those pulsations, we were able to study the hidden interior of the white dwarf, just like seismograph measurements of earthquakes allow geologists to study the interior of the Earth. We figured out that the carbon interior of this white dwarf has solidified to form the galaxy's largest diamond," says Metcalfe.

Astronomers expect our Sun will become a white dwarf when it dies 5 billion years from now. Some two billion years after that, the Sun's ember core will crystallise as well, leaving a giant diamond in the centre of the solar system.

"Our Sun will become a diamond that truly is forever," says Metcalfe.
“Nothing is so firmly believed as that which we least know.”   ― Michel de Montaigne

Si hoc legere scis, nimis eruditionis habes.

Ian

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Re: Space and astronomy
« Reply #1 on: November 17, 2010, 03:57:41 PM »
AT A news conference before his first experience of weightlessness in 2007, theoretical physicist Stephen Hawking said that he hoped his zero-gravity flight would encourage public interest in space exploration. He argued that with an ever-increasing risk of wiping ourselves out on Earth, humans would need to colonise space.

Hawking has since argued that we must do this within two centuries or else face extinction. He was no doubt encouraged by US President Barack Obama's announcement in April this year of a new initiative to send people to Mars by 2030.

Hawking, Obama and other proponents of long-term space travel are making a grave error. Humans cannot leave Earth for the several years that it takes to travel to Mars and back, for the simple reason that our biology is intimately connected to Earth.

To function properly, we need gravity. Without it, the environment is less demanding on the human body in several ways, and this shows upon the return to Earth. Remember the sight of weakened astronauts emerging after the Apollo missions? That is as nothing compared with what would happen to astronauts returning from Mars.

One of the first things to be affected is the heart, which shrinks by as much as a quarter after just one week in orbit (The New England Journal of Medicine, vol 358, p 1370). Heart atrophy leads to decreases in blood pressure and the amount of blood pushed out by the heart. In this way heart atrophy leads to reduced exercise capacity. Astronauts returning to Earth after several months in the International Space Station experience dizziness and blackouts because blood does not reach their brains in sufficient quantities.

Six weeks in bed leads to about as much atrophy of the heart as one week in space, suggesting that the atrophy is caused by both weightlessness and the concomitant reduction in exercise.

Other muscle tissue suffers too. The effects of weightlessness on the muscles of the limbs are easy to verify experimentally. Because they bear the body's weight, the "anti-gravity" muscles of the thighs and calves degenerate significantly when they are made redundant during space flight.

Despite the best attempts to give replacement exercise to crew members on the International Space Station, after six months they had still lost 13 per cent of their calf muscle volume and 32 per cent of the maximum power that their leg muscles could deliver (Journal of Applied Physiology, vol 106, p 1159).

Various metabolic changes also occur, including a decreased capacity for fat oxidation, which can lead to the build-up of fat in atrophied muscle. Space travellers also suffer deterioration of immune function both during and after their missions (Aviation, Space, and Environmental Medicine, vol 79, p 835).

Arguably the most fearsome effect on bodies is bone loss (The Lancet, vol 355, p 1569). Although the hardness and strength of bone, and the relative ease with which it fossilises, give it an appearance of permanence, bone is actually a living and remarkably flexible tissue. In the late 19th century, the German anatomist Julius Wolff discovered that bones adjust to the loads that they are placed under. A decrease in load leads to the loss of bone material, while an increase leads to thicker bone.

It is no surprise, then, that in the microgravity of space bones demineralise, especially those which normally bear the greatest load. Cosmonauts who spent half a year in space lost up to a quarter of the material in their shin bones, despite intensive exercise (The Lancet, vol 355, p 1607). Although experiments on chicken embryos on the International Space Station have established that bone formation does continue in microgravity, formation rates are overtaken by bone loss.

What is of greatest concern here is that, unlike muscle loss which levels off with time, bone loss seems to continue at a steady rate of 1 to 2 per cent for every month of weightlessness. During a three-year mission to Mars, space travellers could lose around 50 per cent of their bone material, which would make it extremely difficult to return to Earth and its gravitational forces. Bone loss during space travel certainly brings home the maxim "use it or lose it".
“Nothing is so firmly believed as that which we least know.”   ― Michel de Montaigne

Si hoc legere scis, nimis eruditionis habes.

Paddy

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Re: Space and astronomy
« Reply #2 on: November 17, 2010, 07:24:15 PM »
The proposed Mars mission is being dubbed "The Mars 500" as the round trip will take 500 days. I'm sure they must have plans in place to deal with the problems you mention. Or at least I would hope so!

Fester

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Re: Space and astronomy
« Reply #3 on: November 17, 2010, 07:40:31 PM »
In order to colonise space then, it seems that it would be necessary to accelerate evolution to a stage where humans are shapeless blobs, without bones or muscle.
In this respect I would like to put myself forward as I am truly ahead of my time in term of the necessary physique.

A couple more visits to Fat Cat or MacDonalds and I think I'm nearly ready!


Fester...
- Semper in Excretum, Sole Profundum Variat -

Pendragon

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Re: Space and astronomy
« Reply #4 on: November 17, 2010, 08:26:27 PM »
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In order to colonise space then, it seems that it would be necessary to accelerate evolution to a stage where humans are shapeless blobs, without bones or muscle.
Looks like you'll come second to the Americans Fester   _))*
Only hindsight has 20/20 vision
Angiegram - A romantic notion derived from the more mundane truth.

Truth is, everybody is going to hurt you; you just gotta find the ones worth suffering for." -Bob Marley

Yorkie

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Re: Space and astronomy
« Reply #5 on: November 18, 2010, 09:07:16 AM »
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A couple more visits to Fat Cat or MacDonalds and I think I'm nearly ready!

All you need to do now is pump yourself full of Helium and let go this soil of your birth!     )*)&

Ian

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Re: Space and astronomy
« Reply #6 on: November 18, 2010, 08:47:14 PM »
They're going to  have to come up with centripetal-system space craft; that way the gravity can be maintained for long journeys. I also think that wormholes will probably become the travel method of choice as soon as we discover one and learn how to use it.
“Nothing is so firmly believed as that which we least know.”   ― Michel de Montaigne

Si hoc legere scis, nimis eruditionis habes.



DaveR

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Re: Space and astronomy
« Reply #7 on: November 18, 2010, 08:57:28 PM »
Is Space infinite? Views required.

Yorkie

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Re: Space and astronomy
« Reply #8 on: November 18, 2010, 09:10:37 PM »
Space must be infinite as everything requires space to exist.    So wherever something is there must be space.    $eu

Fester

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Re: Space and astronomy
« Reply #9 on: November 19, 2010, 12:22:03 AM »
Space must be infinite, because if it ended... then how could it end? .. a red-brick wall? .... and if so, whats behind that?

Not only is space infinite, but so is time... (backwards and forwards)...

Also, so is size.   (upwards and downwards) By that I mean, once you find the smallest building blocks of matter... even they must be made of something smaller....

This topic is too much for the human mind to cope with....
Fester...
- Semper in Excretum, Sole Profundum Variat -

Ian

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Re: Space and astronomy
« Reply #10 on: November 19, 2010, 07:59:45 AM »
Einstein argued it wasn't. Infinite, that is. And he calculated its circumference.  The analogy is a sphere;  like space, it has no beginning and no end point, but it isn't infinite. 
« Last Edit: November 19, 2010, 08:05:02 AM by Ian »
“Nothing is so firmly believed as that which we least know.”   ― Michel de Montaigne

Si hoc legere scis, nimis eruditionis habes.

Michael

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Re: Space and astronomy
« Reply #11 on: November 19, 2010, 07:37:43 PM »
I feel I should contribute to this discussion. But, my contribution needs readers to be HIGHLY intelegent to understand my theory. So, I'm going to the "Follow On" thread.  Could someone explain to me how the hell I play that----its too complicated for me.

Yorkie

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Re: Space and astronomy
« Reply #12 on: November 19, 2010, 07:54:45 PM »
Quite easy.  You use the last few letters (in the order they are in) to start a new word which does not have to be connected with the previous.

So,    glove  -  overcome   - mellow   - lowest   -   storm   - orme   etc etc

Fester

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Re: Space and astronomy
« Reply #13 on: November 20, 2010, 12:46:51 AM »
Oooh, methinks that the venerable Mike know this!

I expect he had his tongue firmly planted in his cheek when he wrote that... ZXZ
Fester...
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Fester

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Re: Space and astronomy
« Reply #14 on: November 20, 2010, 12:59:11 AM »
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Einstein argued it wasn't. Infinite, that is. And he calculated its circumference.  The analogy is a sphere;  like space, it has no beginning and no end point, but it isn't infinite. 

A sphere is by definition finite.... not in its circumference, but in its third dimensions.
I mean, there is an inside...(the universe?) and an outside...(where the extent of the sphere is reached) ... so, the question remains, if the universe is a sphere, then what is outside the sphere?

I always knew Einstein wasn't so bright, after all he couldn't even get a decent haircut and shave!
Fester...
- Semper in Excretum, Sole Profundum Variat -