Can we now build the "space tower"?

On Dec 16, 7:14 pm, Michael Ash wrote:
In rec.arts.sf.science BradGuth wrote:


On Dec 16, 12:37 pm, Michael Ash wrote:
In rec.arts.sf.science Brian Davis wrote:
On Dec 15, 8:20?pm, Yousuf Khan wrote:

At around 10-15 km up, they will be contending against
the Jet Stream, sometimes reaching upto 400 km/h.

I always find it humorous that when talking about very tall, space-
elevator-style constructions, the terrifying jet stream always seems
to pop up. For a structure in compression 150 km high, any minor force
exerted by the wind below 10 km is literally going to be like a high-
velocity wind directed at my ankles: locally something to be concerned
about, but not a factor for the tower. And for tensional
(conventional) space elevators, it's even sillier: you build them at
the equator, and their minimum cross-section is down in the "turbulent
ten" lowest kilometers. Besides which, there is no jet stream at the
equator. Sigh... invoking non-applicable threats into situations where
they wouldn't matter much anyway really doesn't inspire confidence in
the line of reasoning.

I think people also forget about the effect of atmospheric density. Jet
streams are fast but they aren't all *that* strong. They're very high and
therefore are in very thin air, which substantially reduces the force that
they will impart to anything they encounter.

Typical skyscrapers are built to withstand hurricane-force winds, which
happen at sea level and are therefore more forceful. Those winds also act
along the entire height of the skyscraper instead of just some small
portion, which as you point out makes them even less significant.

Spooks, moles and MIB of the mainstream status quo have license to
kill.

That's, er, fascinating, but what's it got to do with jet streams or space
towers or, well, *anything*?

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

A space tower or much less my LSE-CM/ISS doesn't fit into that box of
yours, does it.

If some outsider is rocking that mainstream boat, the first thing
folks tend to do is send in the clowns, and if that doesn't work they
release those pesky MIB.

~ BG

On Dec 16, 5:44 pm, john griffin wrote:
BradGuth wrote:
Spooks, moles and MIB of the mainstream status quo have
license to kill.

Now that you gave up the secret, you have to kill everybody.
Turkey.

Trust me, it's no secret.

~ BG

On Dec 16, 10:01 pm, Erik Max Francis wrote:
Yousuf Khan wrote:
There is no reason why anyone should worship this worthless shiny stone.
This stone whose most useful purpose is as a material for cutting and
abrading equipment.

So it's not worthless, then?

Diamond is not anymore or less worthless than gravel is, until you mix
gravel into concrete. Or sand is worthless until you melt it into
computer chip wafers. But diamond as simply a pretty thing to wear?
Worthless.

Until we can find ways of harnessing degenerate
matter from dwarf stars or neutron stars, it's our hardest known material.

Since as you say such matter is degenerate, that means that it isn't
harnessable. White dwarf and neutron star matter is not stable in
substellar lumps.

Sure, that's why I said "until" which has an implied "if" in there.
Anyways, I can see even unstable degenerate matter as useful, if only
as concentrated explosives that can blow a hole through any normal
matter. This stuff should pack more energy than either nuclear fission
or fusion, but less than matter-antimatter reactions.

Yousuf Khan

YKhan wrote:

On Dec 16, 10:01 pm, Erik Max Francis wrote:
Yousuf Khan wrote:
There is no reason why anyone should worship this worthless shiny stone.
This stone whose most useful purpose is as a material for cutting and
abrading equipment.
So it's not worthless, then?

Diamond is not anymore or less worthless than gravel is, until you mix
gravel into concrete. Or sand is worthless until you melt it into
computer chip wafers. But diamond as simply a pretty thing to wear?
Worthless.

Value is what people are willing to pay for it. Welcome to economics 101.

Sure, that's why I said "until" which has an implied "if" in there.
Anyways, I can see even unstable degenerate matter as useful, if only
as concentrated explosives that can blow a hole through any normal
matter. This stuff should pack more energy than either nuclear fission
or fusion, but less than matter-antimatter reactions.

Now you're talking about something else; earlier you said they would
"hard." Degenerate matter has no "hardness." It's dense because there
is a huge amount of mass compacting it into a degenerate state. That
mass doesn't give it hardness, it just makes it dense. Hardness and
density are not the same thing.

--
Erik Max Francis && && http://www.alcyone.com/max/
San Jose, CA, USA && 37 18 N 121 57 W && AIM, Y!M erikmaxfrancis
Triumph cannot help being cruel.
-- Jose Ortega y Gasset

Brian Davis skreiv:

I always find it humorous that when talking about very tall, space-
elevator-style constructions, the terrifying jet stream always seems
to pop up. For a structure in compression 150 km high, any minor force
exerted by the wind below 10 km is literally going to be like a high-
velocity wind directed at my ankles: locally something to be concerned
about, but not a factor for the tower.

It's sillier than that even. Because wind-load scales proportionally to
diameter, more or less, this means larger structures are less influenced
by wind than small structures.

If you make a tower that is 10 times as large in every direction, then
the wind-load is also (on the order of) 10 times as large, (assuming the
wind only hits the lower X kilometres of it) however the cross-section,
influencing strength and stiffness, is 100 times as large.

We're talking a tower that is 10kmx10km on the lower part here, it's
gigantic. I'm fairly sure wind-load is completely down in the noise for
such a structure.


Eivind

Yousuf Khan wrote:

Diamonds are already a commodity, except we
weren't allowed to know.

There is no reason why anyone should worship this worthless shiny stone.
This stone whose most useful purpose is as a material for cutting and
abrading equipment. Until we can find ways of harnessing degenerate
matter from dwarf stars or neutron stars, it's our hardest known material.

*wrong* google Rhenium Diboride, its *HARDER* ;-)

Erik Max Francis wrote:

:YKhan wrote:
:
: Sure, that's why I said "until" which has an implied "if" in there.
: Anyways, I can see even unstable degenerate matter as useful, if only
: as concentrated explosives that can blow a hole through any normal
: matter. This stuff should pack more energy than either nuclear fission
: or fusion, but less than matter-antimatter reactions.
:
:Now you're talking about something else; earlier you said they would
:"hard." Degenerate matter has no "hardness." It's dense because there
:is a huge amount of mass compacting it into a degenerate state. That
:mass doesn't give it hardness, it just makes it dense. Hardness and
:density are not the same thing.
:

For an every day example of this, look at lead (or gold). Both quite
dense. Both quite soft.


--
"Ignorance is preferable to error, and he is less remote from the
truth who believes nothing than he who believes what is wrong."
-- Thomas Jefferson

On Dec 17, 1:25 am, Eivind wrote:
Brian Davis skreiv:

I always find it humorous that when talking about very tall, space-
elevator-style constructions, the terrifying jet stream always seems
to pop up. For a structure in compression 150 km high, any minor force
exerted by the wind below 10 km is literally going to be like a high-
velocity wind directed at my ankles: locally something to be concerned
about, but not a factor for the tower.

It's sillier than that even. Because wind-load scales proportionally to
diameter, more or less, this means larger structures are less influenced
by wind than small structures.

If you make a tower that is 10 times as large in every direction, then
the wind-load is also (on the order of) 10 times as large, (assuming the
wind only hits the lower X kilometres of it) however the cross-section,
influencing strength and stiffness, is 100 times as large.

We're talking a tower that is 10kmx10km on the lower part here, it's
gigantic. I'm fairly sure wind-load is completely down in the noise for
such a structure.

Eivind

Correct. as like a mountain, it'll create it's own weather.

~ BG

In rec.arts.sf.science BradGuth wrote:
On Dec 16, 7:14 pm, Michael Ash wrote:
In rec.arts.sf.science BradGuth wrote:


On Dec 16, 12:37 pm, Michael Ash wrote:
In rec.arts.sf.science Brian Davis wrote:
On Dec 15, 8:20?pm, Yousuf Khan wrote:

At around 10-15 km up, they will be contending against
the Jet Stream, sometimes reaching upto 400 km/h.

I always find it humorous that when talking about very tall, space-
elevator-style constructions, the terrifying jet stream always seems
to pop up. For a structure in compression 150 km high, any minor force
exerted by the wind below 10 km is literally going to be like a high-
velocity wind directed at my ankles: locally something to be concerned
about, but not a factor for the tower. And for tensional
(conventional) space elevators, it's even sillier: you build them at
the equator, and their minimum cross-section is down in the "turbulent
ten" lowest kilometers. Besides which, there is no jet stream at the
equator. Sigh... invoking non-applicable threats into situations where
they wouldn't matter much anyway really doesn't inspire confidence in
the line of reasoning.

I think people also forget about the effect of atmospheric density. Jet
streams are fast but they aren't all *that* strong. They're very high and
therefore are in very thin air, which substantially reduces the force that
they will impart to anything they encounter.

Typical skyscrapers are built to withstand hurricane-force winds, which
happen at sea level and are therefore more forceful. Those winds also act
along the entire height of the skyscraper instead of just some small
portion, which as you point out makes them even less significant.

Spooks, moles and MIB of the mainstream status quo have license to
kill.

That's, er, fascinating, but what's it got to do with jet streams or space
towers or, well, *anything*?

A space tower or much less my LSE-CM/ISS doesn't fit into that box of
yours, does it.

If some outsider is rocking that mainstream boat, the first thing
folks tend to do is send in the clowns, and if that doesn't work they
release those pesky MIB.

Oh I get it, you think I sent the spooks after you to shut you up!

How quaint? Don't you crazy people ever come up with anything *new*?

By the way, while you're being crazy, do you think you could stop quoting
my signature? It looks silly and serves no useful purpose.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

On Mon, 08 Dec 2008 21:26:26 +0000, Martha Adams wrote:

"Puppet_Sock" wrote in message
news:bbd4e190-
...
On Dec 8, 12:44 pm, Robert Clark wrote: [snip]
Artificial diamonds - now available in extra large. 18:11 13 November
2008 by Catherine Brahic. "A team in the US has brought the world one
step closer to cheap, mass-
produced, perfect diamonds. The improvement also means there is no
theoretical limit on the size of diamonds that can be grown in the lab.
[snap]

While that's quite interesting, there's a huge gap between big cheap
diamond crystals and an orbital tower.

I'm not even sure diamonds are strong enough. IIRC, they fall short
quite a bit.
Socks

While diamonds are hard, they are also brittle. Given the stresses that
a beanstalk would be subject to, I suspect that accumulated micro-
fractures would soon break a diamond cable.

--
John F. Eldredge --
PGP key available from http://pgp.mit.edu
"Reserve your right to think, for even to think wrongly is better
than not to think at all." -- Hypatia of Alexandria