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1 hour ago, KG3 said:

Explosive bolts...

...a technician with a torque wrench very carefully tightening a nut, hoping he doesn't loose any fingers!

He shoots.

Spoiler

crossbow.jpg?1385678036ea86e3be1c21488702ffef1e924f87f1.jpg

 

P.S,
https://www.reddit.com/r/space/comments/57ux0w/space_shuttle_hold_down_post_nuts_that_are_split/

https://www.practicalmachinist.com/vb/antique-machinery-and-history/pyrotechnic-fasteners-part-one-313929/

Edited by kerbiloid
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4 hours ago, KG3 said:

Are they anything like the bolts I might see at a hardware store?

In a way. Certain non-space-grade designs use blank shotgun cartridges or somesuch to pop the bolt.

 

Edited by DDE
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20 hours ago, DDE said:

In a way. Certain non-space-grade designs use blank shotgun cartridges or somesuch to pop the bolt.

 

Where is this used?

Pyrotechnic fasteners are used on fighter jets to release drop tanks or larger bombs / rockets. 

Know that some cranes on oil platforms has an pyrotechnic wire cutter who cut the wire if the crane is about to tip over. Its an risk that the wire or cargo get stuck on an boat while unloading. 

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11 hours ago, said:

Is dark matter regular matter just moving backwards in time :0.0:

Welcome to the forums!

Dark matter is still a mystery.

We know very few things about it.

We know that it has mass and that it exerts a gravitational field based on its mass, the same way normal matter does.

But it does not interact with normal matter in any other way (that we currently know of.)

It is invisible, EM radiation is not impeded by it in any way. You cant touch it, it passes through normal matter, and vice versa, completely without resistance.

There is dark matter in the room with you now, although it is very diffuse. There is estimated to be approximately 1 protons-worth of mass of dark matter per 2-3 cm3, within our solar system.

 

One interesting hypothesis (note - unproven/lack of data, competes with other hypotheses) is that dark matter is normal matter that exists in other universes. Some advanced physics concepts describe how fields (eg: magnetic, electric) cannot pass between, or influence at all, other universes - except for gravity, which may be able to be felt across universes, and this is how we are detecting "dark matter". This would explain many of its strange properties, for example that you cannot see or touch it.

 

**edit**

Further note - if gravity can propagate across universes, this opens up the possibility of communication with other universes...

 

**edit#2**

Furtherfurther note - the "leaking" of gravity between universes has also been postulated to explain why gravity is so weak, compared to the other universal forces (eg: electromagnetism).

Edited by p1t1o
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3 hours ago, p1t1o said:

(dark matter)
We know that it has mass and that it exerts a gravitational field based on its mass, the same way normal matter does.

As we can see that the gravitational field (usually based on some mass) is exerted, we presume that there is some kind of matter gravitationally acting like a normal mass, lol.

3 hours ago, p1t1o said:

if gravity can propagate across universes, this opens up the possibility of communication with other universes...

And this really inspires!

Spoiler

warpstorm_by_kotnonekot-d7znbrl.jpg

 

Edited by kerbiloid
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On 2/7/2019 at 11:24 PM, <Joseph kerman> said:

Is dark matter regular matter just moving backwards in time :0.0:

Antimatter fits [all?] the equations as if it was running backwards in time, but I believe enough antimatter has been observed to show it increases in entropy (the one bit of physics that definitely shows the direction of time).

There's little reason to believe that dark matter would be anything like that.

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On 2/9/2019 at 5:44 PM, wumpus said:

Antimatter fits [all?] the equations as if it was running backwards in time, but I believe enough antimatter has been observed to show it increases in entropy (the one bit of physics that definitely shows the direction of time).

There's little reason to believe that dark matter would be anything like that.

Antimatter is not dark matter, one of the key features with dark matter is that it interact very little with normal matter outside of gravity. 
The remarkable thing with antimatter is how violently it react to normal matter :)

Something like neutrinos fit better, no don't thin normal neutrinos will work but they are an good template. 

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(Paging @ProtoJeb21)

I'm working on a very simple model for the atmosphere of an exoplanet, and I'm a bit stuck. I understand that it is possible to find scale height and the composition of an exoplanet's atmosphere. It should be possible to roughly find the planet's average temperature from the parent star's irradiance at the distance of the exoplanet. Is it possible to get an absolute value for density or pressure at an altitude from direct observation and thus create a rudimentary atmospheric model? (Assuming a very simplistic single layer atmosphere).

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Oxygen flows through the rubber pipes and inflates rubber chambers applying to the parts of body the required pressure.
The chambers inflate/deflate, fibers around the parts of body strangle/unstrangle.

Spoiler

0296943740.gif0245733138.gif

The pressure compensates the attempts of the blood to offset due to the accelerations, and the low pressure in case of the cabin decompression.

(The suit is attached to the breath system of the seat and cabin)

Edited by kerbiloid
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