Isaac Arthur Videos Discussion(Sleeping Giants)

[DAL59]

1 hour ago, PB666 said:

Example colonizing rogue planets - yes its possible

It is possible, but I, and probably Isaac Arthur, would agree it would be difficult and impracticable.  Most of these videos are thought experiments.  

1 hour ago, PB666 said:

Where in the solar system do we find planet sized loads of carbon, in the middle of the sun?

Ironically, yes, in the middle of the sun.

 

[PB666]

Well, I tell you if we can get fusion to work we could also make a black hole, theoretically
If you had fusion in space, you manage to deplete neutrons of energy, spin them and then hold them by spin until you have enough to form exotic matter.
If you had fusion you could make iron in carbon (except those are made in the last dying moments of a star during core collapse)

If and if and if and if and if and if  . . . . . .

If you took hydrogen from the Sun just exactly where would you keep it? don't answer.

 

 

[DAL59]

Literally anywhere.  

[PB666]

2 minutes ago, DAL59 said:

Literally anywhere.  

OK, how about your house?

Please, lets dispense with the hand-waving stuff, everything takes energy, either M = E/c² and/or E. 

[DAL59]

3 minutes ago, PB666 said:

either M = E/c² and/or E. 

Exactly.  Some of the hydrogen is used as fuel to move the rest.  

[magnemoe]

5 hours ago, PB666 said:

Well, I tell you if we can get fusion to work we could also make a black hole, theoretically
If you had fusion in space, you manage to deplete neutrons of energy, spin them and then hold them by spin until you have enough to form exotic matter.
If you had fusion you could make iron in carbon (except those are made in the last dying moments of a star during core collapse)

If and if and if and if and if and if  . . . . . .

If you took hydrogen from the Sun just exactly where would you keep it? don't answer.

Last question is trivial compared to the previous ones. 
Making iron is probably not cost effective and we are unlikely to run out of iron. 

1 hour ago, DAL59 said:

Exactly.  Some of the hydrogen is used as fuel to move the rest.  

Now doing hydrogen fusion is hard, far harder than easy fusion who we an not do outside of hydrogen bombs, doing hydrogen fusion on particles passing trough the engine at relativistic speed is harder, compare an campfire and an scramjet. The campfire is the only of this technologies we have solved well enough   

[Guest]

6 hours ago, DAL59 said:

Most of these videos are thought experiments.

Don't. It doesn't matter, killjoys will be killjoys.

[PB666]

1 hour ago, magnemoe said:

Last question is trivial compared to the previous ones. 
Making iron is probably not cost effective and we are unlikely to run out of iron. 

Now doing hydrogen fusion is hard, far harder than easy fusion who we an not do outside of hydrogen bombs, doing hydrogen fusion on particles passing trough the engine at relativistic speed is harder, compare an campfire and an scramjet. The campfire is the only of this technologies we have solved well enough   

If you had the capability of doing a dyson sphere why not just create hydrogen bombs, create a large sphere, pull a vacuum on it, blow up a hydrogen bomb at the center, remove all the heat compress the remaining gas, repeat. Alas someone has come up with a viable source of nuclear energy in space, lol. You could put your steam transformer on the inside and the secondary radiators around the shell, and overtime you will have all the deuterium and tritium you need. IN fact you could just surround the bomb with about 100 meters of water, it would vaporize the water and you could just gate the steam through a tubine and collect the condensate on the other side of the radiator.

In fact you could just use all the nuclear bombs left over from the cold war take the war heads into space, detonate for a few months.

 

[DAL59]

8 hours ago, magnemoe said:

Now doing hydrogen fusion is hard

I was talking about nuclear rockets

Like nuclear gas core engines.  

[magnemoe]

12 hours ago, PB666 said:

If you had the capability of doing a dyson sphere why not just create hydrogen bombs, create a large sphere, pull a vacuum on it, blow up a hydrogen bomb at the center, remove all the heat compress the remaining gas, repeat. Alas someone has come up with a viable source of nuclear energy in space, lol. You could put your steam transformer on the inside and the secondary radiators around the shell, and overtime you will have all the deuterium and tritium you need. IN fact you could just surround the bomb with about 100 meters of water, it would vaporize the water and you could just gate the steam through a tubine and collect the condensate on the other side of the radiator.

In fact you could just use all the nuclear bombs left over from the cold war take the war heads into space, detonate for a few months.

 

Now this is easy, don't compare to dyson swarms at all, more in L5 class orbital habitats scale. 
It should work but see an normal nuclear reactor as more practical, both are heat engines after all. 

[PB666]

1 minute ago, magnemoe said:

Now this is easy, don't compare to dyson swarms at all, more in L5 class orbital habitats scale. 
It should work but see an normal nuclear reactor as more practical, both are heat engines after all. 

True, fission generates alot of deuterated water. What better to do with the water than make small H-bombs.

But yeah if you watch IA you would have a tendency to believe that scale of fusion would be easy, of course when you don't currently have 100t to LEO system that works. . .its impossible.

The argument this morning about RL10b-2 being used as a cricularization engine, yeah sure if you are dealing with a 15t payload, but to do any of the things we are talking about in this forum (lets say 80%) that payload is hideously small.

I consider the threshold for colonizing space is the ability to put a 1 kt payload into space. I would say assembling a fusion reactor in space as within the next 100 years, impossible.

 

[DAL59]

9 hours ago, PB666 said:

I consider the threshold for colonizing space is the ability to put a 1 kt payload into space.

Aldebaran reusable nuclear space plane:

[snip]

 

Edited December 12, 2017 by DAL59
Bad image link.

[PB666]

4 hours ago, DAL59 said:

Aldebaran reusable nuclear space plane:

data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD/2wCEAAkGBxMTEhUTExMW . . . . 6pJqfmJURud6woUPHJvZcoJaP//Z

 

Nice jibberish>

[DAL59]

Just now, PB666 said:

Nice jibberish>

Umm... @Vanamonde @Deddryk, how do I avoid this.  

[PB666]

1 minute ago, DAL59 said:

Umm... @Vanamonde @Deddryk, how do I avoid this.  

YOu have to download the image to Imgur and then cut and paste the png file link.

Edited December 12, 2017 by PB666

[Vanamonde]

Probably what PB666 said, but where is the image? 

[DAL59]

@Vanamonde Is it fixed now?

[PB666]

24 minutes ago, DAL59 said:

@Vanamonde Is it fixed now?

yep.

[DAL59]

 

[DAL59]

 

[DAL59]

 

[wumpus]

On 12/10/2017 at 11:07 AM, PB666 said:

The guy does a fairly good job of burying the logical flaws in his arguments but over time they begin to pop out, I watched many of his videos.

3. This is actually 2b. but its so big. There is the basic opinion, for example raising an object from the Surface of the Earth to GSO or LEO cost much  less than a rocket. NO!!!!!, it costs in energy nearly as much, the only difference is that a rocket launches  loses about 10% of its energy due to gravity effects and drag.

Most of your arguments are pretty good, but this one misses the point entirely.  A rocket has to obey the rocket equation (and all the tyranny that implies) while an elevator/climber does not.  Unless your rocket has an em-drive (or equally absurd high-Isp engine), it won't get close to the elevator's efficiency thanks to the need to accelerate/lift its own fuel along with the payload.  The "railgun to orbit" is obviously trying to do this as well, but there are so many issues with this that to pick apart a single problem (like evacuating the air) is to miss all the other reasons it wouldn't work.

Don't forget that SpaceX justifies the cost of a BFR over 1000 launches: expect orbital launch R&D to come to a sudden halt at spacex after building one of these beasts as they need to recoup the costs over so many launches.  Even so, I expect that this type of handwaving is optimizing against costs that won't be long pole in the next century (or whenever this is supposed to happen).

* My preferred "railgun to orbit" would accelerate a ramjet (preferably scramjet) on a rail until it could power itself.  The ramjet stage would then accelerate to "maximum velocity" (probably mach 4 for the ramjet, mach 6-8 for the scramjet) and then switch to a hydrolox rocket.  This whole very silly rocket would presumably be simplified to an air-augmented recoverable first stage and standard second stage (presumably much like a falcon/BFR/New Glen, only with air augmentation).  It might be possible to justify the R&D for the air augmentation (especially for something like the BFR where the fuel eventually creeps into the visible costs), but I can't see the "railgun" method ever justifying the costs.

[DAL59]

 

[DAL59]

 

[tater]

Haven’t watched it, but there is no place to go in space, except places we build ourselves. Evacuation requires a destination, and any such destination would require more planning and effort to build than the actual evacuation by orders of magnitude.