[Bored chemist]

Gentlemen ,
The thrust of the thread is the quest for near-future spaceship architectures .I stated the question as I did because we don't have real spaceships yet , and will not without major conceptual and technological advances .  This is what I am questing for .
P.M. 

Then why waste everyone's time with nonsensical distractions like this?

This light expends much of it's stored energy impacting the surface , not heating it . This could concievably produce thrust above 1Mlb , depending upon the  efficiency of the "Heavy Light" conversion

[Professor Mega-Mind (OP)]

One of many POSSIBILITIES , all of which could yield miraculous results .  So hard to predict the development of technology .
P.M.

[Bored chemist]

One of many POSSIBILITIES , all of which could yield miraculous results .  So hard to predict the development of technology .
P.M.

Except that many things you talk about are IMPOSSIBILITIES.
Why can't you grasp that?

[Professor Mega-Mind (OP)]

There are ways to siphon energy from EMR in flight , so I definitely say "possible".

[Bored chemist]

, so I definitely say "possible".

You may say it, but that doesn't stop it being wrong.

[Professor Mega-Mind (OP)]

You are missing the trick !
While it is true that EMR sucks for recoil and impact involving bulk materials , you can transfer much of it's kinetic energy to intermediary electrons in flight . Each high-energy x-ray carries a kinetic-energy of almost 3-M.e-v . These little bb.s will hit a reciever with ~ 2.5-M.e-v of kinetic-energy , ALL AT ONCE ; far harder than the emitted light would have .  The challenge is developing an efficient electron-catching and recycling mechanism .  Such a device is analogous to a wave generator plunging up and down to drive a cork forward .  Analyse some Compton Scattering events for energy transfer , electrons are surprisingly good at changing EMR sine waves into lateral velocity .  The technical challenge is an efficient electron-catching device .  I suspect that the most efficient approach is to use concentrated waves , ergo the name " EMR Shockwave Engine " .  Go ahead , spew out your " It can't be ! " arguments , I actually nailed down this paradigm years ago ! 
Chuckling P.M.
__________________________________
*Discussion on Reactionless Drive
www.thenakedscientists.com/forum/index.php?topic=75493.new;topicseen#new 

[Kryptid]

These little bb.s will hit a reciever far harder than the emitted light would have . 

How? The photons can't donate more momentum to the electrons than they already have.

The challenge is developing an efficient electron-catching and recycling mechanism . 

Have you already forgotten when I pointed out that such a system would hold itself back and keep the engine from going anywhere?

[Professor Mega-Mind (OP)]

There is your fundamental error .  The recoil/impact of the light beam is nothing compared to it's energy content .  The electrons parasitise much of that hidden energy , turning it into kinetic energy instead of thermal energy .  On impact , they will push the reciever much harder than a light beam .
Remember , a gigawatt can power several jumbo jets at once .  That measly 1lb of thrust is nothing !
P.M.

[Kryptid]

There is your fundamental error .  The recoil/impact of the light beam is nothing compared to it's energy content .  The electrons parasitise much of that hidden energy , turning it into kinetic energy instead of thermal energy .  On impact , they will push the reciever much harder than a light beam .
Remember , a gigawatt can power several jumbo jets at once .  That measly 1lb of thrust is nothing !
P.M.

In principle, you can extract more momentum from a beam of light if you allow for multiple bounces. I've read about solar sail schemes where a laser is reflected multiple times between the sail and some reflector placed some distance away (not connected to the ship itself, obviously). Every time the light beam bounces between the two, it pushes both the ship and the reflector more and more strongly in opposite directions. If you tuned things right, you might be able to take advantage of that same idea by bouncing a laser beam multiple times back and forth between the inside of the engine and the cloud of electrons (although I would suggest a plasma, as it would be electrically neutral and therefore much easier to contain).

However, all of that boils down to how fast you can make those electrons (or plasma) move. There are probably more efficient schemes for that than pushing on it with a laser beam. Electromagnetic acceleration like that used in ion engines might work better.

[Professor Mega-Mind (OP)]

You go , Sum Dum Goy !
Extreme reaction engines have a potential !
P.M.

[Bored chemist]

Go ahead , spew out your " It can't be ! " arguments , I actually nailed down this paradigm years ago ! 

It wouldn't work years ago.
It still doesn't.
The reason was sorted out long before you were born.
https://en.wikipedia.org/wiki/Noether%27s_theorem

[Professor Mega-Mind (OP)]

If one accepts that a relativistic electron hits a reciever much harder than a same-energy photon , I yam in business !
P.

[Bored chemist]

If one accepts that a relativistic electron hits a reciever much harder than a same-energy photon , I yam in business !
P.

No.
You need to recognise that momentum and energy are both important and, if you want to do anything efficiently, you need to conserve energy as well as possible.

[Professor Mega-Mind (OP)]

Efficiency can be sacrificed for power , especially if you're running off of a nuclear reactor . 
Just for grins , what happens when a powerful wave of X-rays hits a closed container of plasma ? Come on , all together now !
P.M.

[Bored chemist]

Just for grins , what happens when a powerful wave of X-rays hits a closed container of plasma ? Come on , all together now !

It bounces off the container (by the definition of "closed"- you can't get into it).

[Professor Mega-Mind (OP)]

..........Unspeakably Obtuse !
I definitely meant a container made of X-ray transparent material .
P.

[Bored chemist]

..........Unspeakably Obtuse !
I definitely meant a container made of X-ray transparent material .
P.

Then you should have said so, rather than saying it was opaque.
Never mind...
If you stopped creating multiple threads about the same nonsense you would realise that I already answered this "point" here
https://www.thenakedscientists.com/forum/index.php?topic=75294.msg560838#msg560838

[Professor Mega-Mind (OP)]

I want each thread to concentrate on it's topic , but folks keep wandering !
P.

[guest39538]

If any of you have designs  , do not tell them on science  forums,  you  are just  a  ''dog''  to them , they will just take your ideas.

[Professor Mega-Mind (OP)]

You have a point , Mr. Box . 
However , what if I'm hit by a truck tomorrow ?  Millions of cancer patients scream to death unnecessarily , or humanity loses it's only reactionless drive , or a thousand timeless questions go unanswered ?  Don't I have a moral obligation to humanity here ?
P.M.