[Jaaanosik (OP)]

Hi All,
Would it be possible to built an inertial propulsion system for a spaceship?
Inertial meaning that nothing is ejected from the spaceship and the spaceship is not interacting with any outside fields.
Energy would be used only on moving something/anything inside of the spaceship to generate an acceleration.
Is it doable?
Jano

[Kryptid]

That would violate conservation of momentum, so I'm going to say no.

[Janus]

I'm with Kryptid. No.

[Jaaanosik (OP)]

Come on guys, why so serious
So many views and only two opinions?
Jano

[Kryptid]

Come on guys, why so serious
So many views and only two opinions?
Jano

Opinions can't change the laws of physics.

[evan_au]

For a third opinion, see: https://www.thenakedscientists.com/forum/index.php?topic=79146.msg598377#msg598377

[Jaaanosik (OP)]

For a third opinion, see: https://www.thenakedscientists.com/forum/index.php?topic=79146.msg598377#msg598377

Yes,
I've seen that. That's the reason I said no interaction with outside fields.
Just something happening inside the ship itself,
Jano

[Jaaanosik (OP)]

Come on guys, why so serious
So many views and only two opinions?
Jano

Opinions can't change the laws of physics.

Kryptid,
the solution does not change the laws of physics.
It strives in them!
We'll have a vote if works at the end.

All,
Imagine you are a broker in Las Vegas.
What odds you would give me that I can present something that moves the ship ahead?
100:1?
1000:1?
Come on guys, this is for entertainment in this tough times, let us cheer up.
Let's here opinions,
Jano

[Kryptid]

Kryptid,
the solution does not change the laws of physics.
It strives in them!

So how do you propose to create momentum out of nowhere without violating conservation of momentum?

[Jaaanosik (OP)]

There is and

Kryptid,
the solution does not change the laws of physics.
It strives in them!

So how do you propose to create momentum out of nowhere without violating conservation of momentum?

What do you mean out of nowhere?
I said there would be an energy source and it would do something inside the ship.
No ejection of a mass out is allowed though,
Jano

[Kryptid]

What do you mean out of nowhere?
I said there would be an energy source and it would do something inside the ship.
No ejection of a mass out is allowed though,
Jano

Energy is not momentum.

[Jaaanosik (OP)]

Energy is not momentum.

But it can be used to generate momentum,
Jano

[Kryptid]

But it can be used to generate momentum,
Jano

No, it can't. The net momentum of a system is a conserved quantity.

[syhprum]

The only thing you can create internally to eject is energy use your fusion power plant to drive a laser emitting 0.5 micron  photons and you will get a thrust of 1 Newton for every 300,000 kw if I remember rightly , it will take you a long time to get up much speed

[Janus]

Energy is not momentum.

But it can be used to generate momentum,
Jano

Not net momentum.  Momentum is a vector, it has both magnitude and direction.  You can take a certain store of potential energy and convert it to kinetic energy,    Energy is a scalar, so all you have to worry about is conserving magnitude in terms of conserving energy.   So a compressed spring will have a stored energy of E = 1/2kx^2,  where k is the spring constant and x the amount the spring was compressed.  This can be converted into kinetic energy as mv^2/2. meaning a mass m moving at velocity v.    Energy is conserved.
Momentum also in conserved.  Momentum is mv.   Now in the energy equation, v is squared, thus the direction of  the velocity, which is itself a vector, doesn't matter.  v^2 and (-v)^2 produce the same answer.
However with momentum it isn't,  thus mv is not the same as m(-v), and, in fact, they are opposites.
Like energy, momentum is conserved.  Our mass and compressed spring start with no velocity, so the total momentum is  m(0) = 0.  After the spring has converted its stored energy into kinetic energy of mass m, the total momentum must still be 0.
The only way to do this to divide m in two where m1+m2 = m and then  m1v1 + m2v2 = 0   Since m cannot be negative, either v1 or v2 must be negative,  Meaning m1 and m2 must be sent in opposite directions.  The only way to get m1 moving to the right at v1, is to have m2 moving to the left at v2 such that the sum of the momenta add up to zero.

[A-wal]

I think this can be answered with simple logic.

A propulsion system that's entirely internal can have no external effect but wanting the ship to accelerate is itself an effect that's external to the ship so you're asking if you can exert an external influence without exerting an external influence.

So no, no you can't.

[Jaaanosik (OP)]

Energy is not momentum.

But it can be used to generate momentum,
Jano

Not net momentum.  Momentum is a vector, it has both magnitude and direction.  You can take a certain store of potential energy and convert it to kinetic energy,    Energy is a scalar, so all you have to worry about is conserving magnitude in terms of conserving energy.   So a compressed spring will have a stored energy of E = 1/2kx^2,  where k is the spring constant and x the amount the spring was compressed.  This can be converted into kinetic energy as mv^2/2. meaning a mass m moving at velocity v.    Energy is conserved.
Momentum also in conserved.  Momentum is mv.   Now in the energy equation, v is squared, thus the direction of  the velocity, which is itself a vector, doesn't matter.  v^2 and (-v)^2 produce the same answer.
However with momentum it isn't,  thus mv is not the same as m(-v), and, in fact, they are opposites.
Like energy, momentum is conserved.  Our mass and compressed spring start with no velocity, so the total momentum is  m(0) = 0.  After the spring has converted its stored energy into kinetic energy of mass m, the total momentum must still be 0.
The only way to do this to divide m in two where m1+m2 = m and then  m1v1 + m2v2 = 0   Since m cannot be negative, either v1 or v2 must be negative,  Meaning m1 and m2 must be sent in opposite directions.  The only way to get m1 moving to the right at v1, is to have m2 moving to the left at v2 such that the sum of the momenta add up to zero.

Janus,
agreed, this is all good.
Having said that I am not going to break the physics laws, I am going to bend them, literally.
Before going further a statement/disclaimer:

If this is going to be proven as a viable propulsion system I claim prior art/design and it is my wish this design belongs to public domain/all human kind.

Jano




Let us discuss.
Is this going to work?

[Kryptid]

Shooting the balls from back to front will produce exactly the opposite forward momentum as shooting them front to back. There will be no net movement after one cycle.

It won't work.

[Janus]

Energy is not momentum.

But it can be used to generate momentum,
Jano

Not net momentum.  Momentum is a vector, it has both magnitude and direction.  You can take a certain store of potential energy and convert it to kinetic energy,    Energy is a scalar, so all you have to worry about is conserving magnitude in terms of conserving energy.   So a compressed spring will have a stored energy of E = 1/2kx^2,  where k is the spring constant and x the amount the spring was compressed.  This can be converted into kinetic energy as mv^2/2. meaning a mass m moving at velocity v.    Energy is conserved.
Momentum also in conserved.  Momentum is mv.   Now in the energy equation, v is squared, thus the direction of  the velocity, which is itself a vector, doesn't matter.  v^2 and (-v)^2 produce the same answer.
However with momentum it isn't,  thus mv is not the same as m(-v), and, in fact, they are opposites.
Like energy, momentum is conserved.  Our mass and compressed spring start with no velocity, so the total momentum is  m(0) = 0.  After the spring has converted its stored energy into kinetic energy of mass m, the total momentum must still be 0.
The only way to do this to divide m in two where m1+m2 = m and then  m1v1 + m2v2 = 0   Since m cannot be negative, either v1 or v2 must be negative,  Meaning m1 and m2 must be sent in opposite directions.  The only way to get m1 moving to the right at v1, is to have m2 moving to the left at v2 such that the sum of the momenta add up to zero.

Janus,
agreed, this is all good.
Having said that I am not going to break the physics laws, I am going to bend them, literally.
Before going further a statement/disclaimer:

If this is going to be proven as a viable propulsion system I claim prior art/design and it is my wish this design belongs to public domain/all human kind.

Jano




Let us discuss.
Is this going to work?

All youv'e done here is fail to account for all the momentum transfers between balls and tubes.  You will get no net gain of momentum with this set up. 

I always amazes me that people believe that they are the first person to think up such an idea.  I can't tell you how many times I've seen the same type of idea tossed around.  The reason we don't already have devices that use this type of arrangement is that they just don't work. 

[Petrochemicals]

For a third opinion, see: https://www.thenakedscientists.com/forum/index.php?topic=79146.msg598377#msg598377

Yes,
I've seen that. That's the reason I said no interaction with outside fields.
Just something happening inside the ship itself,
Jano

Is not gravity a worthy outside field ? If you cannot interact with an outside field you cannot go anywhere because nothing exists, there would not be a consept of outside, just like there is not a consept of outside the universe in a massive way as that would be part of the universe, thus inside it.