Why Interstellar Travel is Physically Impossible.

[WorldWatcher]

From Google AI...

Yes, inertia creates artificial gravity through acceleration or rotation. By forcing an object to move in a circle (centripetal force), an occupant's inertia causes them to push against the outer wall, creating a "centrifugal force" that simulates the downward pull of gravity.

I don't care what "AI" says.

"Inertia: a property of matter by which it remains at rest or in uniform motion in the same straight line unless acted upon by some external force"

"Inertia" doesn't generate artificial gravity because inertia requires that there is no application of force to accelerate, decelerate, or change direction.

Acceleration is required to achieve artificial gravity for space craft in the context of the discussion.

If an acceleration of 1 G is being generated that cannot happen simply through propulsive interia, there must be propulsive acceleration.

WW

Definition of INERTIA

a property of matter by which it remains at rest or in uniform motion in the same straight line unless acted upon by some external force; an analogous property of other physical quantities (such as electricity); indisposition to motion, exertion, or change : inertness… See the full definition

www.merriam-webster.com

 

[WorldWatcher]

Do you need fuel for all this acceleration-DE acceleration? Or does the planet in question pull you in with its gravity?

Even with nuclear propulsion system (either Nuclear Thermal Propulsion (NTP) or Nuclear Electric Propulsion (NEP)) there must be a fuel.

While both are considered very efficient compared to current chemical rockets, you still need to haul enough fuel to burn for years.

WW

 

[Carl in Michigan]

Do you need fuel for all this acceleration-DE acceleration? Or does the planet in question pull you in with its gravity?

Do you think a planet orbiting Alpha Centauri is going to pull you in?
Yes, if you're accelerating you need fuel
Then you need fuel to "brake"
Yeah it ain't gonna happen. This is just a hypothetical

 

[Carl in Michigan]

I don't care what "AI" says.

"Inertia: a property of matter by which it remains at rest or in uniform motion in the same straight line unless acted upon by some external force"

"Inertia" doesn't generate artificial gravity because inertia requires that there is no application of force to accelerate, decelerate, or change direction.

Acceleration is required to achieve artificial gravity for space craft in the context of the discussion.

If an acceleration of 1 G is being generated that cannot happen simply through propulsive interia, there must be propulsive acceleration.

WW

Definition of INERTIA

a property of matter by which it remains at rest or in uniform motion in the same straight line unless acted upon by some external force; an analogous property of other physical quantities (such as electricity); indisposition to motion, exertion, or change : inertness… See the full definition

www.merriam-webster.com

There is no disagreement. Why do you think there is? Lose the ego

 

[Churchill]

From Google AI...

Yes, inertia creates artificial gravity through acceleration or rotation.

That's a slightly misleading thing to say, AI really shouldn't phrase it that way.

The core axiom of general relativity is the principle of equivalence. It is the basis of the theory, there is no observable difference between inertia in an accelereated reference frame and gravitation in a non-accelerated reference frame.

So that AI answer masks that deep truth, it just hides the profound basis of the theory.

By forcing an object to move in a circle (centripetal force), an occupant's inertia causes them to push against the outer wall, creating a "centrifugal force" that simulates the downward pull of gravity.

OK, I'll let that one stand.

 

[Churchill]

I don't care what "AI" says.

"Inertia: a property of matter by which it remains at rest or in uniform motion in the same straight line unless acted upon by some external force"

"Inertia" doesn't generate artificial gravity because inertia requires that there is no application of force to accelerate, decelerate, or change direction.

Acceleration is required to achieve artificial gravity for space craft in the context of the discussion.

If an acceleration of 1 G is being generated that cannot happen simply through propulsive interia, there must be propulsive acceleration.

WW

Definition of INERTIA

a property of matter by which it remains at rest or in uniform motion in the same straight line unless acted upon by some external force; an analogous property of other physical quantities (such as electricity); indisposition to motion, exertion, or change : inertness… See the full definition

www.merriam-webster.com

Einstein was deeply puzzled by inertia, he couldn't explain it because acceleration has to be relative to something but what?

This is captured in an idea named Mach's Principle:

https://www.americanscientist.org/article/the-forgotten-mystery-of-inertia

 

[ShahdagMountains]

Do you think a planet orbiting Alpha Centauri is going to pull you in?
Yes, if you're accelerating you need fuel
Then you need fuel to "brake"
Yeah it ain't gonna happen. This is just a hypothetical

I’m not thinking anything. Just asking questions.

You don’t need to be so condescending.

 

[Churchill]

This is a thought experiment from Einstein's The Meaning of Relativity.

Imagine two identical fluid spheres isolated in otherwise empty space, separated so widely that they exert no meaningful gravitational influence on one another. One sphere rotates about the line connecting them, while the other remains at rest. The rotating sphere takes on an oblate shape, while the non‑rotating one stays perfectly spherical. But if there is no absolute space to define rotation, what singles out the rotating sphere? What physical mechanism produces its deformation? The explanation cannot lie in motion relative to empty space, or the motion of one sphere relative to the other, but must instead involve the relation of each sphere to the mass distribution of the universe as a whole.

A person standing on each sphere (on the pole, where the imaginary line between them passes) looking up will see the other sphere rotating (the rotation is relative) but only one of the spheres is deformed, why...

 

[Carl in Michigan]

I’m not thinking anything. Just asking questions.

You don’t need to be so condescending.

Thats what I'm seeing in everyone in this discussion.
What I posted is talking about TIME to reach the nearest star, not fuel
You CANNOT go from zero to light speed instantly. You have to accelerate. If you're spending YEARS in space you need gravity. You'll get "gravity" by accelerating At 1 g.

It takes 1 year to accelerate to light speed at 1g. But halfway into the he trip you have to turn the ship around and "brake." So you're not going at the speed of light for the 4 years it takes light to travel that distance.

"Warp drive" is NOT possible.

Instant acceleration would cause your spaceship to explode with the force of a thermonuclear bomb.

For that matter, if your ship hit ANYTHING at light speed, it's over

 

[Kruska]

Load of rubbish - something that was to be expected to be posted by ShahdagMountains

 

[ShahdagMountains]

Load of rubbish - something that was to be expected to be posted by ShahdagMountains

So you’re upset. I must have got to you. Iol.

 

[Admiral Rockwell Tory]

Interia doesn't generate artificial gravity. There are only two methods, currently which simulate artificial gravity:

Interia is the tendency of a body to continue in it's current state (at rest or movement) unless the state is changed by some force. Current rocket systems generate inertia - which allows the rocket to travel in space - but using high thrust short duration acceleration. Once the acceleration stops, there are no longer "G" forces.

First, acceleration. For acceleration to provide constant gravity for a trip through space, the acceleration profile would have to change from "high thrust/costing" to constant acceleration under power for the duration of the trip. As a side note a constant acceleration equal to 1 "G" would reduce the travel time from Earth to Mars from 6-9 months to less than 2 days. The down side is the ship would be traveling at over 1,000,000 kilometers/second and wouldn't be able to stop. Even with a mid-courese "flip" and decelerating (which would again produced 1 "G" for the occupants, the travel time would be less than a week.

Second, is generation of "rotational gravity" through centrifugal force. The problem is the diameter of the rotating "circle" has to be large enough to minimize coriolis effects and the mechanical systems invovled have to be EXTREAMLY mechanically sound to (a) rotate properly, (b) withstand the stress of acceleration and deceleration. Current rocket technology does not allow for the lifting of such a ship to space. It would have to be constructed in orbit, then set into it's rotation. Such a ship would be massive and would not reduce travel time when compared to the constant acceleration model.

WW

Inertia. Two wrong. One right.

 

[Godboy]

I don't care what "AI" says.

"Inertia: a property of matter by which it remains at rest or in uniform motion in the same straight line unless acted upon by some external force"

"Inertia" doesn't generate artificial gravity because inertia requires that there is no application of force to accelerate, decelerate, or change direction.

Acceleration is required to achieve artificial gravity for space craft in the context of the discussion.

If an acceleration of 1 G is being generated that cannot happen simply through propulsive interia, there must be propulsive acceleration.

WW

Definition of INERTIA

a property of matter by which it remains at rest or in uniform motion in the same straight line unless acted upon by some external force; an analogous property of other physical quantities (such as electricity); indisposition to motion, exertion, or change : inertness… See the full definition

www.merriam-webster.com

No, i was right and Google confirmed it. I dont care what YOU say. I know that i am right and you are wrong.

 

[WorldWatcher]

No, i was right and Google confirmed it. I dont care what YOU say. I know that i am right and you are wrong.

No you not.

Astronauts in the ISS have inertia do you their acceleration to B orbital velocity.

However, watch them in video. The float and are not under 1G

Don’t let AI do your thinking, think for yourself.

WW

 

[Godboy]

No you not.

Astronauts in the ISS have inertia do you their acceleration to B orbital velocity.

However, watch them in video. The float and are not under 1G

Don’t let AI do your thinking, think for yourself.

WW

The only physically possible way to create a force as strong as earth's gravity that acts on all objects in a ship is through acceleration. Acceleration always creates inertial forces. Inertial forces such as the centrifugal force or Coriolis force are very real in the accelerating reference frame. They are not imaginary or fictional, but are simply non-fundamental in that they arise from the movement of the frame itself. If the acceleration is held constant and at the right value, the inertial force will behave identically to earth's gravity and will, in fact, be equivalent to earth's gravity. This fact is actually a basic tenet of General Relativity. There are two kinds of accelerations, rotational and linear. A ship could achieve artificial gravity by rotating about its axis. To be practical, the radius of rotation would have to be quite large. Additionally, a ship could create artificial gravity by constantly accelerating forwards. Shows that portray artificial gravity without rotation or constant forward acceleration are simply non-physical. Incorrect artificial gravity is often used in movies because of budgeting concerns. It is very expensive to make actors sitting on earth look like space voyagers floating in a space ship, or alternatively, to construct a space ship set that is constantly rotating.

How do space ships make artificial gravity?

Despite the fact that outer space is brimming with gravity, the lack of solid ground in space means that objects without thrust are in a continual ...

www.wtamu.edu

 

[WorldWatcher]

The only physically possible way to create a force as strong as earth's gravity that acts on all objects in a ship is through acceleration. Acceleration always creates inertial forces. Inertial forces such as the centrifugal force or Coriolis force are very real in the accelerating reference frame. They are not imaginary or fictional, but are simply non-fundamental in that they arise from the movement of the frame itself. If the acceleration is held constant and at the right value, the inertial force will behave identically to earth's gravity and will, in fact, be equivalent to earth's gravity. This fact is actually a basic tenet of General Relativity. There are two kinds of accelerations, rotational and linear. A ship could achieve artificial gravity by rotating about its axis. To be practical, the radius of rotation would have to be quite large. Additionally, a ship could create artificial gravity by constantly accelerating forwards. Shows that portray artificial gravity without rotation or constant forward acceleration are simply non-physical. Incorrect artificial gravity is often used in movies because of budgeting concerns. It is very expensive to make actors sitting on earth look like space voyagers floating in a space ship, or alternatively, to construct a space ship set that is constantly rotating.

How do space ships make artificial gravity?

Despite the fact that outer space is brimming with gravity, the lack of solid ground in space means that objects without thrust are in a continual ...

www.wtamu.edu

“ The only physically possible way to create a force as strong as earth's gravity that acts on all objects in a ship is through acceleration.”

Go back and v look.

Thank you. That’s what I said. The force is coming from acceleration in terms of the propulsion system generating artificial gravity.

Glad we agree.

WW

 

[Godboy]

“ The only physically possible way to create a force as strong as earth's gravity that acts on all objects in a ship is through acceleration.”

Go back and v look.

Thank you. That’s what I said. The force is coming from acceleration in terms of the propulsion system generating artificial gravity.

Glad we agree.

WW

You agree with me NOW. You didnt earlier and you were super smug about it.

 

[WorldWatcher]

You agree with me NOW. You didnt earlier and you were super smug about it.

Earlier you said inertia provides artificial gravity, you were wrong and I corrected you. Acceleration curates artificial gravity as part of propulsion.

Take the acceleration due to propulsion away and the “artificial gravity” goes away.

Later you attempted to inject acceleration, which is what I said from the beginning.

Go back and read the posts again.

BTW - are astronauts in the ISS floating or under 1 G?

WW

 

[Fort Fun Indiana]

No, i was right and Google confirmed it. I dont care what YOU say. I know that i am right and you are wrong.

Inertia has nothing nothing to do with acceleration or gravity, strictly. Inertia is just velocity*mass, relative to an arbitrary rest frame.

 

[Carl in Michigan]

Another thing to mess up your trip to the nearest star;
Interstellar space isn't empty. There is dust and even atoms out there -- 1 per cubic centimeter.

Now if you're moving at light speed, and you hit DUST, you're dead.

If an ATOM hits the hull of your space ship at the speed of light, it will erode the hull before you ever reach to ur destination.

At that speed it will actually feel like a wind that will eventually destroy your ship and you

Short answer: it would be catastrophic—those sparse atoms turn into a deadly, high-energy radiation beam when you’re moving near light speed.

Why something so “empty” becomes dangerous

Interstellar space is extremely thin (about ~1 atom/cm³), but at speeds close to the speed of light, each atom you hit carries enormous kinetic energy due to relativistic energy.

Instead of gently bumping into your ship, those atoms behave more like subatomic bullets.

What actually happens on impact

1. Extreme radiation bombardment

Hydrogen atoms slam into the front of your ship at near-light speed.
Their energy is so high they behave like cosmic rays, producing:
Gamma rays
Particle showers (like a mini particle accelerator hitting your hull)

2. Surface erosion and heating

Each impact blasts atoms off your ship’s surface.
Over time, this acts like intense sandblasting—but at relativistic energies.
The front of the ship would heat to extreme temperatures and likely vaporize without protection.

3. Secondary particle cascades

Impacts create showers of high-energy particles that penetrate deeper into the ship.
This would fry electronics and be lethal to humans without heavy shielding.

4. Drag and energy loss

You’d constantly lose energy plowing through these particles.
At true light speed (which isn’t possible for objects with mass), the energy required would be infinite anyway.
A useful way to picture it

At normal speeds:

Space = almost empty

At near light speed:

Space = a continuous beam of radiation hitting your ship head-on