<p>Can they see the stars? If not then motion is undetectable in a closed environment as it would constitute an inertial frame. But even if they could see the "stars" presumably these would be generated by some form of display technology and behave consistently with the supposed mission profile.</p>

<p>However acceleration is detectable, it would manifest as a gravity like force. The way gravity varies withing the environment could indicate that this was a planetary field rather than an artificial one (depending on how the artificial gravity is supposedly generated). I would expect the payload will have been told some story that would explain this away though.</p>

CC BY-SA 3.0
2015-03-06T06:15:13.950Z
2015-03-06T06:15:13.950Z
Conrad Turner
<p>It is part of General Relativity that if you are in a (small) closed box, you cannot tell the difference between acceleration and a gravitational field.</p>

<p>I suppose you could argue that you would explain Earth's gravity to the occupants of the biosphere as a 1g acceleration away from the Earth for 50 years, a slow swivel of the spacecraft, and then deceleration at 1g for 50 years.</p>

<p>It is hard to say whether such a deception is possible without more details, but in principle it could be done if you have some way of obscuring the initial part of the journey - launch etc, where you would think some non-uniform acceleration would be inevitable.</p>

<p>There is also the question of how far you are going and whether there is a feasible propulsion system. An acceleration of 1g for only a year gets you up to relativistic speeds. You could easily travel to other <em>galaxies</em> in 50 years at this acceleration. So, if the destination was supposed to be a nearby star then the deception fails miserably, unless you try to convince the passengers that you are executing some sort of weird trajectory to get there.</p>

<p>Additionally, how big is the biosphere? What about tides due to the Sun and moon? Any sizeable body of water would show up tides (and indeed possibly the coriolis force due to the Earth's rotation).</p>

CC BY-SA 3.0
2015-03-06T07:28:21.733Z
2015-03-06T08:58:26.660Z
2015-03-06T08:58:26.660Z
ProfRob
<p>In the television show " Ascension " they are supposed to be 50 years into a 100 year journey to another Star System but get this, they never left Earth . They are here on Earth in a huge biosphere . My question is if this is possible that people can be here on Earth and not know that they are not traveling through Space in a Spacecraft ? How could they not have instruments or any other way of not knowing . This plot seems a little far fetched to me, what do the rest of you have to say about it ?</p>

CC BY-SA 3.0
2015-03-06T00:17:28.157Z
My question is a valid and legitimate question and I don't see why it would be down voted with not even a reason given ? The question may belong in a television forum perhaps but it is a Science question so as such it has a reason  to be posted here.
Peter U
<interstellar-travel>
Detecting motion
Peter U
# Detecting motion

(Asked by: username_0 on 2015-03-05)

In the television show " Ascension " they are supposed to be 50 years into a 100 year journey to another Star System but get this, they never left Earth . They are here on Earth in a huge biosphere . My question is if this is possible that people can be here on Earth and not know that they are not traveling through Space in a Spacecraft ? How could they not have instruments or any other way of not knowing . This plot seems a little far fetched to me, what do the rest of you have to say about it ?

**Tags:** interstellar-travel
> **Comments:**
> **username_0**: My question is a valid and legitimate question and I don't see why it would be down voted with not even a reason given ? The question may belong in a television forum perhaps but it is a Science question so as such it has a reason  to be posted here.  

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## 2 answers

### Answer by username_1 on 2015-03-06. Score: 2

Can they see the stars? If not then motion is undetectable in a closed environment as it would constitute an inertial frame. But even if they could see the "stars" presumably these would be generated by some form of display technology and behave consistently with the supposed mission profile.

However acceleration is detectable, it would manifest as a gravity like force. The way gravity varies withing the environment could indicate that this was a planetary field rather than an artificial one (depending on how the artificial gravity is supposedly generated). I would expect the payload will have been told some story that would explain this away though.


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### Answer by username_2 on 2015-03-06. Score: 2

It is part of General Relativity that if you are in a (small) closed box, you cannot tell the difference between acceleration and a gravitational field.

I suppose you could argue that you would explain Earth's gravity to the occupants of the biosphere as a 1g acceleration away from the Earth for 50 years, a slow swivel of the spacecraft, and then deceleration at 1g for 50 years.

It is hard to say whether such a deception is possible without more details, but in principle it could be done if you have some way of obscuring the initial part of the journey - launch etc, where you would think some non-uniform acceleration would be inevitable.

There is also the question of how far you are going and whether there is a feasible propulsion system. An acceleration of 1g for only a year gets you up to relativistic speeds. You could easily travel to other *galaxies* in 50 years at this acceleration. So, if the destination was supposed to be a nearby star then the deception fails miserably, unless you try to convince the passengers that you are executing some sort of weird trajectory to get there.

Additionally, how big is the biosphere? What about tides due to the Sun and moon? Any sizeable body of water would show up tides (and indeed possibly the coriolis force due to the Earth's rotation).


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