<p>hi peeps, sorry but i have a silly question but would like to hear your views on it.</p><p> (hopefully i've posted in the right forum) </p><p> my self and a group of collegues were arguing about momentum in space.</p><p> we all know that if you "pushed off" from a dead stationary object you would be propelled in a direction away from the object. if space was a complete vacuum you would keep going and going for eternity (excluding air and food and lifespan etc). </p><p> but my argument is, isn't the space-dust / particles / radiation in space enough to slow you down over 1 year / 1000 years / 1 billion years etc. in other words would you not stop "eventually" as slowed down by the particles in space?</p><p> obviously i'm also excluding blackholes, planets, stars and other gravitational interference as well.</p><p> just a silly question but we're all interested in what would actually happen.</p><p> thanks</p><p> </p><p> kev </p><p> </p>
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</p><p>Its a tricky situation due to the uncertainties in your question. the Short answer is yes the interactions you speak of are likely to slow you down in some respects, or even make you change direction. Given enough interactions and collisions and enough time you may even come to a complete dead stop for a very limited amount of time (though this in my mind is debatable), is anything in the universe ever stationary for any amount of time? What is stop or stationary, is there any such preferential stastic reference frame you could possibly measure this from?</p><p>The sticky bit here is that every atom in the universe exerts a force on every other atom through gravity, so a dead stop ( depending on your reference frame ) is probably not so much of a reality; for as soon as you stop, the forces that stopped you would probably start you in another direction, and the process will continue. </p><p>Another problem is with the current expanding of the universe and how it might interact with the question you laid out, to give you a better answer we might need to nail the specific parameters of your question a little more. Ie are we talking a hypothetical universe or this one. are we factoring the expanding universe and the current standard model of understanding, or just a more light hearted simplified model.</p><p>I hope this helps, though I'm sure someone else can give you a better answer.</p><p> </p><p> </p> <div class="Discussion_UserSignature"> <p align="center"><font color="#808080">-------------- </font></p><p align="center"><font size="1" color="#808080"><em>Let me start out with the standard disclaimer ... I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog. With that out of the way, I have several stupid questions... </em></font></p><p align="center"><font size="1" color="#808080"><em>*** A few months blogging can save a few hours in research ***</em></font></p> </div>
</p><p>Its a tricky situation due to the uncertainties in your question. the Short answer is yes the interactions you speak of are likely to slow you down in some respects, or even make you change direction. Given enough interactions and collisions and enough time you may even come to a complete dead stop for a very limited amount of time (though this in my mind is debatable), is anything in the universe ever stationary for any amount of time? What is stop or stationary, is there any such preferential stastic reference frame you could possibly measure this from?</p><p>The sticky bit here is that every atom in the universe exerts a force on every other atom through gravity, so a dead stop ( depending on your reference frame ) is probably not so much of a reality; for as soon as you stop, the forces that stopped you would probably start you in another direction, and the process will continue. </p><p>Another problem is with the current expanding of the universe and how it might interact with the question you laid out, to give you a better answer we might need to nail the specific parameters of your question a little more. Ie are we talking a hypothetical universe or this one. are we factoring the expanding universe and the current standard model of understanding, or just a more light hearted simplified model.</p><p>I hope this helps, though I'm sure someone else can give you a better answer.</p><p> </p><p> </p> <div class="Discussion_UserSignature"> <p align="center"><font color="#808080">-------------- </font></p><p align="center"><font size="1" color="#808080"><em>Let me start out with the standard disclaimer ... I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog. With that out of the way, I have several stupid questions... </em></font></p><p align="center"><font size="1" color="#808080"><em>*** A few months blogging can save a few hours in research ***</em></font></p> </div><p><span style="border-collapse:collapse;font-size:12px" class="Apple-style-span">"I hope this helps, though I'm sure someone else can give you a better answer."</span></p><p> </p><p>Actually bojangles you were extremely thorough, thanks </p><p> I understand your point about a "dead stop" as it all about referenced distance to something else so you could never be completely motionless (I wonder if you could ever achieve "true motionless", maybe time would stop or the universe would collapse etc lol).</p><p> </p><p> I think the universe in my Q would have to be completely hypothetical, because otherwise we would 'have' to include gravity of stars etc, so the question would then be: how long will i keep going? - answer: until you was pulled into a gravity well etc, which wouldn't be of much help. </p><p>so the question would have to be based on a hypothetical universe, no planets, no stars, no expanding universe. </p><p>lots and lots of space dust and particles. you travelling in a direction from an imaginary reference point.</p><p>the question is then: would your speed decrease, the further you get from the reference? which you've already covered as "yes the interactions are likely to slow you down". </p><p>Thanks again for your reply</p><p>kev </p>
</p><p> I understand your point about a "dead stop" as it all about referenced distance to something else so you could never be completely motionless (I wonder if you could ever achieve "true motionless", maybe time would stop or the universe would collapse etc lol).</p><p> </p><p> I think the universe in my Q would have to be completely hypothetical, because otherwise we would 'have' to include gravity of stars etc, so the question would then be: how long will i keep going? - answer: until you was pulled into a gravity well etc, which wouldn't be of much help. </p><p>so the question would have to be based on a hypothetical universe, no planets, no stars, no expanding universe. </p><p>lots and lots of space dust and particles. you travelling in a direction from an imaginary reference point.</p><p>the question is then: would your speed decrease, the further you get from the reference? which you've already covered as "yes the interactions are likely to slow you down". </p><p>Thanks again for your reply</p><p>kev </p>- Status
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