[HN Gopher] Very fast rocket
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Very fast rocket
Author : naetius
Score : 146 points
Date : 2021-08-07 20:04 UTC (2 hours ago)
(HTM) web link (makc.github.io)
(TXT) w3m dump (makc.github.io)
| [deleted]
| xwdv wrote:
| Why stop at 0.95c? Why not just let it go even higher so we can
| see what would really happen in FTL travel
| ordu wrote:
| I think, divisions by zero would happen.
| alphabet9000 wrote:
| i cloned the repo earlier to see what would happen. difference
| between .95c and .999c is unremarkable. equal to and above 1
| results in all of the geometry disappearing, just shows black.
| geofft wrote:
| _You find a number of ships fleeing from a small space station.
| You hail them, asking what 's wrong: "Help! We're being overrun
| by some sort of giant alien spiders!"_
| techrat wrote:
| Because FTL travel is not possible, so there's no way to know
| what would 'really happen.'
| _Microft wrote:
| Also check out the game "A Slower Speed of Light" [0] if you are
| interested in visualization of relativistic effects. It includes
| effects like Doppler shifting of colors, perceived warping of
| space and time dilation. Good luck at not getting nauseous.
|
| [0] http://gamelab.mit.edu/games/a-slower-speed-of-light/
| Uehreka wrote:
| Although if you're on macOS Catalina or higher, the game no
| longer runs. And since the team abandoned it without open
| sourcing it[0], it can't be recompiled for 64-bit.
|
| [0] Although they did open source some of their scripts and
| shaders as a Unity plugin called OpenRelativity, which was
| cool.
| jeroenhd wrote:
| Was about to post this. This demonstration helped me understand
| the abstract physics at high speeds better than any book ever
| did.
|
| I didn't suffer any motion sickness, but if there's a game that
| can induce it in you from just a monitor, this is probably that
| game.
| riwsky wrote:
| Yet again, a bunch of web technologies trying to approach the
| speed of c
| eloeffler wrote:
| I c what you did there
| ugjka wrote:
| Don't worry, WebC is coming... sooon
| lmilcin wrote:
| There is a reason the scale stops at 0.95c.
| mattowen_uk wrote:
| OK, so here's a question that I've never been able to find a
| clear answer for (that I understood)...
|
| Say I'm sitting on the bridge of a spaceship travelling N-times
| the speed of light. I'm facing forward. What do I see? Am I
| blinded because photons from far off stars are hitting my eyes at
| an increased rate?
|
| Also, if I look to the left and the right, and behind me? What do
| I see ?
|
| In Star Trek, it's all stripy-stars, and I'm sure that's _not_
| correct.
| kadoban wrote:
| The question likely makes no sense, you can't travel at N-times
| the speed of light for N >= 1. If we're wrong and you can, we
| probably have no idea what it'd look like.
|
| You could kind of guess by trying to extend our models out to
| those speeds, but I think you're going to just find random
| guesses and formulas that no longer make any sense because
| you've exceeded the range of values they're defined over.
| db48x wrote:
| You cannot go faster than the speed of light.
|
| But what you can do is imagine what would happen if you reached
| the speed of light.
|
| Length contraction means that while you and your ship appear to
| be the normal size, the universe around you shrinks along the
| direction of travel. The faster you go, the less distance there
| is in front and behind you. At the speed of light, the entire
| width of the universe shrinks to zero.
|
| Also, you are at the same time experiencing time dilation.
| Although time on board your ship advances at the normal rate,
| time outside the ship appears to slow down. When you reach the
| speed of light, the rate of time passing outside the ship goes
| completely to zero.
|
| Together these mean that the universe outside your ship
| effectively vanishes! It occupies no volume, and has no events
| in it. At the speed of light, your current position and your
| destination are the _same place_, because there is no distance
| and no time separating them.
|
| This is why you cannot go faster than the speed of light. There
| aren't any speeds faster than that.
|
| This video takes a round-about route to get there, but it has a
| nice visualization: https://www.youtube.com/watch?v=HU6t8QvGZmA
| EugeneOZ wrote:
| N>1 - you see the past, N<0 - you'll see the future. It's
| simple.
| contravariant wrote:
| I'm not too sure this question is well-posed, there simply
| isn't an isometry of space that would take a trajectory
| traveling faster than the speed of light and make it inertial.
| As such we have no description of the laws of physics that
| someone would experience on such a trajectory. So how things
| like red/blue-shifting etc. would work out is simply not
| knowable.
|
| Now if you were just wondering what you'd see if you simply
| changed position really quickly then you can just imagine
| putting lots of cameras in a long straight line and triggering
| them in turn to simulate a superluminal speed then you
| basically would just see the stars move more quickly than
| possible. You'd also see time progressing backwards on the
| stars that you are 'moving' away from and more quickly on the
| stars that you are 'approaching'.
|
| So the stripy stars bit is not really that far off.
| superposeur wrote:
| Assuming N<1, you see a scrunched up, blue-shifted version of
| the night sky in the forward direction and very little in the
| aft direction... this is a combination of the fact that the
| stars at the various grid points where the stars are _now_ are
| truly Lorentz-transformed to be more numerous in the forward
| direction + the usual "aberration" effect accounting for the
| fact that you are seeing the stars at the retarded time where
| they _were_ when their light was emitted, not right now. See:
| https://math.ucr.edu/home/baez/physics/Relativity/SR/Spacesh...
| WorkLobster wrote:
| One thing I don't understand about what this page seems to
| suggest: shouldn't there be a bright ring of starlight at
| some non-zero angle away from dead ahead?
|
| Given a finite collection of objects out to a certain radius
| (stars), relativistic length contraction will compress it
| along the direction of travel, so an observer looking out
| from the centre should see the density increase to a maximum
| when perpendicular to the contracted direction (in a way
| that's sort of the opposite of synchrotron radiation ending
| up tightly directed forward and backward). I guess the
| aberration described in your link will bend this fore-wards
| from the perpendicular, but it seems like it should still be
| visible.
| kxrm wrote:
| That's a good question, I am naive to this as well. However my
| guess is that if you looked forward you would see a dilation
| effect. Looking backward, you would see the same, just
| reversed. If you could go faster than light then looking behind
| you would be darkness (since light can't catch you). However
| looking forward, could it be that normal light is dilated to
| such a degree that we change perspective and can see things
| normally not in our visual range (like Infrared)?
| z2210558 wrote:
| IIRC the light coming from in front of you gets blue shifted,
| each photon increasing in energy, and the count increases
| because of the geometric changes you see in the video (the
| angles in front seem to shrink).
|
| Light from the rear red shifts (each photon has less energy),
| and there are fewer as some of the (formerly incident) photons
| "rotated" to the front.
|
| (edit: typo)
|
| (edit: didn't read the question closely, this is about
| approaching c, not exceeding it)
| simonh wrote:
| Since you can't travel faster than light in continuous space
| time there is no way to answer this. At the speed of light
| relativistic distortions lead to a singularity, so bye bye
| spacetime.
|
| The one even faint possibility we know of, the Alcubier effect,
| puts you in a bubble of space time and warps that so it
| propagates at FTL speeds, but within that space time bubble you
| are stationary. You wouldn't see anything outside the bubble
| though as it's beyond an extreme distortion of space time that
| light cannot penetrate.
| Maursault wrote:
| > Since you can't travel faster than light
|
| The Relativity prohibition is that anything with mass can not
| travel _as fast as_ light because approaching c, mass
| increases requiring more and more energy while time slows,
| such traveling at c increases apparent mass to infinity,
| requires infinite energy, and time slows to a stop. The same
| thing could be said for anything moving FTL, as it approaches
| c, mass increases and time slows to zero. Relativity does not
| prohibit FTL travel, only travel at c.
| contravariant wrote:
| The problem is a bit deeper than that, it doesn't just
| require infinite energy there simply is no isometry of
| space that can transform something faster than the speed of
| light into something slower than the speed of light and
| vice-versa. So really there's no way to map the laws of
| physics for something faster than light onto those for
| something moving slower than light. For similar reasons
| there are no known elementary particles that can maintain
| their existence in a superluminal trajectory.
| michaelsbradley wrote:
| Something I found very interesting when I learned about it
| several years ago: it's possible to formulate SR and GR with the
| Euclidean (++++) metric instead of the Minkowski (+---) or (-+++)
| metric. Such a formulation (there is a variety of them) is
| sometimes called Euclidean Relativity (ER).
|
| See: https://www.euclideanrelativity.com/
|
| Some ER research is particularly fascinating to me, e.g.
| Montanus' work on Flat Space Gravitation:
|
| https://link.springer.com/article/10.1007/s10701-005-6482-0
| A new description of gravitational motion will be proposed. It is
| part of the proper time formulation of physics as presented on
| the IARD 2000 conference. According to this formulation the
| proper time of an object is taken as its fourth coordinate. As a
| consequence, one obtains a circular space-time diagram where
| distances are measured with the Euclidean metric. The
| relativistic factor turns out to be of simple goniometric origin.
| It further follows that the Lagrangian for gravitational dynamics
| does not require an interpretation in terms of curvature of
| space-time. The flat space model for gravitational dynamics leads
| to the correct predictions for the bending of light, the
| perihelion shift of Mercury and gravitational red-shift. The new
| theory is free of singularities.
| splittingTimes wrote:
| So that means at 0.95c i would see stuff that is in periphery
| below or beside me, in the frontal of my vision? Is at 0.995c
| then every in front of me?
| dleslie wrote:
| Is there a fragment shader for this?
| throwaway2568 wrote:
| Looks nice, I used a more complicated version during undergrad
| for a physics lab. It was great as you could explore length
| contraction, time dilation etc, and also had toggles for enabling
| some of the really crazy relativistic effects.
| https://people.physics.anu.edu.au/~cms130/RTR/
|
| Turns out it relied on GPU acceleration at the time to work (even
| at low Res). https://arxiv.org/abs/physics/0701200
|
| Might be interesting for someone to port it to a browser version
| anderskaseorg wrote:
| No, the space being shown here remains entirely flat. There is
| length contraction and time dilation at play, but that's a
| uniform effect. The reason the image _appears_ distorted is
| because we have more time to catch up to light rays emitted from
| farther away. This visual phenomenon is called Terrell rotation.
|
| https://en.wikipedia.org/wiki/Terrell_rotation
|
| It's based entirely on special relativity--not to be confused
| with general relativity, which deals with curved spacetime in the
| presence of gravitational fields.
| dang wrote:
| Submitted title was "Website to observe how space is curved the
| closer you get to the speed of light". We got complaints about
| that, so have reverted to the web page's own title.
|
| " _Please use the original title, unless it is misleading or
| linkbait; don 't editorialize._" -
| https://news.ycombinator.com/newsguidelines.html
| esoterae wrote:
| Why does the slider conflate position with velocity? Leave it at
| 0.95c for a minute, put it back to zero, then watch as your
| position is re-set back to 0. Subsequently slide it back to
| 0.95c, your position is magically fast-forwarded to your previous
| position, along with resumption of velocity.
| gpsx wrote:
| Some of the funny effects seen here come not from relativity but
| from the finite time of propogation. In fact, relativity
| _reduces_ the effect of you see from time of propogation. An
| example is that objects seem to be curved, because it takes more
| time for the light from there to get to you, and you move in that
| time. With relativity, this apparent curvature is less.
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