Relativistic Spaceship

https://dmytry.github.io/space/

by thunderbong • 2 years ago

1085 485 2 years ago

dmytry.github.io

cmrx64• 2 years ago

very nice demo.

bl0rg• 2 years ago

cool!

JPLeRouzic• 2 years ago

Thanks for the demo!

sgt3• 2 years ago

Can't get it to slow down to a standstill. Is that a bug?

ortusdux• 2 years ago

Acceleration vs speed. Adjust the acceleration until the "The ship is flying at X% the speed of light" is almost zero.

sgt3• 2 years ago

I did... after approaching near 100% speed of light, I decelerated, but it refuses to budge below around 45%. I accelerated both axes.

sciolizer• 2 years ago

Do you decelerate in both axes?

RajT88• 2 years ago

Sent this to a stoner friend of mine.

throwup238• 2 years ago

It's no accident that the user who submitted this is named "thunderbong"

AnimalMuppet2• 2 years ago

I mean, we are talking about a trip...

layer86• 2 years ago

Now you are staring into the big bang in all its glory

Don’t they mean the CMB?

Retric3• 2 years ago

Blue shift, it’s no longer radio waves if you’re traveling fast enough.

layer86• 2 years ago

Of course it’s not microwaves anymore, but it’s still the CMB, that is, decoupling/recombination, not the big bang. Unless you count the CMB as the big bang.

andsmedeiros• 2 years ago

Sweet

ryandrake6• 2 years ago

Great visualization of the unintuitive nature of special relativity. It's kind of mind blowing to realize that if we could accelerate our spaceship at a mere 1G continuously, we could visit the center of the Milky Way in under 20 years (spaceship time), totally do-able in a human lifespan. Of course 27900 years would have passed on Earth, so you wouldn't be able to tell anyone about your vacation.

m3kw9• 2 years ago

I wonder what is a safe acceleration to get to light speed for long periods without hurtin too much

jtriangle2• 2 years ago

~9.8 m/s sounds pretty comfortable.

bee_rider2• 2 years ago

You can’t “get to” light speed, that’s one of the big punchlines in relativity.

If you pick an acceleration equal to the acceleration we experience on Earth (aka 1g, aka ~9.8m/s^2), you hit relativistic speeds (speeds at which you need to take into account the effects of relativity to do anything) surprisingly fast. On the order of hundreds of days. So, it is not really a matter of safe acceleration on a long space trip. Instead you have to worry about the actual speed you are traveling at—even though space is very empty, there are still atoms floating around out there, and you’ll be moving at very high speeds relative to them, leading to interesting collisions.

AlexAndScripts3• 2 years ago

I suppose you would also have to worry about surviving the trip - every atom in the interstellar medium would damage your ship, likely penetrating the entire way through, and electromagnetic repulsion would only work with charged particles.

MilStdJunkie11• 2 years ago

Every proton would have the energy of a baseball. It's bananas. Granted, space is really empty, but it's not that empty, somewhere around a hundred atoms per cubic meter. Your ship might look like a very, very long shooting star. Probably dialing the speed down a touch would be worth it for whatever your shielding material is, but who knows? We're talking miracle engines here. I think in the "Valkyrie" ship-on-a-string concept, they had some sort of magnetic thingummy that generated more power as more stuff smacked into it, then as they decelerated they let out this sort of gas mist to go ahead of the ship and smack into things.

ryandrake6• 2 years ago

Sure, there are plenty of practical problems that would make the trip impossible. The fuel mass alone that would have to be shot out the back to make that trip would be something on the order of 800 million times the mass of the payload (you). So a 100kg person sitting in a 100kg spaceship would require something like 160 billion kg of fuel, assuming zero energy loss in burning the fuel. Relativistic rocket calculators are fun!

perardi3• 2 years ago

Unless you could somehow make an Alcubierre warp drive.

Of course…even if that was possible, it’s conjectured that the colonists already at your destination won’t appreciate you boiling the atmosphere when you hit them with blue shifted radiation.

https://www.universetoday.com/93882/warp-drives-may-come-wit...

otikik• 2 years ago

My ship exterior hull is made of quadratic jergotrons, precisely to avoid that issue.

caturopath• 2 years ago

Why not just increase power to the main deflector?

dylan6043• 2 years ago

Or stopping. It takes the same amount of time to slow down as it did to speed up. Presumably, you'd have to rotate 180° so you are now thrusting in the opposite direction. So at the speeds you've reached to get there in 20 years (ship time), you'd just race on by.

steffenfrost• 2 years ago

Couldn't you shoot an electron bream ahead of the ship to ionize the atoms and the deflect them with a magnetic field?

Terr_• 2 years ago

I wonder how fast the interstellar medium of gas etc. drifts and flows... could sacrificial sweeper-ships drill out a less-dense-holes for other traffic on a reasonable timescale?

csomar• 2 years ago

My ship has a quantum shield that changes the location of incoming atoms; putting them just a bit to the safe side of the ship. Doesn't work with molecules though but that's coming up on v2.

LorenPechtel7• 2 years ago

I remember a StackOverflow question about a one-ton tungsten(?) ball heading towards Earth from the edge of the solar system, I forget how many nines after the decimal point in it's velocity. The question was what what would happen to Earth--and the very surprising answer was basically nothing. The ball would be vaporized very quickly by the interplanetary medium and disperse long before reaching Earth. Some of the energy would hit but it wouldn't be enough to notice.

thatwasunusual2• 2 years ago

We would also need to find a way to slow down.

MagicMoonlight• 2 years ago

You just turn around at the half way point

EA-31676• 2 years ago

It's worth saying that 1G is heavy acceleration to maintain, nothing "mere" about it. When you run the numbers the amount of energy involved basically adds up to needing a rocket made entirely of antimatter, and a similar mass of 'normal' matter to react with.

Keep in mind that when talking about long-distance journeys in space under any sort of constant acceleration, the numbers are generally in thousandths of 1G.

slow_typist3• 2 years ago

But accelerating by 1 g is very convenient for the crew. No muscle and bone degeneration, no space sickness, etc.

jcadam• 2 years ago

Could use such a ship as a time machine (well, that only goes one way).

tshaddox2• 2 years ago

Do you mean that someone in the space ship could, without extending their own lifespan beyond what is already expected, use the space ship to "travel" to Earth's distant future?

daedalus_j• 2 years ago

The Forever War novels have this as a key plot point, if you're interested in that sort of thing.

dtgriscom• 2 years ago

My comfy chair is a one-way time machine.

agos• 2 years ago

obligatory XKCD: https://xkcd.com/209/

lostmsu• 2 years ago

It does not take much more years to the edge of the visible universe.

EA-31676• 2 years ago

Iirc to get to Proxima Centauri at a constant 1g would require a fairly impressive mass of antimatter, to continue to the edge of the observable universe would be so many more orders of magnitude more energy than that it's barely worth discussing. Even though we can't reach c, as we start to approach it the energy requirements rise catastrophically, along with the risk of colliding with some random mote of Hydrogen and remembering that your relative velocity is .99999c, in the moment before you and your ship are atomized.

robofanatic• 2 years ago

How many years will it take to accelerate from normal speed to that speed and decelerate back?

multiplegeorges• 2 years ago

10.

Assuming a straight line and assuming 1G is your max acceleration: you accelerate for 10 years, reach your maximum velocity then flip and do the same thing in the other direction. You'll reach your destination with 0 velocity.

huytersd2• 2 years ago

Time travel seems so easy and we could do it with the tools we have now for the most part. Maybe we’ll never go into the past but relatively contemporary humans are going to be all over the future in all kinds of places.

After the first time it happens people in the future can start to expect a human from the past to keep visiting every so often.

tempestn3• 2 years ago

If that did start happening, it's not like the people from the past would just pop up suddenly. We would be aware of their journey. It's not like a time machine where someone just disappears from the past and appears in the future.

alberth• 2 years ago

accelerate our spaceship at a mere 1G continuously

Do you mean accelerate at 9.8 m/s^2 ?

mcswell2• 2 years ago

But think of all the leave time I'd accumulate!

onetimeuse92304• 2 years ago

Not doable.

There exists nothing, even theoretically that you can put on the spaceship to get you that 1G continuous acceleration.

I don't remember exactly what is the maximum achievable delta V but if I remember well it is not a high portion of the speed of light, more like 60% of speed of light. And that assuming you have crazy things like carry a small black hole with you and use it to convert mass into energy at 40% efficiency.

867-5309• 2 years ago

27900 years would have passed on Earth, so you wouldn't be able to tell anyone about your vacation

you could tell them when they overtake you due to incessant obsolescence

monkeydust• 2 years ago

Its a true mind f*. A round trip would take the best part out of a normal human lifetime but it would appear that you have travelled over 55 thousand years into the future when you return the earth...assuming it's still there.

AlexAndScripts3• 2 years ago

I had no idea you could achieve relevant amounts of time dilation so "easily" with relatively small (1m/s) of constant thrust - such that interstellar travel becomes somewhat viable provided you can continuously accelerate for the entire trip. Googling it, it would take approximately three years of observed time for a traveller to get to alpha centauri at 1g.

Could any somewhat-plausible technologies (fusion etc) get us to that point? I don't know how to do relatavistic maths, but it seems that directly converting mass to energy and ignoring relatavistic effects requires 50 000kg to accelerate 100 000 kg (with a constant relationship, as the C^2 cancels out) to the speed of light.

JumpCrisscross9• 2 years ago

Could any somewhat-plausible technologies (fusion etc) get us to that point?

Nuclear thermal or nuclear pulse propulsion. No fusion needed.

ianburrell2• 2 years ago

Nuclear thermal or pulse, fission or fusion, aren't enough for interstellar relativistic speeds. They have way too low specific impulse. They don't even have enough for constant acceleration inside the solar system unless the acceleration is really low or the fuel ratio is huge.

ben_w9• 2 years ago

For practical values, nuclear pulse propulsion would only get you up to a few percent of the speed of light.

The best nuclear thermal, gas core, would give you 7000 seconds[0]. A "dusty plasma" rocket (suspend the nuclear fuel in dust form in a magnetic field) might get 100,000 seconds, or just over a day of accelerating at 1g.

[0] for the benefit of non-space nerds: the unit of measure is "lb-force seconds per lb-mass of fuel", which is kinda like "seconds at 1g" if the fuel is a very small fraction of the total mass, which it really won't be in a practical rocket.

ianburrell2• 2 years ago

It isn't possible without a magic reactionless drive; it might even require a zero-energy drive since the kinetic energy is huge and needs to come from somewhere.

The rocket equation kills you. A reasonable fusion rocket would require an enormous (like an entire planet worth) to continuously accelerate to relativistic speeds. Antimatter drives are the only option and still require large amounts of reaction mass since have to absorb the energy to throw it out the back, or use a laser.

eek2121• 2 years ago

Well the obvious solution would be to figure out a mechanism to capture the particles that bombard your ship and figure out a way to turn those particles into thrust so you don’t need to take a bunch of fuel with you, which I get it, is another hard problem to solve, but maybe not impossible. We have done some incredible things before.

nabla9• 2 years ago

You need to get around the rocket equation.

we estimate the neutral hydrogen density in the unperturbed local interstellar medium of 0.195 ± 0.033 cm−3 https://iopscience.iop.org/article/10.3847/1538-4357/abb80a

You need a hydrogen 'scoop' and fusion. If you can accelerate to 0.01c, you can collect enough hydrogen for 1000 MW fusion power from 32 km2 (6 km diameter) scoop area. Faster you fly, more you get. You can accelerate until interstellar particles start to do real damage.

MilStdJunkie11• 2 years ago

One gee over the course of months is insane. Even if you converted the entire "fuel" reaction mass directly into momentum, you're still carrying tens or hundreds of thousands of tons of fuel for any remotely habitable spacecraft. And no engine has perfect mass conversion. Matter-Antimatter has been simulated to be maybe sixty percent efficient, fusion is around 17%, nuclear pulse propulsion a surprising 7%, fission nuclear gas rockets might max out at 12% but those numbers are dodgy as we don't have sharp numbers on gas core reactors.

As an SF writer, it's pretty interesting, though, to think of the weird shapes a society would take when your astronauts are outliving entire civilizations. I imagine a sort of neo-Polynesian culture, with travellers never quite knowing how the place will look if they ever come back that way.

Teever2• 2 years ago

What if you didn't carry the fuel? Use stationary lasers from your starting point to power your journey half way until you lasers from your destination to slow your craft down.

ryandrake6• 2 years ago

As an SF writer, it's pretty interesting, though, to think of the weird shapes a society would take when your astronauts are outliving entire civilizations.

I guess this all depends on how you define simultaneity. Say I got on a relativistic rocket traveling near c and colonized Planet X in 10 years ship time and say 20,000 years Earth time. I put up my TV antenna as soon as I land, and I'd still be receiving Earth transmissions from approximately 10 years after I left, no? So even though civilization is long gone from Earth's point of view, from my point of view, I can keep up with the latest news as if I were still living there. So from my point of view I did not outlive anything.

If I were to go back, yes, everything would be gone.

AnimalMuppet2• 2 years ago

Can you explain why matter-antimatter only has 60% efficiency?

knodi1233• 2 years ago

In the book series The Expanse, that was pretty much the only unrealistic technology that the humans had, which allowed them to colonize the solar system. Sure, there was some might-as-well-be-magic alien stuff later in the book, but by page 1, humans have colonized the solar system, purely with a hand-wavy engine that can generate sustained thrust without needing tons of reaction mass and without turning your exhaust port into an unimaginable hell cannon.

EvanAnderson• 2 years ago

I imagine a sort of neo-Polynesian culture

This makes me think of the Quen Ho in Vernoe Vinge's "Zones of Thought" universe.

perardi3• 2 years ago

Have you read Tao Zero?

https://en.wikipedia.org/wiki/Tau_Zero

Classic hard sci-fi. A colony ship’s Bussard ramjet has a glitch, and it cannot stop accelerating—and basically forever, given time dilation.

agent281• 2 years ago

That's basically the plot of the Forever War. When you drop out of hyper drive (or whatever they called it) you never know if you are going to be battling a ship from your future or your past. The very society that you fight for is completely alien. It's incredibly alienating.

marmaduke• 2 years ago

What do you think about the gravity well "drive" in three body problem trilogy? I thought it was fairly clever, especially given the stories describing it beforehand (maelstrom iirc?)

ausp• 2 years ago

As an SF writer, it's pretty interesting, though, to think of the weird shapes a society would take when your astronauts are outliving entire civilizations.

Spin, a novel by Robert Charles Wilson, touches on this from a planetary perspective. Quite the interesting read, though I won't say more here for fear of spoilers.

Keyframe• 2 years ago

as far as we understand, you have to eject mass in order to move there. pick your choice in that regard.

floxy• 2 years ago

"Roundtrip Interstellar Travel Using Laser Pushed Lightsails"

https://ia600704.us.archive.org/view_archive.php?archive=/24...

"A one-way interstellar flyby probe mission uses a 1000 kg (1-metric-ton), 3.6-km-diam. lightsail accelerated at 0.36 m/s2 by a 65-GW laser system to 11% of the speed of light (0.11 c), flying by a Centauri after 40 years of travel. "

"...The third mission uses a three-stage sail for a roundtrip manned exploration of e Eridani at 10.8 light years distance."

qayxc6• 2 years ago

Holy cow! I just read the energy requirements of that third mission. Total electricity generation capacity of the entire world is about 12TW today [1], whereas that 3rd mission would require a "formidable" - as the author admits - 45,000TW at least. A mere three orders of magnitude more :)

[1] https://www.statista.com/statistics/267358/world-installed-p...

Workaccount2• 2 years ago

Even if you can figure out the problem of thrust, you still have to deal with particles slowly swiss-cheesing your ship.

And even beyond that, you either witness the ships leaving and never hear back or you embark on one and comeback to whatever Earth is in thousands of years from now.

darreninthenet• 2 years ago

Even the GPS satellites have to take into special relativity - they have to correct for a tiny amount of time per day due to time dilation causing the moving clocks on the satellites to tick slightly slower than the stationary ones on Earth.

Koshkin3• 2 years ago

Curiously, general-relativistic effects needed to be accounted for as well.

Quoting Wikipedia, GPS “must account for the gravitational redshift in its timing system, and physicists have analyzed timing data from the GPS to confirm other tests. When the first satellite was launched, some engineers resisted the prediction that a noticeable gravitational time dilation would occur, so the first satellite was launched without the clock adjustment that was later built into subsequent satellites. It showed the predicted shift of 38 microseconds per day. This rate of discrepancy is sufficient to substantially impair function of GPS within hours if not accounted for.”

phire2• 2 years ago

Things get more insane the further you go.

After an observed 12 years of constant 1g acceleration, you will be 113,000 lightyears from your point of departure, which is enough distance to cross from earth to the opposite side of our galaxy.

Of course, you are now traveling at 99.999999996% of the speed of light. If you actually wanted to stop at the other side of the galaxy to take a look around, you would need to turn around at the halfway point to decelerate, which roughly doubles the travel time.

galangalalgol• 2 years ago

Is there any relativistic bonus that makes deceleration easier? Does it take less energy to go from 0.999C to 0.99C than to go from 0.009C to 0C?

dgrin91• 2 years ago

Very fun.

What does y represent?

gs17• 2 years ago

It should be the Lorentz factor: https://en.wikipedia.org/wiki/Lorentz_factor

layer86• 2 years ago

Lorentz factor, and it’s a gamma.

klyrs• 2 years ago

Yikes. At around 90%c, it's starting to look like a sunny day. Any physicists care to weigh in on the accuracy of this? I can search for the energy density of starlight in interstellar space... but how fast does one need to go to hit that "sunny day" point?

pixl97• 2 years ago

I'd think the small amount of atoms per cubic meter in interstellar space would make your day very sunny long before you got up to 90%C and the photons out there started to matter.

Koshkin3• 2 years ago

Also, since the whole universe appears to shrink into a thin line, am I in fact moving now in all directions at once?

zamadatix4• 2 years ago

The effect is in the way you see light rays appear to arrive because of your motion. It doesn't really change that those things are really an absolute direction or that you're going in one direction.

BoiledCabbage2• 2 years ago

According to the simulation moving relativistically in addition to shifting the frequency also increases the intensity significantly. Something I had never heard about until now.

I'd love to find a reference for it as I found that surprising too.

zamadatix4• 2 years ago

The more common name to read about it by is "Relativistic Beaming".

mihaaly3• 2 years ago

I wonder how long one would enjoy the view of that sunny day when all the visible light, infrared and high radio frequencies coming our way are turned into high energy x-ray and gamma frequencies due to the doppler effect.

robbomacrae3• 2 years ago

This is something I've wanted to try in VR one day. Does anyone know if there is an app/game available for one of the popular headsets? Is there a technical limit to how realistic the effect could be?

layer86• 2 years ago

Is there a technical limit to how realistic the effect could be?

You won’t feel the acceleration ;) nor the light intensity of the higher velocities (luckily).

its_ethan• 2 years ago

The rate that time is progressing is also going to change this effect a LOT.

Years are passing in seconds in this websites simulation, if you were experiencing it all in "real time" everything would appear pretty much stationary for quite a while.

Even at like 95% the speed of light, you're talking about years of time required to move between stars - nothing will appear to change much day to day until you actually get close to one of them.

zonkerdonker• 2 years ago

Not exactly what youre looking for, but this type of game (using relavistic physics) has been attempted. Heres one built in unity that could be easily ported to a Quest line device.

https://en.m.wikipedia.org/wiki/A_Slower_Speed_of_Light

I also found this render (and game!) that show off some aspects of relativistic spaceflight. https://youtu.be/Ix1XlxF66Zk?si=8HzDH3U-CRM-erRB

I think the technical limit might be moot, better question might be how strong of a stomach you have, geometry gets pretty wacky near c

robbomacrae3• 2 years ago

Thats great! I wonder if the stomach issues would be eased if you were sat in a chair like captain kirk looking through a big panoramic window.

crazygringo• 2 years ago

You won't be able to perceive anything "3D" if you're aiming for accuracy.

Even though we can perceive the "depth" of the stars through motion in this simulation, every star is still going to look equally far away, because their positions won't change between the left and right eyes. The same way we can't perceive the sun as further away than the moon -- depth perception merely tells us they're both "max far away".

You could always introduce depth perception by faking your eyes to be light-years apart, but of course that's not how it would really be in the spaceship...

robbomacrae3• 2 years ago

Yeah I figured that would be the case. I still think it would be really cool effect to see anyway if you could go fast enough and experience the motion parallax of the stars. No offense to this project as it's really impressive.

ok_dad• 2 years ago

Don't forget to accelerate in the opposite direction (move it down) once to see the starlight shift out of visual range! It's fun until about 95% of c then there is just blackness.

pcardoso• 2 years ago

Yeap, and then turn around and see the lights behind you.

MayeulC• 2 years ago

You can also pan the camera around, and even follow stars as they pass by, if you are quick enough with your mouse (or if you don't fly too fast).

A_D_E_P_T• 2 years ago

~850 years of ship time at max acceleration and the universe is 10^30 years old.

At this point, only white dwarfs, neutron stars, and various stellar remnants remain. Galaxies have dissipated, and stars like our Sun are a distant memory. (If any still exist to remember them. Which is, I'll add, not out of the question. Life can cling to structures built around black holes, white dwarfs, etc., and extract energy from those bodies for a very long time.) We're a long, long way from "heat death" -- from the Universe becoming an undifferentiated entropic sea of particles -- but it is already a very different place.

Puts things in perspective.

CobrastanJorji• 2 years ago

You could imagine a technically advanced society using it as a sort of penal death sentence. "You were not safe around our people, so we are sending you to the end of time."

goblinux• 2 years ago

Isn’t that the plot of Skyrim?

trenchgun• 2 years ago

Vernor Vinge, Across the Realtime trilogy

tEMporality7• 2 years ago

The Master did that in Doctor Who

selfawareMammal• 2 years ago

Lots of intelligent comments and I'm just here finding it scary.

amalive2• 2 years ago

Oh god. I thought it was just me.

jschrf• 2 years ago

We live in a really, really big explosion.

ChrisArchitect• 2 years ago

(2020)

This is a relativistic spaceflight simulator which shows what it would look like if you were on a spaceship traveling close to the speed of light. It is loosely based on my original code from 2012 implementing relativistic effects in my game The Polynomial.

https://dmytry.com/games/index.html

Dig1t• 2 years ago

This is downright beautiful.

It's fun to think that this is the closest we could ever come to time travel. I hope someday somebody actually gets to experience this.

mooneater• 2 years ago

If you fly backwards, its just all black

breckenedge• 2 years ago

Redshifted below perception, like the glow from the Big Bang.

amalive2• 2 years ago

Why is this scary ?

PaulHoule• 2 years ago

I re-read this book recently

https://en.wikipedia.org/wiki/Tau_Zero

which has to be one of the most epic sci-fi novels ever since it is about a starship that gets its brakes damaged in a crash so their answer to every problem they face is to go faster!

__MatrixMan__• 2 years ago

I liked that one.

At many points it reminded me of The Freeze Frame Revolution, by Peter Watts (https://tachyonpublications.com/product/freeze-frame-revolut...), which was also quite good in a similar way, if perhaps a bit darker.

0x38B• 2 years ago

I just finished reading Tau Zero after hearing about it here and also recommend it!

I expected relativity to play a role, but the time dilation the crew experienced was on a _far_ grander scale than I imagined. The book also left me thinking of favorite time travel/relativity classics like Interstellar and, going back, Star Trek IV: The Voyage Home (my favorite Star Trek movie).

eh_why_not2• 2 years ago

Beautiful!

For the comments saying we "just" need to maintain a 1G acceleration, should point out that as the ship approaches the speed of light, its mass increases [0].

And as the mass increases, so does the thrust required to maintain that acceleration. So that engine better be able to tap into some magical energy source, otherwise it can't maintain the acceleration at the higher speeds. :)

[0] https://en.wikipedia.org/wiki/Mass_in_special_relativity#Rel...

Edit: this interpretation may not be entirely accurate (comments below).

randallsquared2• 2 years ago

Is the ship gaining mass (and shortening, and having its time slowed) in its own frame of reference? No, right? So wouldn't it be that the 1G acceleration from the viewpoint of the ship remains from the internal perspective, even though near the speed of light, more and more of that energy goes into higher mass and slower time?

eh_why_not2• 2 years ago

I'm reading up again to refresh my relativity knowledge. Though:

even though near the speed of light, more and more of that energy goes into higher mass and slower time?

This to me does not sound very different from saying the (relativistic) mass to be accelerated is larger, and is what's stopping a 1G (or any constant) acceleration to be maintained to bring the ship to the speed of light.

The concept may have been an overly simplified pedagogical tool though that I need to upgrade from. (I'll keep the comment chain intact since it's educational to me).

thrance• 2 years ago

The last time I studied special relativity was a while ago, but I think your mass only increases in other frames of reference.

If, for example, we consider the speed of your ship from the point of view of someone left on earth, then your ship should appear heavier from that person's perspective as you accelerate. But from your point of view, you still weigh the same, and so does your ship. In fact, you would see earth going through the dramatic "weight gain".

badosu• 2 years ago

The "increasing mass" stuff is more to make it easier for calculations and learning (with imo terrible consequence to physical intuition) than an actual physical concept.

This video does a good job talking about the issue: https://www.youtube.com/watch?v=6HlCfwEduqA

brap• 2 years ago

What does it mean that I’m “looking at the big bang”?

ermir• 2 years ago

Normally the light of the big bang is too dim (frequency too low) to be seen, but if you travel really fast the blue shift effect will make it visible, and since this light is uniformly distributed in the sky, it will appear as while light everywhere.

mike_hock• 2 years ago

What happens when you accelerate to a speed at which a photon with a wavelength as large as the observable universe (in the world frame) gets blueshifted to a wavelength shorter than the Plank length in your frame of reference?

mlsu• 2 years ago

I accelerated to 100%c, but then nothing happened. It seemed like no time passed and I didn't go anywhere. Someone help?

moffkalast• 2 years ago

The universe police will be along shortly to mutate you into a large salamander. Them's the rules.

FergusArgyll• 2 years ago

meh heh heh heh :)

jprd• 2 years ago

So much of my life has been reading sci-fi that was perhaps before my time, but oddly prescient, and I think in some ways, self-deterministic.

I know (enough) about the math and physics, the energy required, etc. to logically understand how "impossible" it might be.

My brain still rebels and to some extent, wants to believe.

CapitalistCartr• 2 years ago

At relativistic speed, atmospheric braking would improve the ship into a cloud of plasma.

savef• 2 years ago

I don't care so much about the physics side, it's just so bloody pretty. Is there anything like this that will play infinitely, with similar sliders to tweak the visuals? It'll look so good on an OLED.

nolroz• 2 years ago

According to another comment The author published a few games which include the code this is based off check out "the polynomial" on steam

davelondon• 2 years ago

I find it preposterous that we say that nothing can travel faster than light, when clearly that isn't the case.

zamadatix4• 2 years ago

Beyond that it's shorthand for "speed of light in a vacuum", care to enlighten on the clear cases?

dave333• 2 years ago

Maybe if you could start by persuading a small black hole to go where you want and following in its wake (or lack of wake actually). The black hole swallows everything in your path and grows more powerful. Perhaps if you had an array of three or more black holes you could steer the group by differentially feeding them somehow. If the initial black hole were an orbiting pair your spaceship could orbit a lagrange point and be swept along.

zamadatix4• 2 years ago

Black holes aren't immune to the effects of gravity from other objects just because they're black holes. It'd be no different than trying to use a trio of stars as your gravity engine (well, more space efficient). I.e. you still have to accelerate the stars, you still have to deal with slower things the stars "eat" slowing them down, if the stars pull your ship it's slowing them down. Effectively, you've just increased the mass of your spaceship by however much mass the black holes have and then still had to find something to accelerate the whole lot instead of your spaceship.

jxy• 2 years ago

Humans are humble. We only ride our star in about 200 km/s so we can take the scenery route. It takes mere 100 million earth years to get to the other side of our galaxy.

It's not very clear where our black hole in the center of the milky way is taking us though.

Aachen• 2 years ago

It doesn't run in my browser and I want to thank the author for giving a proper error message! So often, pages just break for various reasons and you're just sitting there "is it gonna load?" or "is this what I'm supposed to be seeing?"

This is the first time I see "xyz is not supported", which both helps me understand what's wrong and lets me switch to a popular browser to see the content. And the site works and looks great there (on mobile)! Thanks OP :)

goodmattg• 2 years ago

This is a stellar project

sriku• 2 years ago

The viz shows visible light, but you'll be basking in gamma and more energetic photons as they've all shifted up. It does note that infra red shifts into visible light. I wa swondering whether the perspective change is accurate as the length contraction should've brought everything much closer.

ge96• 2 years ago

man that shimmer is cool

user261• 2 years ago

Recently I saw this video explaining an other weird phenomenon of relativity. Simultaneous events aren't really simultaneous in all frames of references https://youtu.be/YAmHAKdyV1o?si=JXkv2AvCIrYN9ZdZ

username923409• 2 years ago

I had fun with setting the "throttle_value" variable to something insane, like 30 (1 is the max on the slider), to see how close to c you need to travel at for the web app itself to disintegrate.

Apparently, it takes just over two lines of "9"s on a 1920px display for this to happen. The speed wraps back around to zero, and the world time becomes NaN as an added bonus for (nearly) breaking the laws of physics.

mmmmmbop• 2 years ago

just over two lines of "9"s on a 1920px display

I love this unit of measurement.

xenophonf• 2 years ago

FYI, this doesn't work in Firefox, only Chromium. :/

CaptainFever• 2 years ago

It worked for me with Firefox Android.

imp0cat• 2 years ago

Works fine in FF for me.

tzs• 2 years ago

It's the aberration effects that were the most unintuitive for me. Specifically the difference when you are looking straight ahead in your direction of travel in how the stars appear to move when you are moving at constant speed and when you are accelerating.

At constant speed when a distant star first appears it moves directly away from the center point. When accelerating distant stars first move toward the center point then move away.

If you constantly increase the acceleration you can hold a star that is not at the center point stationary for a while, which is totally not something I would have expected.

I'd like to see something like this except instead of a seemingly random assortment of stars the stars are on a regular grid, connected by glowing filaments along the grid lines. That would make it easier to see what the heck is going on.

h45x1• 2 years ago

[Show HN] Admittedly much less visually engaging :), but some time back I was interested in the twin paradox, so I made a website where you fly a toyish spaceship between three stars and see how the various clocks and the space itself change. It's flat spacetime, so relatively easy to simulate and everything just runs in JS: https://twinparadox.org

The original motivation was, can one make a game with relativistic spaceships, conceptually speaking? The issue is that if a player calls another player IRL it'll be like instantaneous communication... In flat spacetime, though contradictory to its postulates, one can choose a preferred frame of reference, say the planets, and allow instantaneous communication within that plane, not leading to any inconsistencies in a game, I think. Curved spacetime doesn't admit a notion of simultaneity, so that's completely out, no black holes in a game :( Never really got to the point of modelling multiple ships though, the life caught up. So it's just a single ship on the website for the moment.

dcanelhas• 2 years ago

In case you're interested in these kinds of relativistic effects, there is a toolkit called OpenRelativity http://gamelab.mit.edu/research/openrelativity/ that you can use, for your simulated near-luminal speed graphics.

It's used by the (free) game "A Slower Speed of Light". http://gamelab.mit.edu/games/a-slower-speed-of-light/

euroderf• 2 years ago

Let's face facts: The spice must flow.

noduerme3• 2 years ago

So, this does seem to take the angle I'm flying at into account. If I'm accelerating to 99.9% the speed of light, and I yaw 180deg the view, I start "decelerating".

What happens if I keep maximum acceleration and pitch up 90deg? The software seems to keep flying on the original vector. Is this a bug or is it intended to be a simulation of how light would behave under those circumstances?

mihaaly3• 2 years ago

Not the way I see it. If I accelerate modestly (0.2m/s2) to just above 30% of c where the movement is noticable enough and then put the direction of travel just beyond one of the corners (e.g. just beyond the top right) by turning the view then the direction of travel will move slowly towards the center of the screen on its own - giving a slight sense of turning in the beginning - as one would expect of current velocity vector and the velocity accummulated from acceleration vector (always towards the center) add up. At velocities close to c the already huge velocity vector dominates and no chance of perpendicular (or any angled) acceleration make any effect on the velocity vector direction: the diagonal of the two can never go beyond c. The velocity vector locks in. (probably why those traveling near the speed of light don't age much, their particles cannot interact that freely with each other when their movement is locked in to a common travel vector?).

And here I'd observe that the acceleration value is measured in the local system where time slows down relative to the observer's system, while the speed is measured in the observer's system (naturaly, my speed relative to me is always zero).

noduerme3• 2 years ago

> the diagonal of the two can never go beyond c

Sure, from the observer's system (home planet "stationary" the speed is measured from) it can't go faster than c... but that's where I don't think it's accurate. From the flyer's perspective, if you're close to c (as viewed from home) and suddenly accelerate at a 90deg angle, that shouldn't bleed off your speed forward, or be limited by your speed forward. Only from the distant viewer's perspective would those two velocities combined max out at c. From your perspective they wouldn't.

jonplackett• 2 years ago

Am I the only one disappointed this isn’t a link to a real relativistic spaceship?

584fe345df56• 2 years ago

I sometimes wonder whether at some time in the future we will discover a piece of physics that will make things like this real.

bocytron• 2 years ago

Now you are staring into the big bang in all its glory; make sure to wear safety squints.

Wait what? That's not true right? All the light we see is concentrated in one point but it's not really the big bang that we see, it's an illusion, is that correct?

nurumaik• 2 years ago

It's blue-shifted microwave radiation from big bang. You see it in one point because doppler effect is directional

ivolimmen• 2 years ago

Nice visualization except for the fact that traveling backwards does not show anything...

taneq2• 2 years ago

That’s what the brightness slider is for.

boxed• 2 years ago

Isn't that correct though? The light gets redshifted away from the visible spectrum quite fast and after not very long there's nothing to see. Unlike when going forward where there's plenty of extreme red light that can be blueshifted into the visible spectrum (and eventually past it).

crispyambulance• 2 years ago

I think it's perhaps better to abandon ideas about going at high relativistic speeds to bridge large distances.

There's a more practical idea in nature: become a seed. It's how living things traverse vast distances and overcome intractable resource constraints during transit.

Compact oneself into an inert crystalized form, aim rocket, launch, wait. All you've gotta do is prevent chemical/structural breakdown for a few millennia or eons. Upon arrival to destination, have a machine turn-on and reconstitute the body and voila, you're there, all refreshed and ready to explore and virtually no time has passed.

Of course to do that one would have had to master biology, or maybe skip biology entirely and opt to copy oneself into a machine format, but that is likely easier than travelling at a sizeable fraction of c?

gassi• 2 years ago

If you're not seeing the stars in Firefox (the background is all black), turn off "Enhanced Tracking Protection".

nsxwolf• 2 years ago

I gunned it, got up for coffee, and came back 200 years later having traveled over 6 million light years.

I am now in the galaxy NGC 300, very similar to the Milky Way.

Everyone I ever knew is gone.

I am sad and alone.

AnonHP• 2 years ago

I kept getting closer and closer to the speed of light, but before I crossed even 2 million light years (I think), I was staring at the Big Bang. Then I remembered that the diameter of the observable universe is about 90 billion light years (give or take), and I realized that I’m not going to be able to reach one end anywhere. There’s nothing that makes everything seem so small and insignificant like astronomy.

RGamma• 2 years ago

Pff, this is cool and all, but Big Rigs trucks go much faster: https://www.youtube.com/watch?v=R8X7Vj6JXPk

Will the universe also say "You Win" when you hit the speed of light?

LorenPechtel7• 2 years ago

Can anyone explain what is happening as you get a few nines in your velocity?

Yes, that's the microwave background being blueshifted, but why is it growing across the screen? Shouldn't the angle that's blueshifted be less and less as you go faster? At lower speeds we do see the starbow effect, passing stars going down the spectrum as the angle increases.

And what becomes of the stars as you're going fast enough? Yes, most of the energy is shifted out of view but don't stars emit some at such low energies?

raattgift4• 2 years ago

These are good questions, but the answer is essentially "not in scope for this visualization". And, also, really hard to visualize with reasonably correct physics at higher "nines".

The tool does not deal with gravitation. We know that our local patch of the Milky Way (out to a few hundred lightyears) is full of kHz-Hz waves (LIGO, Virgo et al.), and nHz waves (pulsar timing arrays). Known sources at these frequencies are extragalactic, so there will be lots of these waves outside the Milky Way too. At significant boosts, these gravitational waves will impose visual distortions. The "twinkling" that pulsar timing arrays detect over the course of many months would be detectable over the course of much shorter periods of ship time.

Gravitational microlensing is likely to create uncomfortably hot spots (low-energy caustics from our usual point of view) for an ultraboosted spaceship.

We also strongly suspect there are lots and lots of black holes massive enough to impose a significant gravitational redshift on background light from the early universe, releasing far IR radiation from near the photon sphere (note, this isn't Hawking radiation, just delayed and redshifted background) that an ultraboosted observer should be able to spot.

(Work in this area is usually about considering what an ultraboosted massive particle does as it passes a massive observer. For example, in the 1970s the Aichelburg-Sexl ultraboost tried to capture what a neutral cosmic ray would do -- gravitationally -- to a spherical gas cloud along its path. In essence there is an exchange of momentum: the ultraboosted particle loses some, and small parts of the gas cloud gains some. Increasing the mass and structural complexity of the ultraboosted observer inevitably runs into inelasticities. That admits a hand-wavy expectation that even below the threshold at which subatomic physics of the ship becomes relevant, the ultraboosted spaceship is liable to become so very hot that its thermal spectrum masks practically all the light from everything ahead of it.)

As you raised in your final question, there is good reason to believe there is plenty of very deep IR electromagnetic radiation out there from all sorts of sources. Most models of cosmic inflation will produce gravitational and electromagnetic radiation with all manner of wavelengths, many of which are stretched to cosmological lengths. We don't really have a good view of any of that because presently we can't yet make a sufficiently cold ultra-long-wavelength (sub-30 MHz; cf. FARSIDE, LCRT, GO-LoW) detector and don't even have good ideas about how to look at astrophysical sources below kHz. There's probably lots of bodies (e.g. magnetic interactions with exoplanet atmospheres and gas clouds) that will become optically bright as the CMBR is blueshifted out of the range of human vision.

The visualization also does not offer up a physical observer who would feel variations in the galactic magnetic field (cf. the Sokolov-Ternov effect with enough "nines"), the cosmic neutrino background, and two-photon physics from ultraboosted CMBR and starlight interacting with the observer's photon shock front.

The visualization is pretty, it captures some gross aspects of being relativistically boosted, but as many scattered threads in the discussion discuss, it's probably not a useful hint about what one of our descendants might experience if somehow they could reach "a few nines".

LorenPechtel7• 2 years ago

This doesn't address the biggest question I had--why the CMB grows across the screen rather than shrinking into a searing point ahead.

Relativistic Spaceship

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