Space Elevator

1151 pointsposted 13 hours ago
by kaonwarb
(neal.fun)

244 Comments

jvanderbot

4 hours ago

Very cool. One thing I wish was better shown: space is close, it's just hard to go up. Our liveable breathable atmosphere is razor thin compared to the size of earth.

In most cases, 100km is less than the distance between sizeable metropolitan areas. It's a day long bike ride. Air runs out less than a bus ride across town. A 15k jog/hike would put you in the stratosphere. Those jet aircraft that seem so high are closer than that. Closer than your friends house or the local stadium probably.

Look at a map or globe with that in mind and everything feels so thin!

amflare

24 minutes ago

For a standard globe that you might see in a classroom, the Earth's atmosphere is about as thick as the paper glued to the outside that displays the map.

messe

4 hours ago

> it's just hard to go up

Going up is the comparatively easy part, it's not exactly rocket science. Going fast enough sideways so you stay up there is the tricky bit.

aDyslecticCrow

4 hours ago

> Going fast enough sideways so you stay up there is the tricky bit.

nah, thats the simple part. getting up there efficiently is the difficulty. once we're up, its just a matter of force over time to create a nice orbit.

The faster you go, the more friction you face, and the more heat and vibration your equipment must endure.

Going slower reduce friction and stress but use more energy just negating gravity. Slow rocket is inefficient rocket.

So we wanna leave the atmosphere as soon as possible, but not so fast that the rocket melts or engines collapse. Prefferably just below the sound barrier.

once we're up, its pretty chill... until you wanna go down again. Slow rocket is alive rocket.

advisedwang

39 minutes ago

Energy for 1kg to reach LEO (800km * 1kg * 9.8m/s2) ~ 8MJ

Energy to reach LEO velocity ~ (1/2 * 1kg * (8km/s)^2) ~ 32MJ

nroets

11 minutes ago

The rocket fuel needed to produce that 40 MJ weighs close to 1 kg, especially when you include the oxidiser. So the energy needed to accelerate 1kg of payload to LEO velocity is much more.

literalAardvark

an hour ago

It's not that simple though. The rocket equation still applies so it's almost as hard to do (you just get rid of atmospheric drag), and failed launches are also extra catastrophic.

Even more, your delta v required is still huge. I can't be bothered to run the numbers right now but most of the delta v is in the orbital velocity, not in the altitude.

raducu

3 hours ago

> once we're up, its just a matter of force over time to create a nice orbit.

It depends what you mean by "up there". ChatGpt tells me you'd free fall from 1000 km to 100km in about 8 minutes. It also did the math that you'd need 1.65G of sideways thrust to reach orbital speed. That's quite a bit of force for spacecraft sized objects.

If you have an actual space elevator, sure, you can go to close to geosynchronous altitude and by that time you'd have enormous sideways velocity just by being dragged sideways by space elevator and indeed it would be easy to propel yourself to orbit (above a certain altitude my intuition tells me you could let go of the rope and while you'd end up on an eliptise you'd still be in orbit)

hermitcrab

2 hours ago

>ChatGpt tells me you'd free fall from 1000 km to 100km in about 8 minutes

You trusted an LLM to do the maths when it is just s = 5t^2?

block_dagger

33 minutes ago

It's NOT rocket science?

Retric

31 minutes ago

You can reach space using air breathing jets. You can’t stay in space using air breathing jets.

Pxtl

3 hours ago

Which is another part of why a space elevator is nifty - by definition it extends out to a distance where you are going fast-enough-sideways.

Now, I have no idea how practical it is to build one (Angela Collier has a video saying it's kinda ridiculous), but it's a cool idea.

https://www.youtube.com/watch?v=Z5aHMB4Tje4

Also since rockets have moved away from hydrolox, it would be nice to have a greener launching system.

raducu

3 hours ago

> Angela Collier has a video saying it's kinda ridiculous.

There are other concepts like space fountains, orbital rings and sky hooks that seem more doable -- especially the sky hook seems close to do-able, especially on the Moon.

lurquer

34 minutes ago

> it's just hard to go up.

Eh. Going up is easy. A Frenchman, a sheep, duck, and rooster solved the whole ‘up’ thing over two centuries ago.

But going DOWN? That’s far more difficult. What wonders may lie beneath our feet: vast caverns, ore, underground oceans… hard to get to though.

Liftyee

33 minutes ago

True statement, but disclaimer: your friends may be closer if you live in a European city without American suburban sprawl...

kmacdough

8 minutes ago

Super fun!

I do always have to object to comments like "space elevators are possible," "scientists have studied" and "would save money".

It's a fun thought experiment, nothing more (for now). You can do some calculus to estimate the necessary strength-to-weight ratio based on centripetal and gravitational forces. Single carbon fibers seem to meet this optimistic criteria.

But there are many forces left out. Many practicalitites left unconsidered. Why? Because there is no scientific community that believes it's vaguely achievable with near-future technology. It's simply not worth investing the outrageous resources required to do a vaguely useful viability analysis.

simpaticoder

9 minutes ago

Given the title "Space Elevator" I was expecting some more information on a hypothetical space elevator cable. Assuming humans can manufacture defect-free nanotubes at any length and can combine them into thicker cables, you could specify at every height a) the cumulative mass of the cable, b) the thickness of the cable at that point, and c) the stress experienced by the cable at that point. You could further break c down into the gravitational vs centripetal forces on the cable at that point.

dpq

8 hours ago

Amazing work! One minor correction:

> As particles from the sun hit the atmosphere, they excite the atoms in the air. These excited atoms start to glow, creating brilliant displays of light called auroras.

The process is a bit more nuanced than that. The modern mainstream understanding is that the growing pressure of the solar wind makes the tail of the magnetosphere "contract" (sort of pushing it inwards from the sides), which leads to reconnection of magnetic field lines. Once the reconnection occurs, the magnetic field lines that remain bound to the geomagnetic dipole accelerate the particles on them towards the Earth => they slam into the atmosphere, exciting the atoms and generating the aurora.

hwillis

5 hours ago

Any discussion of aurora which do not mention space tornados: https://en.wikipedia.org/wiki/Space_tornado

Is inherently incomplete. Not necessarily because they're needed to explain it, but they do need to be brought up at any time possible because they're cool.

pfdietz

6 hours ago

Right. So the solar wind provides the energy that drives the aurora, but it's more indirect than just "solar wind particles hit the atmosphere". Instead, the solar wind is injecting energy into the magnetic field of the magnetosphere, and when reconnection occurs some of this magnetic energy is dumped into particles in the magnetosphere, some of which can then strike the atmosphere.

GMoromisato

an hour ago

I love this page and I donated, but I was (naively) expecting it to get to geosynchronous altitude, which is the actual top of a space elevator.

Of course, that would require a page 420 times longer, and I don't know if a browser would even support it.

kmacdough

3 minutes ago

I mean the idea isn't actually real or practical. It's a thought experiment that makes for some fun calculus. No one's actually going to try and build one.

daniel_iversen

11 hours ago

This was incredible! Couldn't stop scrolling and reading. For a kid of a certain age and curiosity it'll blow their mind! I'm so grateful the creator made this, shame that his "buy me a coffee" isn't a simple PayPal or Apple Pay but you have to put in credit card or bank details!!

anticrymactic

7 hours ago

PayPal and Apple pay take a significant cut of the transaction. CC is a lot less and bank is mostly free of TX fees. Most users don't know/don't care, so given the option, they will likely take it and funnel their donations to conglomerates.

blueg3

5 hours ago

PayPal doesn't cost significantly more than what a small online place can get from other payment processors. It's something like 3% + $0.50. That's also not much more than what a small business can usually get for in person credit cards.

This site does use buymeacoffee.com, which appears to be a dedicated payment platform. Its transaction fee is apparently 5%, which is steeper, but better for these small donations because of the lack of a fixed fee.

jve

6 hours ago

I don't like to input Cc details into random sites whose main business is processing said transactions.

linsomniac

6 hours ago

Maybe you'd like one of the banks that provides you with limited-use or one-time credit cards? I've been using one called Envelope Budgeting for the last few months after my previous one shut down. It's $40/year, but that's waived if you spend more than $5,000 USD in card purchases. I put the Neal.fun on my "Misc" card that I keep at $0 balance and transfer money to when I buy something.

I believe there are other services that will also give you virtual cards, I'm not familiar with them off hand.

https://envelopebudgeting.com/

dmd

5 hours ago

I'm not understanding this sentiment at all. You'd rather input your CC details into a site whose main business isn't dealing safely with credit cards - rather than inputting it into Stripe (which is what his site uses), whose entire raison d'etre is doing so?

jve

4 hours ago

Sorry, I got the expression wrong. You must inverse the logic :)

mbirth

5 hours ago

But xx% of some amount is still better than 100% of $0. And the pure convenience of using PayPal, Apple Pay or things like Ko-Fi will probably result in more net donations.

ddoolin

4 hours ago

How do you pay with PayPal if not putting in your credit card or bank details? link is a pretty well-known online wallet and much simpler to use than PayPal.

sojournerc

3 hours ago

I've never heard of link, so it's the difference between a random website and a well established brand. Not that hard to understand why someone might be hesitant to put in their cc details.

tempestn

11 hours ago

TIL it's estimated that over 48 tons of meteors hit the atmosphere every day.

Regarding actual space elevators though, while they're not sci-fi to the extent of something like FTL travel - ie. they're technically not physically impossible - they're still pretty firmly in the realm of sci-fi. We don't have anything close to a cable that could sustain its own weight, let alone that of whatever is being elevated. Plus, how do you stabilize the cable and lifter in the atmosphere?

A space elevator on the moon is much more feasible: less gravity, slow rotation, no atmosphere, less dangerous debris. But it's also much less useful.

tsimionescu

8 hours ago

While a space elevator doesn't contradict any fundamental limits of physics, that doesn't mean it's actually possible to build one. There is no reason to be certain that it's actually possible to create a material that has the required characteristics in terms of tensile strength to support it's own weight, plus the weight of the elevator, plus the weight of all the additional cabling. It also has to endure the huge temperature differences that it will experience along its length and from day to night and from season to season.

This is especially true considering that you don't need something that barely holds - you need something that you know will hold up to many times more weight than it needs to, so that it can be safe: the potential energy such a thing would store would be enough to dig into hundreds of meters of rock all around the world, if it ever crashed. So, you have to ensure there is no realistic chance of it ever crashing. It also has to be highly non-fragile in other ways, so that a madman with a bomb or a freak collision with an airplane or a meteor (especially likely in the thin upper layers of the atmosphere) won't bring it all down.

This combination of properties may well be completely impossible to actually achieve in a material. Even if there is no obvious basic law of physics that it would break, that doesn't mean that it wouldn't break other, harder to touch, derived laws.

Jolter

8 hours ago

A terrorist attack on a space elevator happens to figure in the first episode of the TV series Foundation.

https://foundation.fandom.com/wiki/Bombing_of_the_Star_Bridg...

It’s about as devastating as you would expect.

Frotag

4 hours ago

Terrorists-attacking-elevator is something that comes up multiple times in Gundam 00. Probably as an allusion to 9/11 (resistance to a growing superpower), but the in-universe explanations are pretty interesting too.

The elevators were developed for cheap space travel but unsurprisingly centralized the world's economic development around the owner countries. ie the other countries became increasingly reliant on them and the world segmented into (three) blocs. But the owner countries became increasingly protective / paranoid, leading to cold-war era developments where each of them secretly researched fancy space weapons and stockpiled more and more military assets around the elevators.

So some of the attacks were by poorer countries lashing out. Some attacks were to expose the military assets being hidden in the elevator (outlawed by intl treaty). Though most were probably just excuses to show things like giant robots vs death star.

lproven

7 hours ago

That's odd. The first episode was the only one I watched and I don't remember that bit. It might have grabbed me.

A terrorist attack on a space elevator is a pivotal plot point in Blue Mars by Kim Stanley Robinson, which IMHO is a better work in basically every way than Asimov's magnum opus.

CaptainOfCoit

6 hours ago

> That's odd. The first episode was the only one I watched and I don't remember that bit. It might have grabbed me.

I think it's the first episode of season 2 or 3, not the first season. I remember someone else mentioning it, but I've only seen season 1 and don't recall that either.

mechanicum

4 hours ago

Definitely S01E01, @ ~55-58 minutes. I just watched it.

lproven

4 hours ago

Huh. OK then. I was not taken by it and don't really want to watch it again, or the whole thing, so I will take your word.

Metacelsus

6 hours ago

Doesn't the space elevator attack happen in Red Mars not Blue Mars?

p_l

5 hours ago

There's a terrorist attack, sorta, in latter book, but Red Mars was admittedly a legitimate military strike, as was destruction of Phobos.

icetank

7 hours ago

The issue of the line falling back to earth is solved by putting the base of the elevator on water. If the top part of the elevator was cut of you could even detonate charges along the line to make sure all pieces fall into water.

0xEF

7 hours ago

Are we to assume they would be falling straight down? Because I'm pretty sure that's wrong. I'm not a physicist, though, and am happy to be corrected because every time the Space Elevator comes up, I want to know what happens when catastrophic failure occurs and how we'd mitigate that.

speed_spread

6 hours ago

It would become a giant whip falling faster and faster round the equator.

mr_toad

6 hours ago

A space elevator on Earth would be over 35,000 kilometres long. Depending where it broke it could wrap halfway around the Earth.

kqr

5 hours ago

At first I was confused by this because the Kármán line is less than a percent of Earth's circumference up, but then I realised we're probably talking a geostationary anchor or something, which is very nearly a circumference up.

tsimionescu

4 hours ago

Yes, you need a geostationary orbit for the tether, otherwise it would either fall down or spiral away with time.

pfdietz

6 hours ago

There's also the issue of the vehicle on the space elevator falling back to Earth if it detaches from the space elevator (accidentally or deliberately in case of malfunction that stops it from moving up). This means each vehicle will need rockets on it. At low altitude, the rockets are fired to keep the vehicle from reentering the atmosphere too fast at a steep angle, killing the passengers. At high altitude, the rockets fire to raise the perigee enough that the vehicle misses the atmosphere entirely (or enters at a very shallow survivable angle). There's a cross over point that dictates the delta V the rocket must be able to deliver. which if I vaguely recall correctly is greater than 4 km/s.

Pure payload capsules with no passengers wouldn't need this.

The argument for space elevators is that there's a pretty strong limit on how much payload can be launched by rockets due to injection of water into the upper atmosphere. Starship could arguably reach this limit with plausible projected growth rates in traffic.

actionfromafar

5 hours ago

Why is the water bad?

pfdietz

3 hours ago

In the stratosphere it both contributes to IR opacity, increasing global warming, and can provide ice surfaces on which ozone destruction is amplified. The stratosphere is normally extremely dry, so even small inputs can have an effect that would be invisible in the much moister troposphere.

pbmonster

9 hours ago

> A space elevator on the moon is much more feasible: less gravity, slow rotation

The slow rotation is a minus, it means you've got to string the tether up to L1 instead of "just" up to geo/luna-stationary orbit. A lunar space elevator needs to be at least 56000 km long, more than 20000 km longer than the one to earth.

> But it's also much less useful.

Yeah, especially because all the things that make lunar space elevators a little more attainable also make lunar mass drivers a lot more attainable. Why ride in an elevator for a week if you also can just be fired from a cannon?

tempestn

27 minutes ago

Ah, good catch. Stand corrected on that one.

lloeki

8 hours ago

Well if it's contingent to having massive amounts of unobtainium and subject to unsolvable engineering reality check conundrums then it's just as unlikely as an Alcubierre drive which "only" needs exotic matter that allows negative energy.

Yizahi

9 hours ago

The problem with space elevator is not only the lack of material today, but also the fact that such elevator is an ultimate and very fragile weapons platform, you basically get stones up the well and then drop them on the enemy. Meaning that any authoritarian country would destroy it even before it is ever built. And sturdy enough space elevator after it's break at any high point would start falling down on the planes in a loop, eventually flattening everything in its path when higher portions reach supersonic speeds. So unfortunately there is low chance it will be built, unless we sort out stuff on the planet first.

pbmonster

9 hours ago

I don't see it. Why worry about a weaponized space elevator when stealth bombers, cruise missiles and ICBMs exist?

If the power building the space elevator wants to bomb you, you're going to get bombed.

Yizahi

6 hours ago

Russia, China, Iran etc. are throwing a hissy fit whenever even a small weapons are deployed in the neighboring countries. USA too if we are being fair. They won't even wait for that opportunity.

pbmonster

5 hours ago

I think they mostly throw a fit because medium range ballistic missiles allow practically no useful early warning.

When the ICBMs go up, early warning radars notice them right away and you still have time to act. Leaders can make it to helicopters and basement bunkers, bomber squadrons can scramble, missile silos can already be empty when hit, road mobile ICBM launchers can still relocate.

But with a large enough number of MRBMs, your opponent might get ideas. They might start thinking about getting away with a decapitation strike.

The military space elevator is more like an ICBM in this case. There will be ample warning when somebody drops something from geostationary orbit (and also when somebody drops something from lower up).

sixQuarks

6 hours ago

The US throws the biggest hissy fit AND is the biggest hypocrite about it as well.

actionfromafar

5 hours ago

When the stakes are that high, words such as hypocrite don’t fit very well. It’s all game theory. It bought us Pax Americana for a while. Not universally loved but a time may (God forbid) come when it will be universally missed.

sekai

4 hours ago

> Russia, China, Iran etc. are throwing a hissy fit whenever even a small weapons are deployed in the neighboring countries

Because that's all they can do

tsimionescu

8 hours ago

The bigger problem I think is the elevator itself. Cutting it and letting it fall would be far more destructive than any weapon ever fired or even conceived.

pbmonster

8 hours ago

Probably no easy task.

Snipping off just the first few kilometers is not catastrophically destructive yet, and cutting it down further up would require multistage rocket designs, sophisticated steering/targeting and potentially significant yield (you'd need to cut unobtainium, after all...). If you can build a space elevator, you can defend against those.

You better thoroughly inspect what cargo you put on the elevator itself, of course.

tsimionescu

7 hours ago

Only if the material is way over provisioned. In general, the higher the intrinsic structural load is on a material, the easier it will be to destroy. So, to defend from these attacks, you not only need a cable that can support its own weight, plus the weight of the desired payload, plus some small-is extra tolerance. Instead, you probably need a cable that can support, say, twice its own weight plus four-five times the payload. Not to mention, now you don't only need excellent strength along the cable, but also across from it, and extreme heat resistance too (all of the strength is irrelevant if it's enough to coat some part of the cable in thermite and ignite it)

icetank

7 hours ago

You only need to defend the easy to reach parts. So the base and the cargo pod. To hit the upper parts you need advanced rockets and targeting systems.

tsimionescu

4 hours ago

Why advanced? It's a stationary target that's 35,000 km long. I don't think it would be that hard to hit.

Not to mention, securing the cargo would be an extremely difficult task in itself, especially when one of the main thinga you'd like to raise through the space elevators is rocket fuel.

vdqtp3

3 hours ago

> stationary target that's 35,000 km long

and what, 12" wide? 24"? that's still very difficult to target

Yizahi

6 hours ago

One nuke will kill any realistic sci-fi material. And guidance for those is a cheap and tested.

hermitcrab

23 minutes ago

Nukes are a lot less effective when there is little or no atmosphere to push on.

pbmonster

5 hours ago

Yeah, but then we're discussing opponents with nuclear arsenals and ICBM programs. Those opponents are generally reluctant to nuke stuff, or commit acts of war similar to nuking stuff.

But yes, a space elevator would be difficult to defend in World War III.

iberator

6 hours ago

Easy. You just blow the elevator FROM INSIDE. Plant some bomb into the elevator itself and while in half way BOOM!

pbmonster

5 hours ago

That's what the entire point about INSPECTING CARGO was about.

bob1029

8 hours ago

And hypersonic weapons. If you can get one to fly at Mach 20 for at least 10 minutes, you could cover the entire surface of the planet with a dozen launchers.

lnsru

9 hours ago

Space elevator was the perfect application for carbon nanotubes according my professor few decades ago. I wish humanity could unite for such project and enter space exploration phase. But I feel it will stay sci-fi forever.

tiagod

2 hours ago

Thing is, you're going to invest massive amounts of R&D in something that might be impossible, when you could invest in actually building stuff in space so you only need to shoot humans out there.

adwn

9 hours ago

Almost all discussions around space elevators focus on the cable itself, how to manufacture and deploy it, and completely forget about the issues that would arise afterwards:

1) How do you attach the climber to the cable without affecting its structural integrity? By squeezing it really hard? A material that's optimized for longitudinal tension strength is probably not very tolerant of lateral compression.

2) How do you provide power to the climber? A regular electric cable can't support its own weight, so either you have to attach it to the climbing cable, or you have to make it from the same material.

3) Is it even worth it? The climber needs to cover a distance of ~36,000 km, so even at 200 km/h it takes 7.5 days from the bottom to geosynchronous orbit. How many climbers and what payload can the cable support at the same time? Refer to issue #1 regarding limits in speed and mass per climber.

The throughput in tonnes/day is absolutely abysmal in relation to the immense upfront infrastructure cost per elevator. Compare this to SpaceX's Starship, which is getting closer and closer to fully reusable 100 tonnes to orbit in minutes. Space elevators will stay science fiction forever, not because they're infeasible, but because they're useless.

seer

an hour ago

If you somehow manage to get magnetic fields involved, so you are not afraid of friction with the cable itself, at 1.3 max apparent acceleration/deceleration (after a turnover) and including earth’s gravity you get 116min to geostationary.

If you account for various inefficiencies like taking it slow in the lower atmosphere Ant whatnot, it still should be in the matter of hours. So totally feasible and even comfortable.

fijiaarone

3 hours ago

Have you ever tried to balance a string on its end? It gets harder, the longer the string is. There aren’t any other physics than that.

hermitcrab

19 minutes ago

I think most plans envisage a large mass (such as a captured asteroid) in geostationary orbit to anchor the top of the elevator cable.

metalman

7 hours ago

thing is we do have materials strong enough, because as it turns out the issue with strength is in flaws between indivual molecules in any given material, not so much the type of material, and very small amples with perfect molecular bonds are plenty strong, but getting consistent perfect molecular bonds is the challenge, and if this can be done, other technologys ,such as vacume ballons will be possible, such as flying citys to go with the space rlevators

matt3210

11 hours ago

I love this guy.

Re playing this gem https://neal.fun/stimulation-clicker/

hakanito

3 hours ago

Thanks, I spent my lunch hour completing it without cheating. Amazing!

eMPee584

9 hours ago

Careful folks! This escalates quickly. Do not use xdotool on this.

dole

3 hours ago

Grateful it wasn't as long as Infinite Paperclips or Cookie Clicker, but still worth it. Great site!

moat

an hour ago

That was fantastic.

My biggest surprise (and confusion) was just how high butterflies and bumblebees go.

243423443

11 hours ago

I just clicked the temperature thingy in annoyance because I don't use Fahrenheit and to my delight, it just switched to Celcius

isolli

10 hours ago

Mine was automatically set to Celsius ;)

kqr

5 hours ago

I did the same. I eyed it suspiciously and thought to myself, "This site is really well designed. Do you think if I..." and it did switch! The obvious interaction was implemented! Rare these days.

cl0ckt0wer

3 hours ago

I watch AC's video on this, it was quite entertaining: https://www.youtube.com/watch?v=Z5aHMB4Tje4

If you like factory games and space elevators, then try Satisfactory!

Sohcahtoa82

an hour ago

I really wanted to enjoy Satisfactory, but I really struggled with building a factory in first person perspective.

Factorio, Dyson Sphere Program, Captain of Industry...loved them all. Satisfactory? Just wasn't for me.

cyode

10 hours ago

A beautifully executed project here, I bought Neal a coffee.

What evolutionary advantage, I wonder, is there to Ruppell's griffon vulture flying at 11400 meters?

edit: units

rkomorn

10 hours ago

Not every behavior has an evolutionary advantage.

If anything, "evolution" filters out disadvantages (eg: can't survive because your neck's too short and that pesky giraffe is eating all the leaves you could reach).

Evolution kills what doesn't work.

trinari

10 hours ago

but every behaviour has a cost. In cast of flight altitude its energy and distance to food, water, mating zones.

hatmanstack

9 hours ago

Darwin started with survival of the "fit". It changed to "fittest" in later editions.

robocat

5 hours ago

People focus on the wrong issue so most quotes about evolution are highly misleading: the keyword should be about reproducing. Survival is almost irrelevant. Darwin awards in particular should never be given to anyone with kids (unless they kill their kids too).

"Most grandkids" is good but not catchy.

Or Idiocracy "evolution began to favor those who reproduced the most".

rkomorn

4 hours ago

I agree to some extent but I don't think you can really separate the two. You have to survive long enough to reproduce enough. For almost all species, reproduction implies a non trivial amount of survival.

Edit: actually, "almost all species" is not right. Maybe "almost all interesting species"... which is admittedly too subjective a take.

rkomorn

10 hours ago

Having a cost and being too costly aren't the same thing though.

Cthulhu_

9 hours ago

Going up there's currents, going down... gravity. Sure it costs energy, but there's bound to be a tradeoff. Travel distance? Sight range?

iberator

10 hours ago

Feets are actually just fine in anything related to aviation.

delta_p_delta_x

9 hours ago

> Feets are actually just fine

Non-SI legacy units have been grandfathered in and 'accepted for common use', but ICAO recommends that SI units should be used[1] (eventually). China and quite the majority of the ex-USSR, for instance, use metre flight levels[2].

There have been at least two aviation accidents and incidents relating to unit mis-conversions. This is two too many. As an SI absolutist, everyone should switch to SI or units purely derived from SI (so domain-specific stuff like parsecs, electronvolts, and binary prefixes, if appropriately symbolled are OK). It is an internationally-recognised, and nearly universal standard that permeates every aspect of human lives.

[1]: https://aerosavvy.com/wp-content/uploads/2014/08/an05_cons.p...

[2]: https://en.wikipedia.org/wiki/Flight_level#People's_Republic...

actionfromafar

10 hours ago

I prefer to call them "footsies" or, sometimes "feet".

balamatom

5 hours ago

I think you've accidentally invented the antidote to the Imperial system: using diminutive/silly synonyms for units, and speaking in baby talk to people who insist on using it.

Unironically oughtta work better than that stuff with the barleycorns and fortnights.

actionfromafar

5 hours ago

Great idea! I’m for it. Be the change you want to see in the workplace!

hermitcrab

3 hours ago

>Above this altitude is known as the "death zone", because there isn't enough oxygen for human life.

Being pedantic, this should be "there isn't enough oxygen for sustained human life". An acclimatised climber can survive tens of hours.

isgb

5 hours ago

> Space elevators are actually a possible idea being considered by scientists. > The hard part is making a strong enough cable. And finding enough elevator music...

Most engineers would bring up a lot more issues than just finding a strong cable. Also, most attempts with e.g. carbon nanotubes have been abandoned ages ago https://www.newscientist.com/article/2093356-carbon-nanotube....

- We don't have a good ascent mechanism other than rockets - and then we might just use rockets without building an elevator. - We don't have a good (and safe) descent mechanism. - Maintenance? Protection from space debris? Protection from oscillations? Ground-protection if the elevator collapses?

This is dyson-sphere level of fiction. We can do back-of-the-napkin calcualtions on how things would work, but the practicalities make it completely impossible or impractical.

seanc

4 hours ago

Kim Stanley Robinson's description of a Martian space elevator falling and wrapping twice around the entire planet convinced me that they aren't a good idea.

https://www.kimstanleyrobinson.info/content/clarke

indoordin0saur

2 hours ago

A fictional representation of a thing exaggerated for dramatic effect and to create plot tension shouldn't really convince you of many things at all. They're rarely accurate portrayals.

ben_w

an hour ago

In adition to being fictional, what would happen on Mars does not reflect what would happen on Earth as the Martian atmosphere is so much thinner than ours.

enraged_camel

4 hours ago

A version of this also happens in the first season of Foundation, the Apple TV series based on Asimov's novels.

joenot443

3 hours ago

Would you recommend that show to the HN crowd? The books are super well liked around here, for good reason.

Apple's put out a staggering amount of content the last few years, I wasn't even aware this one debuted!

tw04

2 hours ago

I’ll give apparently a controversial take. The show is great. If you’re going into it expecting the books to be the guiding source material you’ll be severely disappointed. If you go into it assuming you’re watching a show that roughly takes high level concepts from the books but is its own thing and let it stand on its own, I think it’s worth watching.

georgeecollins

2 hours ago

I'm fine with series not following the books. But the show bugs me because it has great production values -- particularly the third season -- and great actors. But the writing and plotting is all over the place ranging to very bad. It is a bit dumb and always pretentious. It's the 70's version of Battlestar Galactica of our age.

senkora

an hour ago

This is the issue that I have with many Apple TV+ shows. The production value is always very high, but it has no correlation with whether the writing is actually good.

ajmurmann

2 hours ago

I also found the pacing to be inconsistent at best.

pavlov

2 hours ago

The Lee Pacing is consistently great though.

MengerSponge

2 hours ago

Lee Pace is great, and the "genetic empire" is a brilliant solution to a hard problem unique to television.

Brother Dawn: How often do we make this choice?

Demerzel: You always make this choice.

bananaflag

3 hours ago

Not the OP, but that show is a severely dumbed down adaptation of the books.

For example, each short story almost completely changes the cast (of course, with some descendants of characters appearing occasionally), as befits a saga that spans centuries. No producer was willing to run with that (as they didn't believe the audience smart enough to follow it would be big enough for the show to make a profit), so they introduced cryonics, clones, sorta-AIs (including robots out of their original context) to have some sort of continuing cast.

Also, the books have a quaint 1940s (NOT 1950s as people usually say it) atmosphere, with excitement about "atomic" energy (changed to "nuclear" in the 1950s publication), distant descendents of the slide rule, and generally weird-sounding math and science, that the show totally drops in favor of a "contemporary" feel.

And btw, the space elevator scene is lifted from Brin's Foundation's Triumph where it is described as a "future" event, part of Trantor's fall, predicted by Seldon's early team and trickled down to the general population.

rtkwe

3 hours ago

It's definitely got problems as an adaptation of the Foundation series where it turns one of it's biggest themes on it's head by making a few people like Gail super special and having the answer to the crises where the books were more about setting up groups and organizations so that they as a whole had an advantage or edge that would be the answer to the crises he forsaw. I think it's mainly due to them wanting to have the same people across multiple seasons where the books were free to throw away the whole cast each time. Setting up new characters is much more expensive in shows/movies than books where you can just say what someone's 'deal' is and give them internal monologues to setup their internality where shows can't usually get away with that.

I think separated from that there's a good enough show in there.

shagie

2 hours ago

> Also, the books have a quaint 1940s (NOT 1950s as people usually say it) atmosphere ...

    The next day’s hearings were entirely different. Hari Seldon and Gaal Dornick were alone with the Commission. They were seated at a table together, with scarcely a separation between the five judges and the two accused. They were even offered cigars from a box of iridescent plastic which had the appearance of water, endlessly flowing. The eyes were fooled into seeing the motion although the fingers reported it to be hard and dry.
If you've got a copy of the ebook, search for "cigar". The use of tobacco as a way to demonstrate luxuries beyond the regular is there.

In a recent re-reading of the series, I started having difficult with it in Second Foundation... and forced myself to finish Foundation's Edge. The amount of psionic ability and the... for lack of a better word "preaching" with the monologues was very much a science fiction of a different time.

Foundation (the TV series) had to do updates for modern audiences and media. I'm not sure if trying to remain perfectly faithful to the books would represent them well.

Foundation is a soft sci-fi about interactions between individuals and history and society. Trying to maintain the incidental harder parts of the written works that modern audiences expect to be somewhat consistent of far future technology with the 1950s lens on them would be quaint and a bit off-putting to people expecting future tech.

    He threw his cigar away and looked up at the outstretched Galaxy. “Back to oil and coal, are they?” he murmured—and what the rest of his thoughts were he kept to himself.
They took the major points, and wrote to follow the general path from one point to another given the expectations of an audience consuming it often for the first time - 80 years after the original was written... and given constraints of the format and continuity of actors (60 minute episodes rather than as a chapter of a short story in Campbell's Astounding Science Fiction).

jvanderbot

an hour ago

I long for a level of posthumanism that you can do things like smoke and drink for fun without any worry for long term health effects.

What at joy it'd be to fully experience life, not just a sanitized productized version, and have the safety net of perfect medicine to cure what ails ya.

Frotag

3 hours ago

> For example, each short story almost completely changes the cast (of course, with some descendants of characters appearing occasionally)

I wish directors were brave enough to kill off characters if it serves the plot. I get that there's IRL reasons that make it difficult (like contracts, scheduling, etc) but each new season accumulates more subplots to the point it's like a 30 minute episode is really a compilation of 3x 10-minute shows.

This bugs me in multiple-protagonist books too. Just feels like an excuse to pad the page count with introductions and cliff hangers every POV switch.

Frotag

3 hours ago

It's pretty and scratches that scifi itch. I've only read a little of the books but it's supposedly an entirely different story that coincidentally shares character names.

In terms of hardness, it probably on par with Expanse, so mostly technobabble with the magical tech only used when it's convenient for the plot. The abuse of "psychohistory" is particularly egregious. There's so many scenes where it's visualized a hologram of scribbles and they zoom in on more squiggles while divining the future.

But again it's pretty, so if you're okay with drama in space, it's maybe a 8/10.

hermitcrab

2 hours ago

It's about 45 years since I read the books, but the whole idea of being able to predict the future of human societies accurately with maths seems rather silly. Especially since chaos theory became mainstream.

lelandfe

3 hours ago

My friends who wanted an adaption of the series hated it.

My friends who like sci-fi enjoyed it.

It is regardless very striking and high budget.

Larrikin

3 hours ago

It's the best possible adaptation of the books as possible. They made some changes to allow for having main characters. In my opinion they also lighten the down side of the Mule story line and how the world works.

indoordin0saur

2 hours ago

I greatly enjoyed the first season (haven't seen the others) and I'm usually a curmudgeon when it comes to modern TV shows.

noir_lord

2 hours ago

I enjoyed the first season, for me the others aren’t remotely as good and I abandoned it halfway through the latest season.

kingkawn

2 hours ago

If you go into it looking for interesting sci-fi, especially the story of the Cleons, you’ll enjoy it. If you go into it looking for Asimov’s Foundation you’ll be disappointed

gilbetron

3 hours ago

The Mars one is much more interesting and traumatic :)

datadrivenangel

3 hours ago

Skyhooks may allow for much easier access to space within the limits of likely practical carbon nanotube based structures. A rotating tether that orbits the planet could be timed to 'catch and throw' supersonic aircraft into space. Lots of engineering still required, but potentially actually feasible compared to space elevators.

bombcar

4 hours ago

All we have to do is make the global religion require bringing a rock to a specific location; after long enough we’ll have a mountain so high it extends out of the atmosphere!

rigmarole

3 hours ago

Related and recommended: Greg Egan “Phoresis” a sci-fi novel of two twin planets in extreme proximity to each other. (I think I read it in one of his anthologies.)

hermitcrab

2 hours ago

To get to the Kármán line (100k) a mountain with a 60 degree slope would require a base of 115km. A cone with 115km diameter base has a volume of 3.5×10^5 km^3. Which is 3.5x10^14 m^3, which is about 10^15 kg of rock. So it is going to take you a while!

bombcar

32 minutes ago

3.5x10⁵ km³ you say?

1.08321×10¹² km³ is the volume of Earth, feasibility study done! Implement!

kubanczyk

4 hours ago

This presents a considerable risk of splitting English into several languages, none of them intelligible with the others.

notahacker

2 hours ago

The deity in question would also have to smite purveyors of LLM translation. This might of course not be considered a drawback...

SSLy

4 hours ago

have you ever been to Newcastle?

ben_w

an hour ago

Aye man, wey aye, went doon there worra bairn, didn’t ah? Cannae remember much like, was only a wee nipper at the time, knaa what ah mean? Me mam an’ da took us doon the Toon when ah was nowt but a little’un, like. Divvent really remember owt aboot it proper, but aye, been the once when ah was just a littl’ bairn, me. Proper yonks ago that was, pet!

(Translation: yes, once as a kid).

thijson

2 hours ago

I think a space elevator on the Moon would be more practical, pointing towards earth. The gravity force is smaller, so existing materials could work. There's not as much of an atmosphere to deal with. It would go past the L1 point between earth and the moon. It could be extended from the poles, where it's most likely where bases might exist.

mrkickling

5 hours ago

You didn't even mention the music!

Symmetry

2 hours ago

Impractical on Earth given existing technology, but there are a lot of bodies in the solar system which have enough gravity to make them worth while but where they're small enough that the materials needed are ones we have right now. The Moon in particular.

gizmo686

3 hours ago

Isn't the entire point of the space elevator to be the ascent/descent mechanism?

Once you have the cable up, you can grab onto it and pull yourself up.

bisby

2 hours ago

A space elevator doesnt just take you to the karman line (like in the OP website), to get to orbit, you'd need to get up to geostationary height. That's 22,000 miles.

What's the best way to pull yourself directly vertical along a cable for 22,000 miles?

What's the best way to descend 22,000 miles quickly, but also with a braking mechanism that isn't going to require a heat shield?

Some sort of slow cable car going at 10mph even is going to take 2200 hours... 1000mph is going to take 22 hours still. That's a full day to orbit even going REALLY fast. And getting up to 1000mph vertically, for a sustained 22 hours... that's not an easy feat.

And if the goal is just to get up past the karman line and use the elevator as a stage 1 for a rocket launch and detaching from the elevator while suborbital is fine, then it's a one way trip, and still need to re-enter the old fashion way.

The scale of space makes all of the problems far more complicated (edit: not just the cable strength issue, but traversing the cable)

notahacker

an hour ago

Unless we're using it for humans the transit time isn't that big a deal; "last mile" orbital transfer times are often measured in days anyway.

That "last mile" bit is going to entail independent propulsion anyway. Getting to the altitude if the ISS is a mere 10 hour trip at a sedately 40kph which isn't unpleasant even for humans, but the ISS orbits at nearly 29000kph (as will you if you let go of the space elevator at that altitude) and the velocities are only half as scary at the far end, so your rendezvous anywhere other than one specific point in geo is going to be complicated. But you've saved the fuel costs of escaping the earth's atmosphere that's rather significantly more than the fuel costs of other bits of your satellite mission, including reentry. (At least until the costs of building and maintaining and protecting the elevator are factored in, but who knows what unobtanium costs?)

oofbey

2 hours ago

You don’t need to get to geostationary to get to orbit. The reason elevators need to get that high is because that’s the lowest place you could “anchor” the top of the elevator to something fixed relative to the earth.

kingkawn

2 hours ago

Doesn’t the weight of the cable itself let alone any payload preclude this from becoming real based on all plausible material science

gizmo686

2 hours ago

It's more of the strength-to-weight ratio than just weight. But yes, there is no known material that would work as a cable for a space elevator.

michaelbuckbee

4 hours ago

In John Scalzi's Old Man's War, there is a discussion of how the more advanced society that they're interacting with deliberately put a space elevator on Earth, not because it was the easiest or cheapest solution, but as a sort of constant reminder of just how much more technologically sophisticated they were.

cmpb

3 hours ago

Really great book (and series). Though it's not "hard sci-fi" by any means, the technology feels real enough to keep my brain from focusing on the holes and enjoy the fun philosophical and ethical problems that Scalzi comes up with

shagie

3 hours ago

IIRC, it started out as a reimagining of Space Cadet by Heinlein but instead of the young it was with the old.

After the first book, he then goes to explore all the questions that it brought up. The question of identity (to me) seems like the most reoccurring question.

Btw, there's a new book in the series. The Shattering Peace was released in September.

reaperducer

2 hours ago

Most engineers would bring up a lot more issues than just finding a strong cable.

He did. The elevator music!

timonoko

10 hours ago

Giant Space Bola is much more attractive. It is a 10000 km string with capsules at both ends. It rotates in sync with earth so that the speed at meeting point is the same. You just hop in and end up in space without much effort. Because it is freely floating you can move it around to avoid meteor impacts and other such shit.

243423443

10 hours ago

Did you read Seveneves by Neal Stephenson? In the second part of the book, they use this and related technologies.

arethuza

9 hours ago

I think those technologies are mentioned throughout the book - just at a much larger scale in the second part.

daeken

5 hours ago

Bolos are used for spin gravity in the first part, but that's very different from the rotovators used in the second part. Both in concept and design. The key point with the rotovator is that the tip is moving at ~0m/s relative to the body it's orbiting when it's at its nadir, allowing you to just hop/grab on.

retube

11 hours ago

Was hoping would go to geostationary orbit as an actual space elevator would :)

Terr_

11 hours ago

Ditto, although you'd have to scroll about 357 times further.

I suppose it could be livened up by including the orbits of things, but there would still be lots and lots of empty space.

officehero

10 hours ago

Such a lost opportunity, was hoping for another "space is massive" experience like already done in similar interactive maps.

lolive

2 hours ago

Why not scroll up to 36000 kms, so we can reach the end of the cable? #iFeelCheated !

cranx

2 hours ago

This is cool, but the UX of the arrows should follow the scroll mode of the device. You drag down on an iPhone to scroll up. Following the arrow and dragging up causes nothing to happen

Aaargh20318

2 hours ago

This. Took me a while to realize you have to scroll down, not up.

hermitcrab

2 hours ago

This is a really nice piece of work.

Question: Why does the Douglas Skyrocket have its undercarriage down at 25km?

Unsolicited feedback: It would be nice to be able to click on an item and see some more information. Perhaps just a hyperlink to a wikipedia entry.

bilsbie

36 minutes ago

Why would cranes fly so high?

kinduff

12 hours ago

I always enjoy Neal's pages. I found planes at high altitude very interesting, didn't know we could fly that high!

lproven

4 hours ago

To quote Toy Story:

"That's not flying, that's just... falling with style!"

Accelerate upwards fast enough, you can so to speak fall upwards for a short while before you fall back down again...

chasingthewind

4 hours ago

I find it curious that the Lockheed Vega is chosen as “Amelia Earhart’s plane” since most people would probably associate her with the Lockheed Electra, the plane she was flying when she disappeared. It’s analogous to saying that Ernest Shackleton’s ship was the Nimrod…not wrong, just odd.

bentt

3 hours ago

Seems like even before we do an elevator, we should get _something_ tethered to the ground to be in space. Like... anything! That'd be a huge accomplishment.

vardump

10 hours ago

The rockets at higher altitudes were all in wrong orientation. In reality, they don't fly straight up.

nodra

2 hours ago

Just came to say that this is so cool. Great work.

cheraderama

3 hours ago

Doomscrolling isn't supposed to feel so right...

nunodonato

8 hours ago

Wow, I'm really surprised to see some birds flying that high. Question: How the heck are they able to live normally at such extremely low temperatures?

Zobat

5 hours ago

Interesting how counter intuitive it felt to scroll up from the "landing spot". Even with the instructions right there on the screen I tried scrolling down at first.

mikkupikku

an hour ago

> On June 21, 1972, Jean Boulet of France piloted an Aérospatiale SA 315B Lama helicopter to an absolute altitude record of 12.440 kilometres (40,814 ft).[68] At that extreme altitude, the engine flamed out and Boulet had to land the helicopter by breaking another record: the longest successful autorotation in history.[69]

I just had to look that up. Absolutely incredible.

hshdhdhehd

7 hours ago

Perfect. I think it just needs explanation of Karman line. Why is it 100km. What is the meaning?

0xEF

7 hours ago

It's my understanding that the Karman Line the conventionally accepted "edge" where you leave the atmosphere and enter outer space, but many call this out as a fairly arbitrary point, arguing that there is no measurable boundary. Useful as a point of reference for positioning, though. Neal possibly just used it as a marker but chose to not define it for this reason.

xipho

2 hours ago

Notes on mushroom clouds are sobering.

honkostani

7 hours ago

I missed that notice at where its says: Here be a near mars atmosphere in temperature, pressure (40 kms up) but not as hostile composition and with less radiation. Thats five Mt Everests high.

Oreb

6 hours ago

How do we know how high pterodactyls were flying?

flir

5 hours ago

Came here to ask the same thing. Hoping you get a response from an expert. I was vaguely under the impression they were mostly gliders... maybe it's something to do with thermals?

yreg

5 hours ago

The sound mixing is so smooth. Is it a simple fade with the right choice of melodies or is there more to it?

slrainka

6 hours ago

Wow, I just discovered Ruppell's Griffon Vultures from this. What a fascinating bird with high flying capabilities!

xrd

6 hours ago

My 8 and 10 year old daughters love this site, often choosing it over Roblox during screen time.

This is stunning and perfect.

avmich

5 hours ago

Space elevator is not something which stands on the ground and grows up. It is something which lives on geostationary orbit and grows down from it to the Earth. If you cut the lower 1 meter of it, the rest will hang...

...that is, until a satellite will hit the cable above. Space elevator is built in the equatorial plane, all satellites cross it, so eventually every satellite is going to collide with the cable. For this reason the space elevator is incompatible with existing spaceflight, that's why even with nanotubes it's unlikely to be built.

l5870uoo9y

9 hours ago

It is appreciated that you can change the temperature unit by clicking on it, and how surprisingly cold and changeable the temperature is as you travel up through the atomic sphere (down to -84C, -119F).

CaptainOfCoit

6 hours ago

Oh no, I scrolled all that way and didn't even reach some destination! Where does this space elevator go? No one knows! Would have been bit more satisfying if it ended up at a space station or something, as I think that's the purpose of the space elevator idea in the first place :)

matheusmoreira

6 hours ago

I think it could but does not necessarily have to reach a station. The elevator just has to clear the atmosphere, right? As they say: once you're in orbit, you're halfway to anywhere.

mrec

5 hours ago

There's a big difference between "clear of the atmosphere" or "100km up" and "in orbit". Orbit is more about velocity than altitude.

CaptainOfCoit

6 hours ago

> just clear the atmosphere

But for what purpose? You just want to float around in a elevator carriage, aren't you going somewhere when you go with a space elevator?

pharmhax

7 hours ago

Neat! It would be amazing to see how the pressure changes with altitude in addition to the temperature.

01HNNWZ0MV43FF

2 hours ago

Deep links would _kill_ on this. I'd love to be able to link someone to the Blackbird. (25,700 meters)

gherkinnn

8 hours ago

Amazing work as always. Paired with Wikipedia it makes for a very productive day.

whatsupdog

8 hours ago

No, thank you. Don't want any existential crisis today!

petesergeant

9 hours ago

Some huh! moments...

* Jeez, Everest is tall

* They got a plane to 17km in 1938!

* There was a paper airplane flight at 35km

dzonga

5 hours ago

does anyone have the link to the money one ? scale of a billion ?

asimovDev

5 hours ago

I didn't take a look cause I didn't see "reject all cookies" button in the cookie popup

TheDong

5 hours ago

Did you know if you open a page in a private browser window, once you close that page all the cookies vanish? It's even better than a button which might not even work.

asimovDev

5 hours ago

It's purely out of principle because in a proper cookie popup rejecting everything should take the same amount of clicks that accepting everything does

I do understand that this is one those generic ones (I saw it many times) which the original creator of the website just slapped on.

jmyeet

3 hours ago

Space elevators aren't going to happen. Not in Earth's gravity well anyway. Even if you can find a material strong enough (and that's a big "if"), you still have to traverse 50,000km to get from Earth's surface to geosynchronous orbit to get the benefit.

You know what does make way more sense and is way more achievable? Orbital rings [1].

Basically, put some copper wire in space, orbit it at ~8km/s, run a current through it and then you can reset structures on top of it (magnetically) and those structures are fixed to the Earth's surface. You can technically run a cable from 100-150km up to the surface and run a gondola into LEO. This would transform both Earth transport and interplanetary travel. You accelerate something on the inside (Earthside) of the ring at ~2G, like with a maglev train, and you have enough velocity to escape the Solar System.

[1]: https://www.youtube.com/watch?v=LMbI6sk-62E

stared

8 hours ago

How on Earth do we know the maximal altitude for a pterodactyl?

ai-onehealth

11 hours ago

Excellent! My wrist started to hurt 0.01% of the way to the moon.

neuronic

6 hours ago

Congrats, first time I noticeably hear my MBP M4 Pro fans and can feel the temperature through the keyboard.

Amazing work, as always. I love neal.fun

Edit: also good to know that paper airplanes have officially beat the SR-71, F-104 or X-43B with altitude record.

mrec

5 hours ago

I dunno, by that rationale you could argue that Tesla Roadsters have officially beaten the X-43B's altitude record, couldn't you?

_def

11 hours ago

The atmosphere of this reminded me of the game Outer Wilds

Physkal

10 hours ago

I was really disappointed not to see a sequel. No new games from the developers since.

Cthulhu_

9 hours ago

Its development is really interesting, in that it was more a proof of a scientific paper to start with. Anyway one of their tweets from September 2024 indicates they're working on a sequel, despite their publisher (Annapurna, owned by Megan Ellison, daughter of Larry Ellison) having had some issues around then.

nunodonato

9 hours ago

they are working on a new game. Outer Wilds doesn't need a sequel, leave it be, its perfect as it is ::)

FailMore

6 hours ago

So great. Thank you Neal!

tetris11

6 hours ago

> Temperatures can reach <something very high> but the molecules are spread sobfar apart you wouldn't feel it.

Conceptually I get, it's like being in a cold room that showers hot sparks on you from above occasionally...

...but I feel that the definition of temperature has been abused here slightly

everyone

9 hours ago

An actual space elevator would need to be over 357 times longer though right?

Awesome site!

TiredOfLife

5 hours ago

I like the white text on white backgroud. Makes very easy to read

tstrimple

10 hours ago

I loved the visuals but space elevators are far more science-fantasy than hard science-fiction. We should move on to sci-fi tech that has more realistic applications.

jaggederest

9 hours ago

Only for Earth. We already have materials that can do it on the Moon (Zylon, for example), though not with great tether-to-payload ratios (200:1 or more), and Mars isn't too huge of a stretch (huge like the mass of the tether, which would be in the thousands to one tether-to-payload ratio. Shipping 50,000 tons of Zylon to Mars is a different beast)

pandemic_region

5 hours ago

That space elevator music 100% made my day, thank you!

orangebread

6 hours ago

WARNING: This guy's site is a trap for people with ADHD/OCD -- the ease at which I was sucked into every link on his site made me nope the heck out.

Beautiful work though.

imiric

7 hours ago

Lovely, as all neal.fun experiments. <3

My favorite is probably https://neal.fun/infinite-craft/

This type of interactive learning experience reminds me of how fun it was to browse Encarta back in the day. It was full of interesting facts, presented in fun interactive ways. As much as I love that we have Wikipedia today, a static web page with text and limited multimedia is far less engaging and conducive to learning.

I think that Neal Agarwal and Bartosz Ciechanowski should be sponsored by the Wikimedia Foundation to create similar experiences on Wikipedia. That would do so much to facilitate learning for students of all ages.

M95D

10 hours ago

Incomplete. Where's the LEO, GEO, the counterweight?

rob74

9 hours ago

I think the idea behind this was less to showcase an actual space elevator and more to showcase what's going on at different altitudes. And above the Kármán line it would have become pretty boring, especially if you want to go up to GEO and beyond where the counterweight of a space elevator would be located - the Kármán line is at only 0.28% of the way to GEO. Using a logarithmic scale would have maybe helped, but not sure...

M95D

3 hours ago

There are other presentations by this guy are long. I don't consider the space and the things we put between LEO and GEO to be boring.

ta1243

9 hours ago

What's really interesting is that a space elevator goes to Geostationary orbit by necessity. Getting to 100km vertically doesn't save as much as you might think when it comes to getting into orbit.

To get into a very low earth orbit from an equatorial launch pad at sea level you need about 9.2km/s of Delta-V

To get there from a 100km tall tower, you need about 8km/s of delta-V - about 85%.

Think about how much scrolling there was to get to 100km.

To get to the ISS you'd need to scroll 4 times further. Starlink and Hubble are another 100km beyond that.

You start having radiation problems if you spend too much time above 600km.

Aside from Apollo, the highest a human has been is about 1400km - 14 times more scrolling than this page.

To get to GEO would require scrolling over 25 times further than even that.

matheusmoreira

6 hours ago

How much delta V would be needed to reach, say, a circular orbit from GEO altitude?

waxsum8

9 hours ago

Lovely, great transitions!

temperceve

5 hours ago

This is just lovely. I, for one, have bought Neal a coffee!

tonyhart7

10 hours ago

the website feels heavy, can we optimize this further?? (not a web dev)

randomtoast

10 hours ago

I just looked at it in the dev console in a chrome based browser and I think it is already pretty optimized. It runs very smooth on my device (Thinkpad T480).