Everytime I see these pictures I feel a little despaired... Are there people here who believe one day we could travel fast enough to go there ?
Humans? There are probably better destinations in the solar system that we’d go during the period between it becoming technically/economically feasible, and humans being replaced with robots.
At 2G constant accel/decel, it'll take ~8.5 days to get to Uranus, reaching a top speed of 2.3% of light speed (14.2 million m/s), and experiencing 17 seconds of time dilation (https://chat.openai.com/share/b93297e1-b089-46d1-8314-a2235b...). :)
Ice shielding sounds good, but then we are back to the tyranny of the rocket equation.
[1] which we don’t even have a path to, afaik. Straight scifi right now.
Not really, we don't have to lift up ice from Earth. We can just cook water out of clays in near earth asteroids.
We are gods of our solar system, bound only by ourselves.
> Distance: The average distance from Earth to Uranus is about 2.6 billion kilometers, but this can vary greatly depending on the planets' positions in their orbits.
Space.com (a relatively relatable source) thinks otherwise [1]:
> Because the solar system is in constant motion, the distance between Earth and Uranus changes daily. The closest the two get is 1.6 billion miles (2.6 billion kilometers). At their farthest, they are separated by 1.98 billion miles (3.2 billion km).
…which works out to ~2.9b km.
We can also calculate it ourselves. Earth is ~0.15b km from the Sun [2], Uranus is 2.7–3b km from the Sun on average [3]. Thus the distance varies between 2.65b km and 3.15b km, which means the average is (again) ~2.9b km.
Not 2.6b km as ChatGPT claimed.
Which changes the result to 8.9 days.
Which is not a huge difference, but would you know any better if ChatGPT said the distance is 5b km?
[1]: https://www.space.com/18709-uranus-distance.html
Let's take your question, "Would you know better if it said 5b km?". Nope, I wouldn't have a clue - or care!
ChatGPT informed me in SECONDS and 3-4 prompts that "At 2G constant accel/decel, it'll take ~8.5 days to get to Uranus, reaching a top speed of 2.3% of light speed (14.2 million m/s), and experiencing 17 seconds of time dilation."
Even if each of those numbers were off by a factor of two, it still gave me a greater intuition for the problem space than I had before.
I couldn't guess whether the flight time would be measured in days or years. With 4 prompts and 4 minutes invested, I had an answer within 11% (according to your sources, which I also didn't fact-check because it doesn't matter for this type of back-of-the-napkin work).
I didn't hide the fact of where this information came from - I cited my source. My hope was to share this new intuition of the problem space I'd received, so that HN viewers wouldn't have to invest even the small effort I did to enjoy these fun back-of-the-napkin numbers. The answer of <9 days was shocking to me!
Rather than banning intellectual curiosity and shunning use of our new amazing tools like ChatGPT/Claude/Bard/Mistral, I suggest we openly discuss and share our processes with each other. Who knows, maybe we'll learn something cool!
Here's its Python code it used to calculate travel days:
# Constants
acceleration = 2 * 9.81 # 2G in m/s^2
distance_to_uranus_km = 2.6e9 # Average distance to Uranus in kilometers
distance_to_uranus_m = distance_to_uranus_km * 1000 # Convert to meters
# Distance for half the journey
half_distance = distance_to_uranus_m / 2
# Time to reach halfway point (t = sqrt(2d/a))
# Using formula d = 1/2 * a * t^2, rearranged for t
time_to_halfway = (2 * half_distance / acceleration)**0.5
# Total time for the journey (double the halfway time)
total_travel_time = 2 * time_to_halfway
# Convert total time from seconds to days for easier interpretation
total_travel_time_days = total_travel_time / (24 * 3600)
total_travel_time_days
# Calculate top speed at halfway point (v = at)
top_speed = acceleration * time_to_halfway
# Convert top speed from m/s to km/h for easier interpretation
top_speed_kmh = top_speed * 3.6
top_speed_kmh
> Nope, I wouldn't have a clue - or care!
I find this just baffling right next to you talking about "greater intuition" or "intellectual curiosity". You don't care if your "intellectual curiosity" is feeding on complete misinformation?
You didn't do any "back-of-the-napkin math" (I did, but you, by your admission, don't care), you just took a plausible-looking factoid and run with it. It's equivalent to believing the first SEO spam listicle Google returned and calling it "intellectual curiosity" — worse, in fact, because at least there is a slight chance of an actual human checking those listicle "facts".
I believe the "process" you refer to is roughly:
- pay for GPT-4
- type a question in
- take the answer on faith
- post it elsewhere without doing any work to verify it
Is this correct? If so, I just don't think it's a good process. It also has no "back-of-the-napkin calculations" that you weirdly insist on, you didn't do a single addition in the entire "process".
How? Science isn't magic. If you want to get to places in the solar system on human time scales, you have to go FAST. Mars already is about 6 months away in the IDEAL circumstances. We don't have a good idea of how to go faster than we can now without literally blowing up nukes behind our ship, and hoping we can magically ride the waves reliably, and even that is not exactly revolutionary in terms of speed.
So now you're literally hoping for some scientific advancement that either bends space so that most things are "closer", allows humans to not die after a significant amount of down time but also makes humans not care about missing out on family and friends and making a brand new life anytime you want to go somewhere else, or a way to magically reach insane speeds. This is ignoring the fact that we don't even think massless propulsion is possible, let alone useful, so we would be stuck with using electricity to accelerate the lightest particles we can manage to as near light speed as physically possible.
People keep acting like science is some magic world and it's only a matter of time until science somehow does science fiction, but that's just as absurd as thinking it's only a matter of time until psychologists unlock the secret of telekinesis. It's fantasy. Reality has put very rough boundaries on everything, and while there is some wiggle room for new things to refine our understanding of the universe, any effects and forces we have yet missed would have to be so small or inconsequential as to be meaningless. If you think some future discovery would NOT be inconsequential, now you have to explain how it has hidden from us for all this time. Even "revolutions" in the field of physics that changed how we understand reality itself, like quantum anything, didn't totally change the math. Newton's equations are still mostly valid at human scales! The "wrong" model that caused the very Ultraviolet Catastrophe that lead to the discovery and building of quantum mechanics is still mostly correct for low frequency radiation!
This is a level of unwarranted confidence far exceeding my own, in my opinion :)
Uranus is 2.66 light-hours from the sun. At 0.01% light-speed, that's about 3 years. 3 years is a long time to travel, especially in the modern age, but not a long time to be alive, even for a human today. Is it possible we dramatically extend our lifespans or achieve technological immortality in the future? I certainly think so.
Can we reach 0.01c traveling between Earth and Uranus? Maybe not, because we have to accelerate half way and decelerate the second half. But I would feel much sillier saying that sub-decade interplanetary travel is absolutely impossible than saying that it's possible. Than saying we'll unlock new materials and techniques that make it possible eventually. I'm not even saying to expect them within a century. Think about millennia of uninterrupted technological advancement driven by superhuman AI - you're saying with certainty that it's not possible we'll figure out how to travel within our own solar system on human timespans after all that time? It'll be a boring future if we're already hitting the absolute limits of space travel and we've just started.
> Science isn't magic.
No, magic is just science we haven't figure out yet.
Death appears inevitable, but there's little difference between a century and a millennium as far as physics is concerned. I don't think it's far-fetched to assume we'll crack this one eventually.
> and making a brand new life anytime you want to go somewhere else
This has been the norm for travellers for most of human history. The modern two-day circumnavigation / perceptually-instant transatlantic broadband is nice, but not necessary. The solar system is a light-day in diameter (order of magnitude), so a round-trip by radio is faster than letters used to be.
There are other, better, designs for nuclear rockets beside the Orion drive. Some proof of concept devices have already been built. And if we could get our hands on sufficient quantities of anti-matter there are even better designs for anti-matter rockets. It’s an engineering problem not a problem of fundamental physics.