4 ms·

Absolutely, but we'll need to develop some future technology that allows multiple days of constant acceleration. At 2G constant accel/decel, it'll take ~8.5 da

by claar 3y ago

Absolutely, but we'll need to develop some future technology that allows multiple days of constant acceleration. 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-a2235b28fce3 https://chat.openai.com/share/b93297e1-b089-46d1-8314-a2235b...). :)

riversflow 3y ago
Unless we develop force fields[1] I don’t understand how traveling at such relativistic speeds would work, at .023C a 1 gram micrometeor would have the same potential energy as 25 tons of dynamite (100B Joules) 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.
- spartanatreyu 3y ago
  > Ice shielding sounds good, but then we are back to the tyranny of the rocket equation. Not really, we don't have to lift up ice from Earth. We can just cook water out of clays in near earth asteroids.
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mrguyorama 3y ago
Assuming perfect efficiency in terms of adding energy to the velocity of an 80kg human payload, with zero other power usages, losses, etc, simply accellerating a human up to and back down from that speed takes about 1.6*10^16 joules, or about half of the daily output of the worlds nuclear reactors, or the ENTIRE volume of the Hindenburg as a bladder full of gasoline and a magic machine to extract 100% of the energy.
owenversteeg 3y ago
We can reach those speeds using the technology of today; Project Orion remains entirely possible and could be built in this decade, if we so chose. We are gods of our solar system, bound only by ourselves.
dgroshev 3y ago
This is incorrect, and I think this kind of low effort copy-paste of whatever ChatGPT came up with is actively harmful to the discussion. Honestly, I think this practice should be explicitly banned here. > 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 https://www.space.com/18709-uranus-distance.html [2]: https://en.wikipedia.org/wiki/Earth https://en.wikipedia.org/wiki/Earth [3]: https://en.wikipedia.org/wiki/Uranus https://en.wikipedia.org/wiki/Uranus
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- claar 3y ago
  I disagree. ChatGPT, at least v4 that I use, is simply fantastic for this type of back-of-the-napkin calculation. People lose out on its value with this type of pedanticism. 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!

by claar 3y ago

riversflow 3y ago

Unless we develop force fields[1] I don’t understand how traveling at such relativistic speeds would work, at .023C a 1 gram micrometeor would have the same potential energy as 25 tons of dynamite (100B Joules) 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.

spartanatreyu 3y ago
> Ice shielding sounds good, but then we are back to the tyranny of the rocket equation. Not really, we don't have to lift up ice from Earth. We can just cook water out of clays in near earth asteroids.
- deleted 3y ago
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mrguyorama 3y ago

Assuming perfect efficiency in terms of adding energy to the velocity of an 80kg human payload, with zero other power usages, losses, etc, simply accellerating a human up to and back down from that speed takes about 1.6*10^16 joules, or about half of the daily output of the worlds nuclear reactors, or the ENTIRE volume of the Hindenburg as a bladder full of gasoline and a magic machine to extract 100% of the energy.

owenversteeg 3y ago

We can reach those speeds using the technology of today; Project Orion remains entirely possible and could be built in this decade, if we so chose. We are gods of our solar system, bound only by ourselves.

dgroshev 3y ago

This is incorrect, and I think this kind of low effort copy-paste of whatever ChatGPT came up with is actively harmful to the discussion. Honestly, I think this practice should be explicitly banned here. > 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 https://www.space.com/18709-uranus-distance.html [2]: https://en.wikipedia.org/wiki/Earth https://en.wikipedia.org/wiki/Earth [3]: https://en.wikipedia.org/wiki/Uranus https://en.wikipedia.org/wiki/Uranus

deleted 3y ago
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claar 3y ago
I disagree. ChatGPT, at least v4 that I use, is simply fantastic for this type of back-of-the-napkin calculation. People lose out on its value with this type of pedanticism. 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!