this post was submitted on 27 Jul 2023
168 points (83.1% liked)

UFOs

2719 readers
3 users here now

This community is for discussion surrounding UFOs and Extraterrestrials.

Rules

  1. Be your own moderator
    • Think before you post or comment, and use your common sense about what is acceptable. This is a community space and should ultimately be community-driven. Be the community you want to see here.
    • If you are here because you want to make fun of or grandstand over all of the silly people who believe that UFO/UAPs may exist, you are not welcome. Just block the community and go about your day.
  2. Be Civil
    • No trolling or being disruptive.
    • No insults or personal attacks.
    • No accusations that other users are shills/agents. If you have some kind of evidence of this, please report instead.
    • No hate speech or abusive speech based on race, religion, sex/gender, or sexual orientation.
    • No harassment, threats, or advocating violence.
    • No witch hunts or doxxing.
    • No summarily dismissive comments (e.g. "Swamp gas.").
  3. Posts must be related to UFO/UAPs
  4. Avoid duplicate posts
  5. Link posts should contain the linked content and a submission statement
    • Submission statements should contain a summary of the content, why it is relevant to UFOs, and optionally personal perspectives.
    • For short-form content, such as tweets, include the entire text.

founded 2 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
[โ€“] [email protected] 1 points 1 year ago (1 children)

Ah, I misread a wiki page. Not infinite, since we aren't traveling lightspeed, but approaching infinite as we approach lightspeed? Which is to say, not infinite but dang thats a lot of energy?

Again, I'm not great at understanding this stuff, so thanks for being patient

[โ€“] [email protected] 1 points 1 year ago

Sure, I don't mind explaining. No, we would not need near-infinite energy. We are quite capable of accelerating at 10 Gs in space right now, but eventually you will run out of fuel. So, let's say you add more fuel, well now you have more mass to accelerate so it costs more fuel per second. This becomes a balancing act which we can not overcome for long, and it's the reason space shuttles are so complicated and have multiple stages which break away to reduce mass.

This is primarily an issue because we use quite simple propulsion techniques, which rely on Newton's third law -- that forcing mass out from behind a ship will propel it in the opposite direction. It may be possible to accelerate using an Electro-Magnetic field, which would not involve burning fuel but instead some kind of depleting battery storage, or perhaps a nuclear reactor. In this case, accelerating at 10 Gs is simply a matter of matching the energy requirements to the mass of the ship, and for some perspective on the energy capabilities of nuclear fission, the Little Boy bomb reacted less than a gram of nuclear material to create the explosion in Hiroshima.

The uranium in the Hiroshima bomb was about 80 percent uranium 235. One metric ton of natural uranium typically contains only 7 kilograms of uranium 235. Of the 64 kilograms of uranium in the bomb, less than one kilogram underwent fission, and the entire energy of the explosion came from just over half a gram of matter that was converted to energy. That is about the weight of a butterfly.

So, obviously we aren't capable of converting that energy into a useful method of propulsion yet, but have some heart, because the pieces are all there -- we just need to put them together.