What do you think is truly impossible in the universe?

[Maximum7]

What science, technology, astronomical bodies, energy sources or engineering projects truly cannot exist in the universe?

[firestar464]

violation of thermodynamics

[wjfox]

Perpetual motion machines.

[Bird]

Faster-than-light travel.

[Tadasuke]

Going back in time probably.

Though it's possible to slow down time, you would still move forward in time, I don't think it's really feasible to go backwards. But there will be virtual simulations.

[Vakanai]

I hope I am wrong, I truly, truly do.

1. Warp/Alcubierre Drive
2. Traversable Worm Holes
Worried the amount of exotic energy needed will put an end to such dreams. Which means we will never colonize our galaxy, unless we spend tens of hundreds or millions of years to do so. And billions of years to colonize other galaxies to any great extent.
3. Because of the first two, Time Travel (pretty much this has to exist in some form if the other two prove possible)

[wjfox]

1. Warp/Alcubierre Drive

If we can harvest antimatter, it would greatly improve the available energy. We're talking billions of times more than chemical-based rockets. I believe we'll achieve this, and it's scientifically possible. But likely centuries away.

[firestar464]

It is possible

https://phys.org/news/2024-05-subluminal-warp.html

[Vakanai]

1. Warp/Alcubierre Drive

If we can harvest antimatter, it would greatly improve the available energy. We're talking billions of times more than chemical-based rockets. I believe we'll achieve this, and it's scientifically possible. But likely centuries away.

That's a big if. And it's not centuries away, not when we're close to an age of AGI - either it will happen this century or we discover it can't happen at all, least not to the extent for practical applications.

It is possible

https://phys.org/news/2024-05-subluminal-warp.html

That's...not what that article says. It says it "may" be possible, not that it is possible. "According to current theory, it would not be possible to construct warp drives in the real world. But current theories may have to be amended if the work by the team on this new effort pans out." So the current theory needs to be wrong and the new theory right. Which might be the case. It looks like more research and testing needs to be done.

Edit: Both my responses probably sounded more antagonistic than I meant them. Sorry, blunt force brain in charge right now. I'd love to be wrong - like most people the thought of getting around the hard light speed limit so we can actually become a galaxy-wide or galaxies-wide ranging species is something I want to become true for us.