I stand corrected that there are a lot of puzzles within physics that are unsolved.

Yet I still think there will be a finite number of them and if not yet more answers than questions as long as we keep trying the proliferation of new question will diminish whilst those answered will increase. Identifying the puzzles is a big step to solving them. Like many truisms, I think it will prove incorrect that the more we learn, the more we realize how much we don't yet know.

More specifically to the OP I'm not convinced solving the known unknowns is going to lead to FTL or other workarounds to the physics underpinning the time and resources issues for interstellar travel and I remain skeptical the set of unknown unknowns will reveal any. I would not be disappointed to be wrong - but possibly alarmed with it.

I will add that I think that for some of these puzzles resolving one may provide resolution to others - that the number of solutions needed will be less than the number of questions.

Edited June 20Jun 20 by Ken Fabian

Oh, you're such an optimist 🙂 .

I agree about our assumptions on 'sentient' beings, also didn't NASA find fungus growing on the outside of the ISS. There is also a reason why space probes are made in sterile environments to reduce the risk of contamination of planetary bodies.

It is possible we have already had visitors to Earth, this could explain why there are depictions found on different continents. I think on the ST voyager episode Tattoo (season 2) the inhabitants of the planet the crew visited said they took several generations to travel to Earth.

13 hours ago, TheVat said:

I was asking in regard to his saying "collimate" light from the sun. Am I mistaken that you need coherent light to succeed in collimating over any distance we're discussing? I may have misunderstood @DanMP in thinking that he was implying some way to make the sun emit coherent light. If I'm wrong on either point, happy to learn more about this. (Also thought the inverse square law meant sails weren't much use beyond Pluto, so were usually considered in context of solar system travel)

Collimation isn’t really necessary; you could be focusing the light near where the sail is. I think being monochromatic is the more important factor.

On 6/18/2026 at 11:05 AM, exchemist said:

On 6/18/2026 at 11:05 AM, exchemist said:

vanishingly unlikely

These are the key words, in this vast universe "vanishingly unlikely" becomes a certainty over large scale time and space. Unless it can be shown to be impossible it will happen eventually. The very fact that we can speculate ways it could be done that are not impossible points to this. Winning the lotto might be improbable but try to take away the winnings of the man who won with that excuse will no doubt be a problem.

I will admit that alien visitation is highly improbable, I have changed my approach to the subject having admitted that the data we currently have is does not meet the standards of science and the jet stream of bullshit currently emanating from the Trump regime cannot be trusted and so far is no better than lights in the sky being reported by Billy Joe Jim Bob after his friday night anal probe!

Edited June 20Jun 20 by Moontanman

1 hour ago, Moontanman said:

These are the key words, in this vast universe "vanishingly unlikely" becomes a certainty over large scale time and space. Unless it can be shown to be impossible it will happen eventually. The very fact that we can speculate ways it could be done that are not impossible points to this.

No it does not. Vanishingly unlikely in this case means our physics has to be wrong for it to occur. Our physics is not going to just become suddenly wrong if we wait long enough.

20 hours ago, MigL said:

Oh, you're such an optimist 🙂 .

Not really - societies and economies face some serious problems over the not entirely foreseeable future. If high levels of funding and support continue to flow to fundamental physics without discontinuities I expect more puzzles will get solved. I'm not entirely convinced that will be the case.

On 6/20/2026 at 1:11 PM, exchemist said:

No it does not. Vanishingly unlikely in this case means our physics has to be wrong for it to occur. Our physics is not going to just become suddenly wrong if we wait long enough.

How does physics have to be wrong for interstellar travel to occur? I see no reason why matter from one planetary system cannot travel to another planetary system. Can you elaborate on this?

1 hour ago, Moontanman said:

How does physics have to be wrong for interstellar travel to occur? I see no reason why matter from one planetary system cannot travel to another planetary system. Can you elaborate on this?

I guess he means FTL (e.g. stable traversable wormholes, etc) is disallowed, but current physics doesn't expressly forbid slower than light travel or finding ways to preserve living passengers on such long journeys. The question is more regarding what can feasibly be engineered. And there are collateral questions e.g. at relativistic speeds what level of radiation would a ship encounter and what amount of shielding needs mounted in the direction of travel.

Suppose we somehow discover a propulsion system that gets us to relativistic speeds in the range of 0.3 c. That seems a minimum for regular manned starflight given the times and distances involved, but suddenly attaining it doesn’t end our problems. Interstellar space isn’t empty, and when we accelerate to cruising speed at a substantial percentage of the speed of light, our encounter with interstellar gas becomes a nightmare. Indeed, this haze of gas between the stars acts as a flow of nucleonic radiation bombarding the starship as we push ever higher into relativistic realms....

https://www.centauri-dreams.org/2009/04/03/shielding-the-starship/

29 minutes ago, TheVat said:

Interstellar space isn’t empty, and when we accelerate to cruising speed at a substantial percentage of the speed of light, our encounter with interstellar gas becomes a nightmare. Indeed, this haze of gas between the stars acts as a flow of nucleonic radiation bombarding the starship as we push ever higher into relativistic realms....

It sure would be nice if you had gigantic Electromagnetic scoops that gather the interstellar gas/dust in your way, and use it as ejected mass, once energized by a matter-antimatter reactor, to generate forward thrust.
Something like a Bussard ramjet ...

2 hours ago, Moontanman said:

How does physics have to be wrong for interstellar travel to occur? I see no reason why matter from one planetary system cannot travel to another planetary system. Can you elaborate on this?

Firstly, I refer you to the opening post. Secondly, any journey would take so long that it would be pointless. No information could ever be sent back unless the senders were wi