To Help You You Understand Why Interstellar Travel Is Probably Never Going To Happen......

[ToraToraTora]

 

[mibn2cweus]

Theoretically, at a constant acceleration of 1g one could arrive at the Andromeda Galaxy within 30 years; or just fifteen years for a fly by.

[ToraToraTora]

That would exceed c mibn

[Arksided]

I'm open to all possibilities and don't feel constraint to the science that we have now known to be true-ish.

"The only Universal constant is change"

Albert Einstein

[naomi24]

Arksided, I like that quote.

[andy-hughes]

So do I, since Mr Einstein is happy to approach the future with the same open mind as me.

Maybe all the arguers will accept an unknown future from someone more qualified to comment than any of them. 

[mibn2cweus]

Question Author: That would exceed c mibn

Not quite. Time passes more slowly for someone as they approach c compared to those they left behind. The travelers 30 year journey to the Andromeda Galaxy would have taken over 2.5 million years from an Earth bound observer's point of view.

It's all relative.

[ClareTG0ld]

I haven't checked the calculations but mibn's suggestion sounds about right.

But on the subject of change, it really is worth stressing that Einstein himself understood the importance of not just finding the new, but building on the old. His theories didn't replace those of Newton, so much as improved on them. Indeed, we can know this by tracking Einstein's own work: it wasn't until he was confident that he could recover Newtonian gravity from his new ideas that he could claim to have a robust new idea.

That's a part of the story that is easily lost, but it's why, in the context of faster-than-light travel, I've been so assertive that it's at the very least extremely unlikely to be wholly wrong. There may be clever ways around it, be it finding "short-cuts", but the central idea is at this point solid after well over a century of stringent testing. Any "change", therefore, will at this point merely add to, rather than replace, Relativity.

[Peter Pedant]

"Another one who thinks science has advanced so far that it has reached its boundaries. " 

physics is now just computing to the tenth decimal place

That would be Lord Kelvin (William Thomson), who made this statement in the late 19th century. He later had to retract it due to the groundbreaking discoveries of radioactivity and the electron. - 1897 I think.

 

[andy-hughes]

Clare - // That's a part of the story that is easily lost, but it's why, in the context of faster-than-light travel, I've been so assertive that it's at the very least extremely unlikely to be wholly wrong. //

But that doesn't mean that it's not, it just means that's what we think today, because we have no idea what the future may hold, and what advances may destroy many scientific beliefs held for hundreds of years.

We don't know the future, and the balance of probability is just that - not the future told now.

[Peter Pedant]

I have that as heraclitus

The Greek philosopher Heraclitus is credited with the idea that the only constant in life is change. Only fragments of his writings remain, one in which he says: Everything changes and nothing remains still; and you cannot step twice into the same stream.29 Nov 2021

remember that Pythagoras was a " everything is measure" - pan esti metron.

 

[Peter Pedant]

Indeed, we can know this by tracking Einstein's own work: 

yeah but no but - he was wrong on the cosmological constant, and discouraged the Belgian Priest ( " Your maths is farry boodifoll, but the idea is terrible) ( Georges Lemaitre) who was an early big-banger

and followed it up with 'God does not play dice' - showing he (E) thought the universe was deterministic. 

PS I passed physics O level 1966

[ClareTG0ld]

There's no such thing as 100% certainty in science. But there's stuff that's pretty close to it. It's a mistake to confuse something being not literally 100% certain with , in effect, equivalent to a coin toss.

At this point, the weight of evidence in favour of the assertion that the speed of light is an absolute limit is broadly similar to the weight of evidence in favour of the assertion that the Sun will rise tomorrow.

[tomus42]

For the sake of argument, let's assume that all the current laws of physics as we know them will at some point be rethought to the point where we suddenly find we can travel 1000s of light years in a short time.

A) We can't even live reasonably together on this place that we know is perfect for us, without destroying it and killing each other. What chance have we got anywhere else?

B) it's not going to happen, so don't worry about it.

[ClareTG0ld]

On the specific topic of interstellar travel, though, as mibn says you can in principle take a journey to Andromeda that, from your perspective, takes only a matter of years. There are no theoretical barriers to that. There are, however, plenty of practical ones -- not least of which is that the journey will always take at least a couple of million years from anybody else's perspective, making it not exactly useful for any kind of communication etc. Also, there would be the fuel problem -- the fuel required to sustain a 1g acceleration, and then to reverse it, is prohibitively high, and even if you can find a more efficient way of converting a certain fuel to energy, that doesn't change how much energy cost there will be. 

On the other hand, these are engineering problems, which can -- at least at more modest scales, and assuming you could get the money -- be solved in future. 

[mibn2cweus]

Never say, "never".

Opps, just said it . . . twice.

[naomi24]

Haaa!  Sperlatt!

[mibn2cweus]

Can't say, "I didn't see that coming."

Oops...