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[Max™]

Find me a loop of cosmic string and an amicable Xeelee.

[Reelya]

Also, I think my favorite argument against the likelihood of time travel machines is that "if it hasn't existed yet, then it won't exist later". If someone had made one, they would have traveled back in time.

Stephen Hawking apparently has an interesting take on that in a post-humously published book that was just released.

Say you need a wormhole to travel back in time through, but you have to make the wormhole first, then you can travel back to when the wormhole was created. Or any sort of similar situation where you can make some sort of time-tunnel then send stuff through it. If that was the case, the no civilization could ever travel back in time to before they made the receiving-end of the tunnel.

[Max™]

That's a fairly normal result of assumptions that relativity broadly holds but wormholes are possible. If you could make a pair of stable holes and move them around you could run one end off on a rocket to accumulate time dilation and bring it back in a thousand years or something, then hop back and forth assuming it didn't all kersplode.

[hector13]

Everyone knows the only way to travel back in time is to make the planet spin backwards, a la Superman.

[ChairmanPoo]

I thunk the idea was that he was going so fast rhat time ran backwards. Still handwve physics but less silly than Earth spin

[Loud Whispers]

I thunk the idea was that he was going so fast rhat time ran backwards. Still handwve physics but less silly than Earth spin

The best explanation I heard was that the Earth was spinning backwards to indicate the reversal of time, not that spinning the Earth backwards made time reverse

[Starver]

I think my favorite argument against the likelihood of time travel machines is the physical impossibility of backward time travel.

It's not proven to be physically impossible, and the possibility even comes directly out of (current understandings of) space-time equations. As was said in the intervening interval between our two posts, most theories involve preparing your time-machine(/gateway) so that until it exists you can't have had someone coming from the future who will have eventually had the opportunity to make their future travel into the past that is your now.

Which is not to say that there aren't already such twists, waiting (fated!) to be used - and therefore have been used, already to exit in your past. Maybe you having done so.

And the theories of how they then work with paradoxen tend (in the absence of experimental evidence) to support the self-sustaining causality loop (a billiard ball heading towards a time-travel billiard-pocket that would eject the spheroid out to interfere with its past self and cause it to miss (which would mean it did not get opportunity to deflect itself) is an unsupportable energy-balance, whereas the ball that only goes into the pocket because of a collision by its future self (an event that must already have happened) is fine.

Self-bootstrapping events are fine (see also All You Zombies) although not in isolation (a ball that appears from the future to become the ball that goes back into the past) has various problems with personal stability given the non-zero chance of (among other things) proton decay that must occur over each iteration, making for transfinite changes each time round, which is every time around.


Which is not to say that it might not be different in reality (if we ever identify such a thing as 'reality'), but if anybody's come back from the future to give us the proof that irrepairably altering your own timeline is possible but results in you fading away (while performing rock music) they may have only been taken seriously by a scriptwriter, not any scientist (not otherwise invested in the project).

[Dunamisdeos]

Here's some news nuggs for you folks.

CIA concludes Saudi crown prince ordered Jamal Khashoggi's death, sources say

Additionally

"The murder of Jamal Khashoggi was an atrocity. It was also an affront to a free and independent press and the United States is determined to hold all of those accountable who are responsible for that murder,"

I guess it's time to blow some shit up in the Middle East again. It's the weekend in the US after all, gotta fall back on the classic pastimes.

[Rolan7]

Well poop, I agree with Pence about something.
I wonder what Trump's position is, considering how much he was defending the Saudis earlier.  Technically he was avoiding a rush to judgement, which is fine, but... when else has Trump ever avoided rushing to judgement?

Also, I think my favorite argument against the likelihood of time travel machines is that "if it hasn't existed yet, then it won't exist later". If someone had made one, they would have traveled back in time.

Stephen Hawking apparently has an interesting take on that in a post-humously published book that was just released.

Say you need a wormhole to travel back in time through, but you have to make the wormhole first, then you can travel back to when the wormhole was created. Or any sort of similar situation where you can make some sort of time-tunnel then send stuff through it. If that was the case, the no civilization could ever travel back in time to before they made the receiving-end of the tunnel.

The movie Primer had that same limitation.  Maybe the only time travel story I'd call hard sci-fi...  Really good, though I'm still not sure what actually happened.

[Dunamisdeos]

Looking at his previous quotes.... it's like the only time he's shown restraint at anything, ever. He said they were strong allies in economic and job-creating terms which is accurate, then followed up with a desire to wait until we found out what happened.

I'll take it.

[Trekkin]

Looking at his previous quotes.... it's like the only time he's shown restraint at anything, ever. He said they were strong allies in economic and job-creating terms which is accurate, then followed up with a desire to wait until we found out what happened.

I'll take it.

What's left to find out, though?

[JoshuaFH]

He's gonna take out the cardboard highschool presentation showing how much money Saudi Arabia gives us (read: him) and call it a day. 

[Dunamisdeos]

Looking at his previous quotes.... it's like the only time he's shown restraint at anything, ever. He said they were strong allies in economic and job-creating terms which is accurate, then followed up with a desire to wait until we found out what happened.

I'll take it.

What's left to find out, though?

That was from when the story first broke, IIRC.

He's gonna take out the cardboard highschool presentation showing how much money Saudi Arabia gives us (read: him) and call it a day. 

I mean, probably.

[sluissa]

Looking at his previous quotes.... it's like the only time he's shown restraint at anything, ever. He said they were strong allies in economic and job-creating terms which is accurate, then followed up with a desire to wait until we found out what happened.

I'll take it.

He'll avoid rushing judgement on just about anyone he likely financial ties with. It's basically a pattern with him.

Anyone else, where money isn't involved, and they're not more powerful in a personal sense*? Screw em.


*As in, say, Putin, while you might say the US president is more powerful than the Russian president just based on strategic power. Putin is about to exercise that power more freely than Trump is. Same with all the other dictators, monarchs, and otherwise notable "strong men" leaders Trump seems to respect for basically no other reason.

[Dunamisdeos]

Looking at his previous quotes.... it's like the only time he's shown restraint at anything, ever. He said they were strong allies in economic and job-creating terms which is accurate, then followed up with a desire to wait until we found out what happened.

I'll take it.

He'll avoid rushing judgement on just about anyone he likely financial ties with. It's basically a pattern with him.

That's probably true, yeah.