The Pioneer 10 plaque was designed by Carl Sagan's then-wife Linda Salzman Sagan.

Boosting this quality contribution up in the Hot Listing - declared quality by Boise_Lib.

Nothing in the laws of physics...except that you can't physically travel through time, yes.
Time is only this moment. There is no future or past to travel to.

Piezoelectric crystals do not work that way. Goodnight!

Then do it and shut up!

>> ^Fade:

Nothing in the laws of physics...except that you can't physically travel through time, yes.
Time is only this moment. There is no future or past to travel to.


Not according to some elements of General Relativity. Meaning, some would have it that the past, future and present have all already happened and just exist in a different dimension, call it the Z' axis. When Kurt Gödel wasn't destroying the foundations of logical positivism, he devised a time travel tabulation called the Gödel metric which allowed for curves in space time that one might be able to use some variant of what we all know as time travel. It is all theory, of course, and most of the theoretical methods for invoking time travel require a device of infinite size, or arranging matter in such a way as to destroy your time travel machine as it becomes a singularity...oops. Time is hardly understood really. We don't really know what it is when we talk about time, and by we, I mean everyone! Is time a particle, is it a matter or energy of sorts, is it conserved, how is it created if it is a substance of a sort? Is the apparent nature of moments of time in our minds indicative to "it's" nature, or just an arrangements of information in our mind...could some other mind have a very different idea of time? If so, how real is our notion of time, as it would appear that forward moving time would not be objectively real in that case. The debate on time travel, as far as I can see, isn't over...but mostly because we don't even know what time actually is! </rant of one of my favorite subjects!>

Time to go eat...

Edit (wanted to add that some hold that rats memorize events in reverse! What I mean is when they go through a maze, they remember coming out of the maze first, and going in last! AMAZINGLY DIFFERENT WORLD! As such, a rat has a much, much different idea of the "flow" of time as a forward flow of moments, his time jumps from now, to the then that was near to the then that was far and back to the "now" which will become another then that was near, then a then that was far...a jambalaya that we would have no idea how to make since of lineally, but it works so well for rats that they are one of natures most sucessfull pests.)

Huh, had no idea Ben Miller was quite so learned, especially after seeing the hilarious Armstrong and Miller chav pilot sketches.

Also, upvote just for the "If you're watching QI and you believe in astrology, you're banned" bit

I'm with Fermi.

Interestingly, the Fermi Paradox does a better job at disproving time travel than it does extraterrestrial civilization. Where you can argue that all the ETs just haven't developed space travel sufficient to the task or simply have not stumbled across us yet, the same cannot be said of time travelers. (i.e. If it was possible, we would have already met them, etc.)

If there are such thing as worm holes that can connect different points in time, then I only have one question:

Where are all these space worms?

>> ^soulmonarch:

... the same cannot be said of time travelers. (i.e. If it was possible, we would have already met them, etc.)


Assuming our species survives long enough to develop it, which is improbable, imho. If you believe that the development of time travel is inevitable (if it is possible), then the lack of visitors from the future may simply mean we are doomed, at least in this plane of the brane.

The Fermi Paradox doesn't disprove anything, nor was it meant to.

>> ^Fletch:

>> ^soulmonarch:
... the same cannot be said of time travelers. (i.e. If it was possible, we would have already met them, etc.)

Assuming our species survives long enough to develop it, which is improbable, imho. If you believe that the development of time travel is inevitable (if it is possible), then the lack of visitors from the future may simply mean we are doomed, at least in this plane of the brane.
The Fermi Paradox doesn't disprove anything, nor was it meant to.


I kind of like the sci-fi idea that we make a time machine in some distant future. The time travel event works, but also collapses to universe down to a singularity. Time time travel event works, however, and sends our time traveler back to the original singularity causing a massive disturbance, which causes the singularity to erupt. The end of time causing the start of time, to end all over again. All this completely consistent with the current understanding of general relativity.

He said "equivalence principle" when he meant "mediocrity principle". The equivalence principle has to do with the equivalence of gravitational mass and inertial mass. The mediocrity principle says that the Earth occupies a pretty average location in the universe (e.g. not the center of the universe).