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Has time travel ever been discussed before in terms of Judaism? According to Judaism would (should) it be possible to travel through time?

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@WAF hmm. What do you mean by that question? – yydl Aug 3 '11 at 16:42
Would your question be intelligible to a "traveler through time" or would the answer to such a person be "obviously yes" or "obviously no"? – WAF Aug 3 '11 at 16:53
...but the real question is what happens when you time travel during sefirah? Do you celebrate Shavuot on a different day than everyone else? – Charles Koppelman Jul 18 '12 at 15:39
@CharlesKoppelman judaism.stackexchange.com/q/322 – msh210 Jul 18 '12 at 19:03
We are always traveling through time. – Daniel Apr 24 '13 at 4:49

In Menachot 29B, the following story is told (English taken from page 112 of here):

Rab Judah said in the name of Rab, When Moses ascended on high he found the Holy One, blessed be He, engaged in affixing coronets to the letters. Said Moses, ‘Lord of the Universe, Who stays Thy hand?’ He answered, ‘There will arise a man, at the end of many generations, Akiba b. Joseph by name, who will expound upon each tittle heaps and heaps of laws’.

‘Lord of the Universe’, said Moses; ‘permit me to see him’. He replied, ‘Turn thee round’. Moses went and sat down behind eight rows [and listened to the discourses upon the law]. Not being able to follow their arguments he was ill at ease, but when they came to a certain subject and the disciples said to the master ‘Whence do you know it?’ and the latter replied ‘It is a law given unto Moses at Sinai’ he was comforted.

Thereupon he returned to the Holy One, blessed be He, and said, ‘Lord of the Universe, Thou hast such a man and Thou givest the Torah by me!’ He replied, ‘Be silent, for such is My decree’. Then said Moses, ‘Lord of the Universe, Thou hast shown me his Torah, show me his reward’. ‘Turn thee round’, said He; and Moses turned round and saw them weighing out his flesh at the market-stalls. ‘Lord of the Universe’, cried Moses, ‘such Torah, and such a reward!’ He replied, ‘Be silent, for such is My decree’.

It could very easily be argued that the whole thing was a vision, but it does say that Moshe went and sat behind the 8th row and that he returned to G-d afterwards.

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Does that refer to the tannaitic Akiba b. Joseph? – Peter Olson Jun 25 '11 at 1:47
@PeterOfTheCorn: yes – Menachem Jun 26 '11 at 1:44

Shivchei HaBesht records an episode where the Baal Shem Tov wrote a letter to his brother-in-law R' Gershon of Kitov, telling him how he had been taken to task by the Heavenly Court for excommunicating a Torah scholar without sufficient cause. R' Gershon wrote back to say that this indeed had happened, but only after the date of the Baal Shem Tov's letter - in other words, he "time-traveled" and saw the incident before it occurred.

The Tzemach Tzedek of Lubavitch points out (Derech Mitzvosecha, Mitzvas Haamanas Elokus) that the Divine flow of energy to the world - both its spatial and temporal aspects - gets divided progressively finer during its "evolution" through the spiritual "worlds" leading down to our own. There is a level, he says, at which one moment contains ten to fifteen years' worth of events in our realm; it is this level, he says, that the Baal Shem Tov reached and thereby foresaw what was to happen.

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Somewhat unconventional, but:

While commenting on a different point in the gemara (Chulin 91b), R' Yitzchok questions how Yaakov was "vayifga bamakom"- he chanced upon the place (Beis El/Yerushalayim) if the pasuk implied that he already reached Charan- vayelech Charana. R' Yitzchok answers that the land shrunk for him. Assuming space and time are interwoven, Yaakov would have traveled ahead in time as well.

The gemara continues the above by questioning why the Torah wrote "ki va hashemesh"- Yaakov lodged because the sun had set- implying that it set prior to its normal time. If not for the gemara's answer (that Hashem wanted the tzadik to lodge by Him and so made the sun set early so that Yaakov would be unable to depart), it's possible to say that for Yaakov, the sun set early because time bent for him along with the land.

Note: I have no clue if the math works out.

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Time-travel into the past, according to Stephen Hawking's latest Scientific-Theory, is inherently a paradox. Paradoxes cannot exist in nature and as such, reverse-time-travel is physically impossible.

According to the Rambam, Hashem only does possilbe-miracles, where Hashem uses His direct-control of the physical world to perform natural-wonders. The Rambam addresses the classic question 'could Hashem create a square-triangle' (can God do anything impossible)? The Rambam's revelation is that Hashem can't make a square-triangle (he can't do something physically-impossible), but that's not a limit of Hashem's power, since He made the restrictions of our physical world. He said something along the lines of 'let the goyim have impossible-miricles, we'll have possible ones' (their miracles can't happen, ours can and do).

Accordingly, the Rambam would hold that reverse-time-travel, as a paradox of nature, would not be a miracle Hashem could perform.

Hawking's theory, that traveling to the past is a paradox and impossible, is also supported by a halacha from Talmud Bruchos, that it's assur to pray to change the past.

If you hear that there is a fire in your town, you shouldn't pray that it wasn't your house, it's too late if your house is on fire, and Hashem isn't going to go back and change it. instead you can pray that it won't spread to your house if it wasn't your house, or that they will be able to put it out quickly.

Also along those lines, expecting parents shouldn't pray that their baby be a certain sex after the first 40 days of pregnancy, since after 40 days the fetus already formed its sex-organs and Hashem's not going to go back and change it. (Berachot 60A)

Another quantum-halacha is once something observed, it can't be changed. (once it's seen it can't be un-seen)

I don't know where this halacha is from, but I was taught that you shouldn't count your money because, if you know how much money you have (you've observed it) then Hashem can't slip you more without your knowing (Hashem can't change it once you've observed it).

This would mean that since the past was observed by the people living in it, Hashem cannot send you back to change it.

Scientifically, observations effecting reality relate to Schrödinger's cat & Relational quantum mechanics.

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I think the last concept is called "Blessing is only found in the hidden", I'm not sure where it's written. – chaimp Nov 24 '11 at 8:25
-1 Hawking's theories, as brilliant as they are, have no bearing on halacha. The concept that one ought not pray about past events has no connection to the feasibility of time travel. I don't have enough halachic source material on this for an answer, except to say that time is, in and of itself, a creation. If G-d wants to allow people to travel through time, nothing that Hawking or any other human being observes in the physical world can stop G-d from allowing it. – user1095 Jan 9 '12 at 17:23
@ will, One shouldn't pray to change past events because Hashem won't change the past. I think that's very connected to time-travel. -- While I agree that time is a creation, that doesn't mean that Hashem can do 'whatever he wants with it', at least according to the Rambam. A square cannot be a triangle, it's illogical, and Hashem can't make one in our physical world due to the restrictions that Hashem set. So if reverse-time-travel is also illogical, then according to the Rambam it would be impossible for Hashem to perform. – zaq Jan 9 '12 at 20:19
This doesn't address the first part of the question - has it been discussed? RaMBa"M was not discussing time travel (even though you are applying his comments that way). – Seth J Jul 18 '12 at 18:48

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