According to Kent Harrison, a noted scholar in mathematical physics, despite considerable progress in the twentieth century, our understanding of space and time still seems rudimentary. Numerous tantalizing scriptures refer to space and time: "All is as one day with God, and time only is measured unto men" (Alma 40:8); . . . "Kolob was after the manner of the Lord, according to its times and seasons in the revolutions thereof; that one revolution was a day unto the Lord, after his manner of reckoning, it being one thousand years according to the time appointed unto that whereon thou standest" (Abraham 3:4); . . . "One day is with the Lord as a thousand years, and a thousand years as one day" (2 Peter 3:8).
It is interesting to consider these statements in the context of Albert Einstein's relativistic view of time and space. As understood from his theory of special relativity set forth in 1905, measurements of time duration and space extent may range from one frame of reference to another, depending on the exact experiment performed and on the frames' relative motion. In addition, one's speed through space is limited to speeds lower than the speed of light, rapid for Earth life but incredibly slow if one wants to travel in space. Thus, special relativity seems to be inconsistent with the existence of prayer and of travel for celestial beings, both of which seem to be extremely rapid.
Many people have asked me what special relativity has to say about theology; I usually answer that I don't know. The apparent numerical correspondence between God's time and man's time indicated by Abraham 3:4 (one day for the Lord equals a thousand years for man) is sometimes taken as a definite ratio of time scales, perhaps arising in special relativity. However, according to relativity, that ratio would require the Lord and man to be traveling at nearly the speed of light--for along period of time--relative to each other. This sort of thing seems preposterous.
A better interpretation is suggested by 2 Peter 3:8, which speaks of the ratio of a thousand years to a day operation in both ways. I regard that simply as indicating that time, as perceived or controlled by God, is very different from our perception. This suggests that it would be premature to force the meaning of these scriptures beyond that point and avoids the temptation to try to work out some sort of definite numerical correspondence of the two scales (as has often been tried by LDS people). Relativity may still play a role, but we do not know as yet what that role might be. . . .
Although space and time travel would appear to be highly difficult to achieve, they cannot be entirely ruled out. However, an object or individual making such transport would likely be required to be made of exotic matter of a type not available to us on Earth. . . . Nevertheless, such space travel or time communication appears possible, even required, from spiritual experiences as stated in scripture and elsewhere. How does God know the end from the beginning? (see Abraham 2:8). How did he know, thousands of years in advance, that Joseph Smith would lose the 116 pages of manuscript and that an alternate set of records would be needed? (see Words of Mormon 1:6-7). Again, how was it possible for Moroni to travel through space, to appear, in a boy's bedroom, standing in the air, having control over gravity as well as space and time? (see Joseph Smith--History 1:30). In what sense is God above time? . . .
Alma 40:8--"all is as one day with God, and time only is measure unto men"--makes the dichotomy clear, although it does not help us understand God's time. Presumably, in God's universe cause precedes effect and there is eternal progression, which would suggest some sort of time order--but beyond that we cannot go. We can only ask whether God's understanding applies just to our universe or to the (possibly) more extensive space and time in which he dwells. [B. Kent Harrison, "Truth, the Sum of Existence, " in of Heaven and Earth: Reconciling Scientific Thought with LDS Theology, pp. 163-166]