We love science as much as the next geek, but sometimes it can be a real fun killer.
We accept that not everything in a fantasy series can exist in real life. For example -- dragons. Dragons are awesome, but we've all reluctantly accepted that none of us is ever going to stumble upon one and make it a pet.
But the gigantic wall of ice that protects the Seven Kingdoms from the perils of the north in Game of Thrones? That seems at least a little plausible. It's not as though ice structures have never been created by man before. Sadly, though, the reality is that it's not physically possible to bring a wall of ice like that into existence.
Let's look at the facts. The wall is meant to be 700 feet high and span a distance of 300 miles. Now, yes, in the books (and TV show) there is magic involved in the creation of this wall, but science is just magic for the mundane world. We can do a lot with science. So whay not a big, old wall of ice?
Well, according to engineer Mary Alibert from the Ice Drilling Program Office at Dartmouth College, "Even at very cold temperatures, large ice masses deform under their own weight. And over long time scales, ice flows, so it would not hold its original shape for thousands of years."
Basically, even if you measured twice, cut once, and got all your math right, the wall would shift and crack until the whole thing fell to rubble. The only chance we might hypothetically have is if we did the whole thing on a slope. According to physicist, Martin Truffer, "You would need a slope of at least 1 to 20 to stop significant deformation. So to keep it 700 feet high, I would estimate that wall to be about 40 times that in width." That's one thick wall. In fact, that's not so much a wall at all so much as it is an icy land mass.
Big Momma Nature might be able to make it happen, but that sort of thing takes thousands of years and, sadly, time travl is another one of those sci-fi things we haven't figured out yet.
Science, at least right now, has its limits. And even though, accoridng to Albert, "It would be a formidable barrier, since it is thick enough so that handheld projectiles or even artillery fire would not penetrate it," we're just not there yet. But we'll hold out hope that, someday, the impossible will become possible. After all, any sufficiently advanced technology is indistinguishable from magic, right?