High Time

In other, less magical worlds, current theories of physics include the concept that gravity slows down time. If you have a sufficiently massive object and can get a large enough difference in altitude, you can even compare two (very accurate) clocks and find that the higher of the two has been running faster, whereas the lower has been dragged into slower motion by the greater forces of gravity.

The planet of Neopia, perhaps because it is intrinsically magical, appears to take this phenomenon even further. In examining the assorted worlds or nations of Neopia, I realized that there seemed to be a rough but noticeable correspondence between altitude and technological development -- or in some cases between altitude and historical era. In fact, in some areas, it appears that it may be possible to travel in time by traveling in altitude -- going uphill or into the air, or going downhill or underground.

The worlds with space-age technology are, naturally enough, in orbit; the worlds that are supposed to represent previous eras of Neopian history (Meridell, Brightvale, Tyrannia) are all low in altitude. Tyrannia has even been referred to as being underground, although that seems a little unlikely given its apparently normal access to sky and sun. With these in mind as reference points, I decided to examine the rest of Neopia's worlds to see how well the correspondence holds.

Let's take it from the top.

Orbit

The highest altitude worlds in Neopia are the moon Kreludor and the Virtupets Space Station, both in orbit around the planet itself. Necessarily, both have extremely advanced technology; there would be no way to survive in the vacuum of space without advanced protective measures. In fact, because of their association with Dr. Frank Sloth, these worlds have electronics and engines where the vast majority of Neopia relies on magic. This may be less a result of time proceeding faster with altitude than of association with off-planet technology; Dr. Sloth is believed to have been on Neopia longer than most if not all species of Neopets, but arrived from elsewhere, and he brought the Grundos from their own home planet to serve him. On the other hand, it is unclear when and where Sloth developed the technology he uses, and he may well have invented a great deal of it while concealed in orbit.

The Alien Aishas are also quite technologically advanced, able to engage in long-distance space travel and exploration as well as to mimic Faerie magical technology, although their culinary tastes are... well... alien. Despite their resemblance to the Neopian species of Aishas, however, they don't seem to be primarily based within Neopia's gravity well, so they probably don't really count as evidence.

Floating

There are also nations in Neopia that float within the atmosphere. While the fact is not widely recognized, Faerieland, the thriving city in the clouds, is actually one of Neopia's primary technological centers. A full exploration of the matter would provide substance for another article, but in brief: technology is, essentially, applied science; magic is part of Neopian nature and thus falls under Neopian science. Faerieland therefore contains a high concentration of magical technology, which it distributes to the rest of Neopia through games, in exchange for quest services, and through outright sale.

The technological status of the Darigan Citadel appears to be moderately elevated with respect to Meridell, over which it floats. The correspondence between altitude and technology is somewhat complicated here by the fact that the Citadel appears to have been uprooted (in itself an impressive feat of magical technology) and moved from some unknown location to hover over Meridell instead. The original altitude is unclear, and there is evidence that the height at which it floats is adjustable. In any case, Darigan seems to have resorted to developing magical spells and engines of war to compensate for the curse produced by the loss of the Golden Orb. Darigan also seems to have thrown a fair amount of energy into developing clockwork, although most of the applications are toys.

High Ground

Terror Mountain! Atop and inside this lofty peak, we have two faeries and a variety of interesting games and shops, including one where the available items are disguised from potential buyers until after purchase, presumably by either clever packaging or an effective illusion. There isn't anything that particularly stands out to me about Terror Mountain's society/technology (except that they are obviously well adapted to the cold); judging from clothing, I would guess that they have a similar culture to Neopia Central right from the peak down to Happy Valley, except not quite as busy and much colder. This doesn't exactly support my theory. The Ice Caves lead to the long-frozen Bori and used to lead to Tyrannia, but underground routes through Terror Mountain are still rather higher up than much of Neopia.

Unspecified

There are several Neopian regions where the altitude can't easily be gauged from their names. Neopia Central, where every human resident starts out, is one; others are the Lost Desert, Haunted Woods, Mystery Island, Krawk Island, and the mini-worlds of Kiko Lake and Roo Island.

Neopia Central and the Haunted Woods seem relatively modern, as do the mini-worlds, although the Haunted Woods by nature seem to have ties to the past, the gone (or not quite gone), and the deteriorated. Still, the carnival games at the Deserted Fairground appear to be functioning as intended (as distinct, it should be noted, from functioning fairly) and several have rather advanced construction. Some of this may be influenced by external interactions, however; the exploding clockwork Chia clowns in Haunted Carnival were apparently built by Dr. Sloth.

Krawk Island appears to be generally somewhat lower-lying than Mystery Island. These two may be "reversed" from the overall theory, although the point is open to some argument. Mystery Island has significantly more ties to tradition and a more relaxed lifestyle, and there are still parts of the population that remain very isolated. While perhaps appearing less "modern" in some respects, however, this may easily be considered more advanced than the piracy prevalent on Krawk Island and the neighboring Scurvy Island.

The Lost Desert's altitude is uncertain; it seems relatively flat, but whether it's at or above or below sea level is unclear. The Lost Desert is very deeply rooted in tradition and very advanced at the same time; it's a matter of building on a foundation, I think, more than of either retaining a comfortable status quo or getting literally stuck in the past. The level of communication and interaction with the rest of Neopia is also unclear; there is definitely travel back and forth and a certain amount of tourism, but according to the recent Lost Desert plot it still isn't very common knowledge across Neopia.

Low Ground

Meridell, Brightvale, and Tyrannia all seem to be "low ground." Meridell and Brightvale have names suggesting that they reside in valleys -- low ground at least with respect to the surroundings. Tyrannia was originally discovered (at least by non-residents) through a deep crevice in the Ice Caves. Evidently, while not precisely underground, it lies low enough and in sufficiently prohibitive geography that it was actually overlooked for several centuries, preserved in its former condition -- or else that crevice actually opened onto the other side of time. By now, it seems that these relics of both "medieval" and "prehistoric" Neopia are in regular contact with the rest of the planet, though they retain much of the previous culture. Tyrannia, in particular, somehow seems to have acquired the largest concert venue in Neopia -- the only one that's widely publicized, actually, although there must be minor local ones where such bands as Gruundo and The Hikalakas get their start.

Conclusion

The correspondence between altitude and time, technology, or culture is something of a rough one. Highly advanced, forward-looking, or even futuristic worlds do tend to be high in altitude. Worlds from previous periods of history, with a strong sense of history, or with a nostalgic, traditional, or back-to-nature air do often seem to be around sea level or below -- but it isn't necessarily linear. In many -- perhaps most -- cases, the differences in apparent era can be attributed to factors such as necessity (one can't survive in space without some technological assistance, whether electronic or magical depending on whether you've been in touch with Sloth or the faeries), and there are in other cases considerable effects attributable to the travel, trade, and other interactions between worlds.

In short, it is true that "futuristic" worlds and those with exceptional magical technology are high in altitude and that worlds "stuck in the past" or reflecting previous periods of Neopian history seem to be low. In terms of general culture, however, it seems likely that other factors -- communication vs. isolation, climate, and so forth -- have an effect strong enough to obscure the magicophysical effect of altitude on time, which may also require larger differences in altitude to be observed reliably. There may also be a psychological tendency to place centers of "higher" learning or accomplishment in a literally higher location (e.g. Techo Mountain and the training schools, the Tyrannian Concert Hall on a plateau, Lost Desert pyramids), though this is not invariable.