(Old Norse bifrǫst, literally the "tremulous way", from bifask "to tremble" and rǫst "a distance") in Norse mythology is the bridge leading from Midgard, the realm of mortals, to Asgard, the realm of the gods, which the gods travel daily to hold their councils and pass judgments at Urdarbrunn (Well of Urd) under the shade of the tree Yggdrasill. The bridge itself is the rainbow and its guardian is the god Heimdallr, whose hall of Himinbjorg is located at the upper end of the bridge. The red color was the flaming fire, which served as a defense against the giants. The bridge is destroyed at the end of the world, Ragnarök. It was built by the Æsir.
Much of what we know concerning Bifröst comes from Snorri (quoted below), but mention of it is also made in the Poetic Edda. For example, in Grímnismál, stanza 29 mentions Thor crossing over rivers (such as the Körmt and Örmt and the "Kerlaugs twain") which boil from the fire of Bifröst each day on his way to the judgement place at Yggdrasil, and later in stanza 44 it is named as the best of bridges in a list of the foremost of things (including Yggdrasil of trees, Sleipnir of horses, etc). In Fáfnismál, stanza 15 (as well as Snorri) indicates that it will collapse when ridden upon by the fire giants during the destruction of Ragnarök.
Some scholars, including Åke Ohlmarks and Franz Rolf Schröder thought that Bifröst may have originally represented the Milky Way and was reinterpreted by Snorri as a rainbow when confronted with variations in terminology.
His alternative names include Bilröst, Ásbrú, Bifrost (Danish, Norwegian and Swedish form).
The Prose Edda
In the Gylfaginning part of Snorri Sturluson's Prose Edda, there is a description of Bifröst:
- Þá mælti Gangleri: "Hver er leið til himins af jörðu?"
- Þá svarar Hár ok hló við: "Eigi er nú fróðliga spurt. Er þér eigi sagt þat at guðin gerðu brú til himins af jörðu, ok heitir Bifröst? Hana muntu sét hafa, kann vera at þat kallir þú regnboga. Hon er með þrim litum ok mjök sterk ok ger með list ok kunnáttu meiri en aðrar smíðir. Ok svá sem hon er sterk, þá mun hon brotna þá er Muspells megir fara ok ríða hana, ok svima hestar þeira yfir stórar ár. Svá koma þeir fram."
- Þá mælti Gangleri: "Eigi þótti mér goðin gera af trúnaði brúna, er hon skal brotna mega, er þau megu gera sem þau vilja."
- Þá mælti Hár: "Eigi eru goðin hallmælis verð fyrir þessa smíð. Góð brú er Bifröst, en engi hlutr er sá í þessum heimi er sér megi treystask þá er Muspells synir herja." - Eysteinn Björnsson's edition
- Then said Gangleri: "What is the way to heaven from earth?"
- Then Hárr answered, and laughed aloud: "Now, that is not wisely asked; has it not been told thee, that the gods made a bridge from earth to heaven, called Bifröst? Thou must have seen it; it may be that ye call it 'rainbow.' It is of three colors, and very strong, and made with cunning and with more magic art than other works of craftsmanship. But strong as it is, yet must it be broken, when the sons of Múspell shall go forth harrying and ride it, and swim their horses over great rivers; thus they shall proceed."
- Then said Gangleri: "To my thinking the gods did not build the bridge honestly, seeing that it could be broken, and they able to make it as they would."
- Then Hárr replied : "The gods are not deserving of reproof because of this work of skill: a good bridge is Bifröst, but nothing in this world is of such nature that it may be relied on when the sons of Múspell go a-harrying." - Brodeur's translation