Why did the CIA secretly buy Soviet metal to build the very plane designed to spy on them? How does a metal named after Greek Titans manage to fuse physically with living human bone? If titanium is the ninth-most abundant element on Earth, why is it still so expensive to produce? And how did common chlorinated tap water nearly destroy the manufacturing of the world’s fastest titanium jet?

... we explain like I'm five

Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: mattau93, bigaddam, barath_s, icowboy, justscottaustin, 1fresco, qininator and cheapseats91

To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter:

https://www.twitter.com/eli5ThePodcast/

or send us an e-mail:

[email protected]

Why do people in the UK typically say Happy Christmas while in America it is most commonly Merry Christmas? What made red and green Christmas colors? Is it true that Coca-Cola popularized the modern look of Santa Claus? Why do most of our "traditional" Christmas songs, images and TV/movies come from the 1940s to the 1960s? Brian Earl from the Christmas Past podcast joins us to ELI5 a range of Xmas questions.

... and we explain like i'm five!

Help more people fund us by leaving a rating on iTunes.

Thank you to Brian Earl from the Christmas Past podcast. If you'd like to hear more excellent xmas episodes, check out Brian's podcast here:

https://christmaspast.media/

To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter:

https://www.twitter.com/eli5ThePodcast/

or send us an e-mail:

[email protected]

Why do people in the UK typically say Happy Christmas while in America it is most commonly Merry Christmas? What made red and green Christmas colors? Is it true that Coca-Cola popularized the modern look of Santa Claus? Why do most of our "traditional" Christmas songs, images and TV/movies come from the 1940s to the 1960s? Brian Earl from the Christmas Past podcast joins us to ELI5 a range of Xmas questions.

... and we explain like i'm five!

Help more people fund us by leaving a rating on iTunes.

Thank you to Brian Earl from the Christmas Past podcast. If you'd like to hear more excellent xmas episodes, check out Brian's podcast here:

https://christmaspast.media/

To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter:

https://www.twitter.com/eli5ThePodcast/

or send us an e-mail:

[email protected]

What makes a pearl so mesmerizing, and what is it really? What exactly is a pearl made of, and how does it form inside a mollusk? Can a grain of sand truly cause a perfect pearl? What's the difference between a natural pearl and the cultured ones we see today? How do pearls get their stunning array of colors, from soft pinks to deep blacks? What makes certain pearls incredibly valuable, fetching millions?

... we explain like I'm five

Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: emoposer, iamkunii, cooldrummer1208, Albres, discordant_rhyme, xentonian, enzio901, n19h7m4r3

To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter:

https://www.twitter.com/eli5ThePodcast/

or send us an e-mail:

[email protected]

If every major country is in billions of debt, where are they borrowing from? Who exactly do they owe? Are there any consequences for them being in debt? Why is it a problem when it gets large? Why was Greece in trouble, while Japan seemingly has high debt but is fine?

... We explain like i'm five!

Help more people fund us by leaving a rating on iTunes.

Thank you to the r/explainlikeimfive community, and specifically the following reddit users whose questions and responses formed the basis of this conversation: emils5, poomanshu, potato_octopi, cop-disliker69, reshkayden, agoraiosbum, cheesewithwhine, aythekay & anjabe96

To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter:

https://www.twitter.com/eli5ThePodcast/

or send us an e-mail:

[email protected]

Did you know bubble gum is traditionally pink simply because the inventor ran out of every other color? Did McDonald’s really try to help kids eat healthier by inventing bubble gum-flavored broccoli? What actually sets bubble gum apart from regular chewing gum?

... we explain like I'm five

Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: dart_catcher, shaka_sulu, bluehellebore, tato7069, ted_normal and charlzpatton

To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter:

https://www.twitter.com/eli5ThePodcast/

or send us an e-mail:

[email protected]

What sparked the invention of Morse code, and how did personal tragedy influence Samuel Morse's creation? Is Morse code still used today? How does Morse code rely on timing, and what role do dits and dahs play in understanding messages? Why do some people still feel a connection to Morse code today despite advances in communication technology? How did WWII utilize Morse code for encrypted communications, and what were the implications for message security?

... we explain like I'm five

Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: stanitor, appropriate_trader, effective-ad-6460, twin_spoons, scotterson34, idealblueman, hipp013, beachedwhale1945.

To the community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter:

https://www.twitter.com/eli5ThePodcast/

or send us an e-mail:

[email protected]

What makes marble feel cold to the touch, especially in winter apartments? How does the use of marble in art reflect the cultural values of the civilizations that employed it? What exactly is marble and how is it formed geologically? What role does marble play in ancient Greek architecture, specifically in the Acropolis and its iconic structures? How does the history of marble reveal about human ambition, creativity, and the pursuit of perfection?

... we explain like I'm five

Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: reynardb, razeus, pierre_poutine90, forkwhilef0rk, sgrams04, stevewmn, rundna, thaddeusjp.

To the community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter:

https://www.twitter.com/eli5ThePodcast/

or send us an e-mail:

[email protected]

Why do modern carriers feature an angled flight deck instead of a straight full-length runway like their WWII predecessors? How fast does an aircraft have to go to take off from a carrier? Why don't planes just fall off the front of the ship when they take off? What are the costs and challenges associated with building longer runways on aircraft carriers? What advantages do nuclear-powered aircraft carriers have over conventional ones in terms of operational efficiency? 

... we explain like I'm five

Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: hyndis, green_meklar, kal_vas_flam, infernalism, pedopaul, aquatic_mammal, amatulic, generallyawfulhuman.

To the community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter:

https://www.twitter.com/eli5ThePodcast/

or send us an e-mail:

[email protected]

Is the Iron in our body different from the Iron used in construction? How did ancient cultures use meteoric iron without knowledge of metallurgy? What makes iron such a vital natural resource throughout human history? Why doesn’t iron in our blood react strongly to MRI machines? How does the imaginative concept of ""space swords"" link history and modern mythology around iron?

... we explain like I'm five

Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: azhiker00, 18_usc_47, dependent_warning_51, lallo-the-long, boredcop, gnonthgol, gailynstarfire, 1strategist1.

To the community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter:

https://www.twitter.com/eli5ThePodcast/

or send us an e-mail:

[email protected]