# Put two same solid materials next to each other and they combine into one without liquid transition?

**URL:** <https://boards.straightdope.com/t/put-two-same-solid-materials-next-to-each-other-and-they-combine-into-one-without-liquid-transition/838314>\
**Category:** Factual Questions\
**Created:** [August 7, 2019, 8:04pm UTC](https://boards.straightdope.com/t/put-two-same-solid-materials-next-to-each-other-and-they-combine-into-one-without-liquid-transition/838314 "2019-08-07T20:04:37Z")\
**Posts on this page:** 4\
**Page:** 2

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**Author:** ![Isamu](https://avatars.discourse-cdn.com/v4/letter/i/7c8e57/32.png) [@Isamu](https://boards.straightdope.com/u/Isamu)\
**Post date:** [August 11, 2019, 12:21pm UTC](https://boards.straightdope.com/t/put-two-same-solid-materials-next-to-each-other-and-they-combine-into-one-without-liquid-transition/838314/21 "2019-08-11T12:21:05Z")

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Is this what is happening with gold and silver coins that have been lost in shipwrecks and when recovered centuries later have formed a mass of metal that is joined together but doesn’t look “melted” per se? Like this:

> **[Taj Mahal Sunken Treasure 1702](https://cannonbeachtreasure.com/pages/taj-mahal-sunken-treasure)**
>
> Coins "Like the Shining Full Moon in the World"Just over three hundred years ago, an Indian trader sailed from the bustling port of Surat, India, bound for the Far East via “the Spice Route.” She carried a treasure to satiate desire: bag after bag,...

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**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\
**Post date:** [August 11, 2019, 2:37pm UTC](https://boards.straightdope.com/t/put-two-same-solid-materials-next-to-each-other-and-they-combine-into-one-without-liquid-transition/838314/22 "2019-08-11T14:37:20Z")

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> [@Napier](#):
>
> I think, on a geological time scale, different kinds of rock diffuse into one another while very much into the solid state.

I’m blanking on the name but there are small spherical stones that have been discrete objects separate from the surrounding rock for in some cases _billions_ of years.

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**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\
**Post date:** [August 11, 2019, 3:34pm UTC](https://boards.straightdope.com/t/put-two-same-solid-materials-next-to-each-other-and-they-combine-into-one-without-liquid-transition/838314/23 "2019-08-11T15:34:43Z")

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Others have mentioned gauge blocks that are wrung together.

I once read an article (sorry, no cite) that said physicists still do not understand the physical mechanism for why gauge blocks stick together.

The article said it was not due to Van Der Waal Forces. It also said it was not due to air pressure, since experiments have shown gauge blocks can be wrung together in a vacuum.

According to the article, the only explanation to-date is “molecular forces.”

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**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\
**Post date:** [August 11, 2019, 8:10pm UTC](https://boards.straightdope.com/t/put-two-same-solid-materials-next-to-each-other-and-they-combine-into-one-without-liquid-transition/838314/24 "2019-08-11T20:10:00Z")

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Is Casimir force a factor?

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