People Share Their Favorite Scientific Paradoxes

"You receive..."

The Bootstrap Paradox

You receive a strange machine and a note that says "This is a time machine, recreate the time machine and send the machine back in time to the day you received it (today)." Bewildered, you set to work to recreate the time machine. When you are done and have tested it, you send the original machine and the note back in time to the day you received it.

You didn't create the machine you received from yourself, where did it come from?

Artemy_fluffball

"Could Jesus..."

The Homer Simpson paradox: Could Jesus microwave a burrito so hot that he himself could not eat it?

Utegenthal

"Side A..."

The Paper Message

Side A: The message on the other side is the truth

Side B: The message on the other side is a lie.

radabdivin

"Camus..."

Camus regards The Absurd as a paradox. Humans are constantly driven to seek meaning in a world that doesn't appear to have any.

VanFailin

"The sequence..."

The Galileo paradox

The sequence of square numbers: 1, 4, 9, 16, 25, 36, 49, 64, etc clearly shows that there are a lot fewer square numbers than there are non-square numbers, as the distance between them gets increasingly longer.

But any number can be multiplied by itself and the result of this multiplication is a square number. So it must also be true that there are at least as many square numbers than there are non-square numbers.

scenesequel

"Mine is..."

Mine is probably Zeno's Dichotomy paradox although having a favourite paradox is a weird thing.

This one is basically that to reach a certain distance you have to reach half way first. So if the door is 10m away you first have to reach 5m then after that 2.5m then 1.25 and so on and so on which means you will never reach the door.

The other one is The Ship of Theseus, also known as Theseus's paradox. Sometimes also known as the Axe paradox.

The axe version is that if you are given an Axe and replace the wooden handle is it the same axe? What if you then replace the blade? How many times can you repeat this process before the Axe is no longer the same Axe?

Alternatively the ship paradox is similar in that if you replace every part of the ship is it the same ship or a different ship?

Raises the question of identity.

The cool thing about this is that your entire body is made up of a different set of cells every 7 years or so (as cells die). So can you really say you're the same person you were 7 years ago?

iRRVi

"Yes I know..."

Swiss Cheese Paradox

Swiss cheese as we all know has holes. Therefore, the more Swiss cheese you have, the more holes you have. However, the more holes you have, the less cheese you have because of it. In conclusion, the more cheese you have the less cheese you have.

Yes I know it's a joke paradox. I still love it because how stupid it is.

Mowzak2k

"There is a..."

There is a smallest number that is not nameable in less than 18 syllables. But "The smallest number not nameable in less than 18 syllables" has seventeen syllables and names the same number.

gregbard

"How 0.9..."

How 0.9 repeating is equal to 1 There's lots of different ways to prove it but the simplest for me is this example:

X = 0.9999... Multiply it by 10, so 10X = 9.9999... Subtract 1X from 10X or 9.999... - 0.9999... which equals 9 So then 9X = 9, simplify to X = 1

I was in denial for a good bit when I first heard of this.

Lilwashcloth

"It's basically..."

The Fermi Paradox

It's basically about the existence of aliens and can be summed up as:

"1- The Milky Way contains hundreds of billions of stars, and billions of them are similar to the sun.

2- It is highly likely that some of these stars will have planets that are similar to Earth.

3- If we assume – via the Copernican principle – that Earth is not particularly special, then intelligent life should also exist on some fraction of these Earth-like planets.

4- Some of these intelligent life-forms might develop advanced technology, and even interstellar travel.

5- Interstellar travel would take a long time, but as there are many sun-like stars that are billions of years older, there has been plenty of time for such travel to have occurred.

6- Given all this, why haven't we met or seen any trace of aliens? Where is everybody?"

NiceHouseGoodTea