It's worth noting here that the modern 365-day calendar is somewhat recent.

Many older cultures - notably, both the Jews and Chinese, who retain their older calendars - were what are called "Lunisolar" calendars. In these calendars, you have a set cycle of months, and introduce a leap month into the calendar if a specific month would happen before some yearly event. While I can't find that for the Chinese Calendar right now, the Hebrew calendar is normally 354 days, but adds a 13th leap month if the new year would start before the Spring Equinox.

Other people have already described how these people determined the solstices; and the equinoxes are pretty easy to figure out as well (halfway between the solstices - both in terms of time; and in terms of where the sun rises/sets).

Your submission has been removed for the following reason(s):

ELI5 is not for discussion of fiction, gaming, fantasy, etc. These discussion are inherently subjective and often lead to flame wars. There are plenty of venues for that on Reddit; this is not one.

If you would like this removal reviewed, please read the detailed rules first. **If you believe it was removed erroneously, explain why using this form and we will review your submission.

Another explanation is that the more space between 2 galaxies, the more that space expands. Say you have 12 ft of rope. Every 5 minutes is expands by 1 in per foot. After the first cycle you have 13 ft of rope After the 2nd, 14ft 1in After the 3rd, 15ft ~3in The longer the rope, the faster it expands.

In simple terms, there's a chemical in the cells of the retina that turns light into nerve impulses. It gets used up doing so but is constantly being regenerated. With bright lights too much gets used and it takes a while for the regeneration process to replenish the stock before those particular cells can respond properly to light again. In the meantime the nerves from those parts of the retina transmit random signals to the visual part of the brain.

The way he explains it is actually pretty good.

Replacing it with actual numbers:

You live in 2020.

You go back to 2000.

In that case, events in the past (2000 to 2020) caused you to do an action (go back in time).

Once you're back there, though, time still works the same way it always did. Events in the past can cause an effect in the future, but tomorrow isn't ever going to directly change today.

So, once you're back in 2000... the events of 2020, which to you are in the past (because you remember going back in time and everything that happened before that), can change your future actions (which to you take place in the year 2000). That means that if you can go back in time to change the past, you can change the past: your actions in your immediate future can cause changes.

But, the future can't change the past. If you went back to 2000 and did something there that made you not have to do that in 2020... well, you still did do that in 2020, because how else would you have been in 2000 changing things?

The idea is that once you go back in time, any changes you make are focused on the way you experience time, not some third-party objective time.

OP might be confusing a high elastic modulus with a high [yield](https://en.wikipedia.org/wiki/Yield_(engineering)) point. In this case, since wood is a relatively stiff material, it will yield long before it deforms by very much (here's a table with yield strengths for wood boards).

To rephrase for OP: the elastic modulus tells you how much wood deforms, but it doesn't tell you anything about when it will bend out of shape permanently or break. A wood board can't support 450 cars, but not because it gets squashed, because the load exceeds the yield strength of wood.

Are you talking about the "leftover" spots after you look away from the bright thing?

The technical term for this is an afterimage. It's mostly caused by your brain compensating for the bright stimulation of the light. Basically, your brain is looking for contrasts, and it assumes that most of your visual field "should" be at a similar brightness, so it adjusts very bright spots down in brightness in a way that lingers for a short time. (Another, smaller, contributor is that the cells in the retina - the light sensitive part of your eye - can only be stimulated so often, and a very bright light can easily saturate all of those cells so that they're effectively "disabled" for a few seconds.)

Picture a 3x3 grid of pixels like this:

O O O
O O O
O O O

How would you color in those pixels to draw a complex shape like the letter "P"? You really can't. No matter which way you choose to draw it, you'll either be missing the bottom of the stem, the hole in the middle, or something else. Similarly if we were to try and draw a diagonal line "\" it would have to be stair-stepped.

Computers try to get around this by doing something called "anti-aliasing," which adds translucent pixels around the edges, but it's more of a bandaid for the problem since it relies on the computer trying to guess about missing information, and often results it trade offs like smoother edges but tiny details vanish since they are too small to be rendered in the first place. By rendering at a higher resolution and then scaling down, we can render all the extra detail that needs to be there, and then scale down to get an "accurate," image.

Also in the top layers the algae is thick an blocks sunlight from reaching the bottom layers where decomposition is taking place, so it's even more so pronounced.

Its easier to understand if you remove color and shades, and just consider a similar black and white image. With this, the screen is just a bunch of dots in a grid. If you have something going diagonally across them, such as a triangle, you have to decide which dots to turn on and which to turn off. This means you end up with a choppy looking pattern:

   ■
  ■■
 ■■■
■■■■

If you can also show gray colors, you can render that line at a higher resolution and average the values of each small block, resulting in gray near the line and a much smoother image. The more averaging you do, the better the end result will be, and this is why 8x looks better than 4x and so forth.

This is known as super sample antialiasing (SSAA). There are other methods to achieve similar results with various benefits and drawbacks:

Temporal antialiasing (TAA) which averages between multiple frames with slightly different camera angles. This one was made well known by Unreal Engine 4.

Another is called Fast Approximate Antialiasing (FXAA), which uses some image recognition-style techniques (a severe simplification) to find the jagged lines and blur them.

Wanna bet?

Karahan Tepe, Turkey, the oldest known ancient site accurately aligned to the winter solstice is over 11,000 years old.

There is a site in Aberdeenshire, Scotland, with a lunar calendar that used the solstice to keep on track that is about 10,000 years old, though it is not nearly so sophisticated.

There are a number of sites in Great Britain, Mesopotamia, and at least one in Germany aligned with the solstice which are as old or older than the pyramids.

The ancient Egyptians tracked more than 4,000 astronomical events. There are a number of examples of ancient calendars and structures that were aligned with the solstice created by the Egyptians, such as the Sphinx.

Heard of Stonehenge? Tracked quite a bit more than the winter solstice. Not that old considering it appears to be 7,000 years younger than the oldest known example.

If going by technology rather than age, then in the New World, we have Machu Picchu, Chichen Itza, Chaco Canyon, and quite a few others.

Scientific method? Not required. Not even close. Not even Neolithic. Mesolithic. Some of these structures were built prior to the most recent period of the Stone Age.

[removed]

So it's impossible to halt this process, as we would need to correct every single cromossome. Am I correct?

However if that is true then why the son from a man in his 60s doesn't borns old? Better, how didn't we start to degenerate after the few generations from the first living being, as DNA is always mutating.

Pardon from my ignorance If I talked something wrong.

Building off what other people have said about humans and our ability to discern each other so well - Our abilities suffer greatly if we even attempt to reliably see the difference between people of ethnicities outside of our environment’s norm/majority. I can’t remember exactly what the source was, but I watched a shocking documentary on how many black people in America were convicted by white juries based on witness accounts saying “yes it was them, they did it I saw them!” And later released based on actual evidence proving they could not have committed the crime.

Modulus of elasticity is the relationship between applied stress, and strain.

If you try to bend wood by applying force to it, you are applying a stress, and the amount that it bends is called the strain. 1.8 million PSI is not actually that high of a modulus of elasticity, considering steel's is more like 30 million PSI.

Basically it tells you that wood is resistant to being deformed - but steel is significantly more resistant to being deformed.

I have no idea what you're talking about. If I look at photos of the sun sometimes I see orbs stretching out from it but I don't see them normally. What should I do to try seeing them?

That's one example. It makes quite a difference tho, 6%. Also, whether you should call or not would depend on the bet size and the pot size. Getting slightly over 4 to 1 would be break even, not considering implied odds.

In the MCU, the way that time travel works is different than, say, Back to the Future. All time travel stories kind of make up their own rules.

When the Avengers time traveled, they basically just jumped into a different universe, at the time and place where they wanted to be. So they go from Universe A to Universe B, and then when they want to go home, they can bounce back to Universe A So nothing they did in that different universe would directly affect their current universe. If they went to some random person's house (John Smith) in Universe B and killed him, for example, that wouldn't affect Universe A John Smith at all.

So no matter how much trouble they got into in their mission, nothing they could do in any of those parallel worlds would affect Universe A. Except, as it turns out, that they managed to let the bad guys from another world come into Universe A, and that caused some issues.

The cells in our body are constantly replicating themselves. During the replication process, DNA is copied and pasted for the new cell. The copying and pasting process doesn’t always go right and sometimes you run into mutations. Aging is a part of this DNA mutation phenomenon. As more things go wrong, your body slows down and becomes weaker. This along with all the physical stress your body goes through on its life.

Causal loop basically the reason for your travel back into the past no longer exists if you "cure" what happened in the past so there is no longer a reason to travel back to fix something, and if you don't fix it it stays the way it was.

He's suggesting (rather correctly) that time is relative. He's also suggesting that time is subjective (again, kinda correct).

Everything that you haven't done yet is in your future, no matter when in the rest of the flow of time that occurs. Everything that has already happened to you is in your past and therefore immutable for you. Is what He's trying to tell them. By going "back in time" they will be changing their present, not their own past.

What we can say is that particles travelling at c can not change state, hence the puzzlement in the 20th century about "missing" solar neutrinos.

"Can't experience change" is something we might describe as "time does not pass", without implying they have a reference frame.

Time travel is fictional. There's no actual rules to how it works, so any story you see it in will have different rules depending on what that writer believes would make for a more interesting story.

In that film, they're not using the idea that you can go back in time and change the future. Instead, they're saying that when you travel back in time you create an alternate timeline, a different future where events played out differently because of your actions in the past.

So in that story, it doesn't matter if you go back in time, you can't change the future you came from. You've just created a different future where a different version of you will live.

The danger zone thing is where it kinda gets lost though. For example:

My parents get half a cow each year. Someone mixed some stuff up and put a chunk of the burgers in the fridge instead of the freezer. Well, the fridge was still below 40F (basement fridge is set pretty low) so the meat thawed but didn't hit the danger zone.

The rest of the family still living there were put off by it, so unless he cooked it without them seeing they didn't want it. So he gave me the thawed + refrozen ones. They're just fine.

Since it's just me and my wife, it's hard to get through 8 burgers fast enough. We just don't eat beef like that. Normally when we got a few packs they weren't thawed so we could just break the package in half due to the way it was packaged and thaw that half. If I was sure I could even break that in half and only take out the two we wanted to eat.

Well since these thawed I can't do that at all. They kinda squished together. So a few times now I put them in the fridge until they're thawed enough to break apart (or nearly completely thawed if doing it overnight) and then repacking them in batches of 2 to refreeze.

Two thaws, two refreezes, doesn't matter. Sure they might spoil a little faster if I leave them in the fridge now.... But it doesn't really matter.

Please read this entire message

Your submission has been removed for the following reason(s):

• ELI5 requires that you search the ELI5 subreddit for your topic before posting. Users will often either find a thread that meets their needs or find that their question might qualify for an exception to rule 7. Please see this wiki entry for more details (Rule 7).

If you would like this removal reviewed, please read the detailed rules first. If you believe this submission was removed erroneously, please use this form and we will review your submission.