Often, but not at all always unless you intentionally build it that way.

The Golden Gate Bridge, for example, extends from a hill on the northern end of San Francisco (elevation a little over 200 feet) to rugged high hills/low mountains on the southern end of Marin County (which top out at 800-1000 feet). To make it level, it has to target a specific spot on the Marin coastline, then go through a tunnel.

Most condom brands have them. They're fairly common in gas stations and most local retailers in my area. Usually the prices are about the same. I typically go with the lifestyles brand. It's usually about 5 bucks for a pack of 3

The sides of what you're bridging probably are.

Get an eye test or give up your licence.

> It's mainly because most features are relatively level.

If you're building a bridge you are by nature probably not dealing with level terrain.

Are spermicidal condoms more expensive than regular ones? Also, which companies manufacture them? I haven't seen any spermicidal condoms where I'm from.

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3rd hint: don't wear 2 condoms at once. They will break

There's really not much of a difference between them imo. I don't know if the ribbed actually make a difference for the girls but it doesn't matter for me. I usually go with spermicidal condoms though just in case.

How is it less complicated? We need new technology for that to happen. On the other hand we have trains right now. Tested and ready to go. There are all kinds of safety issues with having those trucks on public roads with other traffic which might mean they don't get approval any time soon.

Redshift changes the energy of the light but it still travels the same speed locally

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Life is created, presumably starting from one species. Then there's an explosion of life. Now all kinds of life. Some have fins. Some have feathers. Some have feet.

Some develop into something else, as different to the ones with fins as humans are. But that design fails. Better to have fins. Now they have fins.

Humans come along and see it and go hey, that's a fish.

But this 'fish' maybe used to be a lizard and then became a fish. So it went:

Step 1: ancestor

Step 2: something else

Step 3: something else

Step 4: lizard?

Step 5: fish?

Meanwhile, 'fish' #2 went:

Step 1: ancestor

Step 2: fish?

So you have one fish that came from a lizard and one fish that came from something else entirely. As a result, you have one fish that has a shared common ancestor with humans say maybe one billion years ago and another fish that has a shared common ancestor with humans three billion years ago. That means fish #1 and humans are related by one billion years while fish #1 and fish #2 are related by three billion years.

Conclusion: some fish are more closely related to humans than to other fish, and the category of fish is meaningless.

This is also true of crabs and trees. Mother nature proves to us over and over again that crabs, fish, and trees are the most superior earthly life forms.

All life started in the water. Imagine at some point two species of fish diverged from a common ancestor, species X and species Y. Both became ancestors to many subsequent species. Some descendant species of X (irl: lobe finned fish) eventually came to land, and that's where we descent from. Now, thousands of modern fish species have evolved from species X, and thousands have from species Y. A far descendant from species X might look morphologically similar to a species that evolved from Y (they are both "fish") but it shares a closer common ancestor with humans.

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Hypothetically you could make a machine that can self-replicate, but it would be on the level of complexity of many different fully automated factories, 3d printers would be one small part of such a machine.

Some things are just much easier to do with machining and grinding, like making linear rails to the required precision and surface finish.

Some things require completely different manufacturing processes, such as the electronics components.

There's also the issue of creating all the different materials required as input. You'd basically be automating a whole economy.

Great Eli5

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Thank you ❤️

I can relate to you a lot right now. We all have to start somewhere, you have to work your way up to the top. I will remember you