What the hell is spacetime?

It's everywhere

I started to write about the theoretical methods which might bring your great great great grandkids to the stars , when I realized I was getting ahead of myself. Before you can really understand what a worm hole is, or what a contracting/expanding bubble of space-time is, we needed to have a conversation about spacetime.

We all exist in Spacetime. You can't see spacetime directly, but it surrounds you, like The Force sort of, and it physically affects you every second.

This guy came up with the idea.

Edit: Not exactly. The fact is there were several scientists whose work all culminated in the current conception of spacetime. Einstein's special relativity was centrally important. But it was based in part on the prior work of Lorentz and Poincare. The spacial, geometric explanation of spacetime was actually formulated in 1908, building upon special relativity, by Hermann Minkowski. And, indeed, spacetime as we are referring to it here is known as "Minkowski Spacetime."

(Thank you @lemouth for pointing out the innacuracy! For real - if you see something wrong, or even near wrong, in my posts, let me know!)

Before this scientists considered the universe in two parts - one part was the 3 dimensional, physical part called Space. The other part was this thing that drags us all kicking and screaming to the grave, called Time.

After doing a lot of math I will never understand, a radical conclusion emerged:

Space and Time were not distinct but one cohesive four dimensional system called Spacetime

What does that mean?

Consider this slightly clearer picture.

The simplest way to conceptualize spacetime, for those of us who are not mathematically inclined, is as a flat mesh everything sits on top of. We don't really sit on it - we are actually immersed in it and constantly interact with it - but the "sitting" image is much easier to digest.

So, we're all sitting on this mesh called spacetime. Like the planet in the above picture, we all make dents in the mesh. The more mass something has - the heavier a thing is - the larger the dent.

So you or I make tiny tiny dents. But something big, like the Earth, makes a big dent, and the sun makes an even bigger dent.

This is also a simple way of visualizing gravity. Why do you and I not fly off the earth into space? Because we are so small that we have rolled into the big dent the earth makes in spacetime.

It also explains why the earth continues to circle the sun - the earth is rolling around the even larger dent the sun has made in space time.

For a much more in depth and really great explanation, you should watch this awesome video produced by PBS

Needless to say my explanation is all totally, bordering on deceptively, simplified. Spacetime is a mathematically profound concept which results in lots of strange effects - effects like time dilation, and the potential to warp or fold spacetime without breaking the laws of physics. But, for our purposes, broad strokes, this is the take away.

TLDR Spacetime is like a big mesh or sheet that everything in the universe sits on. The heavier the object, the more it dents or sinks into the mesh. These dents are a simple way to visualize gravity.

Now that we have that super basic understanding in place, we can talk about how humanity could theoretically use the nature of spacetime to move across the stars faster than the laws of physics would otherwise allow.

Next time on Piqued - Worm Holes and Warp Speed.

Image sources 1, 2, 3
Other source 4

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