It's not Chinese satellites that make the Doom reports, It's the first stage of their Long March rockets. They launch them up there without any means of a controlled de-orbit.

They're almost 50,000lbs, this old US satellite is only 5,400 lbs. Big difference.

You really hate to see “spacetime” reduced to a coordinate system like that. Imagine if you will a taut bed-sheet suspended in air by its four corners. You can think of each point of each fiber of that sheet as you classic xyz coordinate plane and the whole sheet stitched together as xyz-t incorporating time. The real revolutionary thing about this is that spacetime as the fabric of space interacts with matter creating the effect of gravity. Balls of mass sitting on the sheet locally deform the entire sheet causing anything sitting on that sheet to “fall” toward it. The bigger the mass the bigger the effect. It also shows how the effect can be universal (all mass is attracted to other mass) but the magnitude of this attraction is a function of the magnitude of the deformation and another mass’s distance to the deformation. It is one of the non purely math only explanations of what a “force” is.

Hello u/Dusthip, your submission "Can someone explain what spacetime is?" has been removed from r/space because:

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There’s a really good explanation of the twelve dimensions of reality on YouTube, trying to make sense of the relativity and reality. I can’t find it right now due to bandwidth issues but you can search around and find it.

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It’s bizarre to me that an American satellite potentially falling onto inhabited areas gets treated like it’s a coworker’s funeral, but a Chinese satellite doing the same gets treated like it’s a deadly act of war or something. Really makes you think.

It brought a tear to my eyes when I saw Atlantis at Kennedy back in 2017, I only ever saw 1 shuttle launch and that was back in 2000 and it was Atlantis I saw launch.

My brother and I had a trip to Florida and showed up an hour till closing and the guy at the front said if you wanna see anything go see that exhibit. The show, the walk around and all the cool segments around the ship made it all worth the money. Icing on the cake we went and ate at a restaurant on the water that night and space x was doing a launch and we got to see that while eating to our surprise. Best night of that vacation.

Some cultures have patterns in the dark spots as there are too much stars

Here's the simplist, most practical way to visualize the theory. You're in a conversation with a close, but very dense relative. Notice the way time slows to a standstill? That's relativity.

movement through space and time are inversely connected, the faster you move through one the slower you move through the other. at 99% c you experience time very slow, but to experience time at full speed you have to be moving very slowly. This is all relative between objects because there is no mathematical 0,0,0 point we can anchor ourselves to in a universe where everything is moving. not experienced with this at all so definitely tell me if i'm wrong

That looks amazing. It's disappointing that the shuttle at the Udvar Hazy is just sitting there. The shuttle at Kenney in Florida, you can walk through and even look into the crew compartments. I really wished they'd open all of them up to look inside. Heck, it would still be cool, even if they were partly stripped.

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I cried the first time I visited the Atlantis exhibit. The video shown before entry is awe inspiring.

Fun fact: the orbiter is mounted at a 32.1º tilt, a nod to the countdown heard at KSC.

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Space and Time: Let us meet in Time Square (New York City, USA) at 1200UTC.

It is the simplest set of spacetime continuum coordinates. Omitting space or time, you miss a date ;)

Let’s say I have a frictionless ball, I drop the ball and it bounces back to my hand exactly into its original position (because it is frictionless). However me and the ball are on Earth, which is rotating and which orbits the Sun, so me and the ball have actually moved significantly from where we were when I dropped the ball. You can go even further than this and think about how the Solar system moves through the Milky Way, which itself is also moving etc. So did the ball bounce back to its original position? You might say no, but that’s only because you have other objects as a reference point, if you could not see them you would have no idea.

The point is there is no absolute space. You can’t describe a point in space without also describing a point in time (or another object, but then it has the same issue of needing its own time coordinate or another relative object, then the issue repeats). The same goes for describing a point in time without describing a point in space, although this is harder to grasp.

We actually already think like this in our day to day lives, in fact humans are very unique for thinking this way. For example, do you show up at work simply at a specific place? Or do you show up for work at a specific place, and at a specific time?

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Basically. There is no up down left or right in space, the massive object is warping in 3 dimensions, not just a 2D sheet.

'Dead' is kind of harsh. We like to call it 'gone to make a crater on a nice farm in the country.'

Remember Isaac Newton? Newton is responsible for large portions of the the physics that is really useful in our day-to-day lives. For example, Newton's laws of motion offer a foundation upon which we can understand inertia, the relationship between force and acceleration, and how two objects will interact with each other if one hits the other.

The formulas that Newton (and others) developed are still used today in many fields, and all of this math treats space and time separately. We call this classical physics. So why do we need space-time at all if these formulas work for so many day-to-day applications?

As velocity increases, the formulas used in classical physics start to become inaccurate. This happens because our physical world is not absolute, but relative. Without considering these relativistic effects, the calculations made using Newtonian physics result in errors.

The new formulas developed as part of relativistic physics lead to the coupling of space & time as a way to make the calculations for accurate measurements and predictions easier.

If you have a few minutes, there are two short videos available from TED-Ed that explain space-time using simple animations. Their explanation is very accessible, and is broken down into 5 minute segments.

Part 1: https://www.youtube.com/watch?v=ScdLqAA_64E

Part 2: https://www.youtube.com/watch?v=aeCsS6PjhK8

Part 3: https://www.youtube.com/watch?v=NAXHHBUY9_E

When conceptualizing spacetime does the sheet only represent a "slice" of spacetime in the analog? If so, could you take the same concept and represent it as a weighted sphere embedded in a large sponge, with the sphere causing the sponge to sag? The sponge would sag more in the immediate area of the sphere and less so as you move away from the sphere?

Right, time allows changes to occur in the three spatial dimensions.

The fourth dimension allows for change to occur in the three former spatial dimensions. This is spacetime.