What is the Concept of Tenseless Space-Time?

[Ontophobe]

I've heard space-time described as 4-D and tenseless. The 4-D part I'm okay with, but I don't understand what tenseless means

 

[Vanadium 50]

And where have you heard this?

 

[HallsofIvy]

"Tenseless" means that, if you accept time as a coordinate just like x, y, and z, then you can observe "past", "now", and "future" at once just as you can observe "here" and "there". There would no concept of "past" and "future" so no "tenses" such as "were" or "will be".

 

[Nugatory]

One caution here: If someone states as a fact that "Spacetime is tenseless", and you ask them how that assertion could be tested (that is, whether there is any imaginable observation that would turn out differently according to whether the assertion were true or false)... Be prepared for a blank look.

That blank look tells you that we're talking philosophy not physics here. There's nothing wrong with that, but it may not help you much with understanding the physics.

 

[Ontophobe]

Thank you, Nugatory. This is important to me. So we can't come up with any experiments that could, in principle, falsify the claim that space-time is tenseless? This is exactly what the universe would look like if space-time were tenseless and this is exactly with it would look like if it were "tenseful?" If that's the case, then what was it that even put the idea in our heads that space-time is tenseless in the first place? Something in the math, I'm guessing. But what?

Oh and, I still don't know what "tenseless space" even is