Shortly after this picture was taken, we were on a float with my mother for the bicentennial parade. She made both our outfits of a (very itchy) polyester gabardine, and she wore a dress to match.

The apples my sister is holding meant something, but I don’t remember what and now I can’t ask her. I’d be very interested if anyone knows the significance of the apples during the US bicentennial.

I was 5 and my sister was 3.

I haven’t seen this with any other characters (lvl 46), but Sam Coe does this all the time. It’s so very creepy.

They’re both semi-feral and don’t always get along. Precious (the calico) doesn’t often have patience with her daughter, and Moppy (the big one) spooks at everything, real or imagined. I’ll never get another picture like this, so had to share.

Abstract

This paper is an enquiry into the logical, metaphysical, and physical possibility of time travel understood in the sense of the existence of closed worldlines that can be traced out by physical objects. We argue that none of the purported paradoxes rule out time travel either on grounds of logic or metaphysics. More relevantly, modern spacetime theories such as general relativity seem to permit models that feature closed worldlines. We discuss, in the context of Gödel's infamous argument for the ideality of time based on his eponymous spacetime, what this apparent physical possibility of time travel means. Furthermore, we review the recent literature on so-called time machines, i.e., of devices that produce closed worldlines where none would have existed otherwise. Finally, we investigate what the implications of the quantum behaviour of matter for the possibility of time travel might be and explicate in what sense time travel might be possible according to leading contenders for full quantum theories of gravity such as string theory and loop quantum gravity.

Proof this is a Bethesda game. It feels like home.

I’m no astrobiologist. Could be defensive or a mating display. Open to ideas.

1. There is a large philosophical literature on the first two paradoxes (and others), see, e.g., the entry on time travel, Wasserman (2018), and Effingham (2020), but very little on the easy knowledge paradox (emphasized by Deutsch 1991, discussed further below). Our approach differs from the literature surveyed in these two books by focusing on the physical—rather than metaphysical—possibility of time travel.

2. Multiple collisions are handled in the obvious way by continuity considerations: just continue straight lines through the collision point and identify which particle is which by their ordering in space.

3. The dynamics here is radically non-time-reversible. Indeed, the dynamics is deterministic in the future direction but not in the past direction.

[the rest won’t paste properly]

Interesting discussion by Christopher Smeenk.

I’ve got several replies in my inbox that I assume were deleted because when I click them I get an error message (or maybe it’s another bug, not sure), and I’d love to know whether they’re happening based on a certain reply, but I can’t tell.

It would be awesome if the community/threat were displayed in the header of messages in the inbox.

Thanks for all you do!

The first way we'll implement time travel will be sending data. First will be the equivalent of messages in a bottle – with no ability to choose the recipient – then we'll be able to send ordered data (the equivalent of texts, followed by voice/waves, then pictures/video, and eventually physical matter). We should currently be looking for rudimentary messages sent to us from the future, not trying to physically travel in time.

Adding dimensions to our understanding is a step towards navigating them. Time is the next logical dimension to understand (see, map, and navigate), and we can be fairly sure of this because we already travel in that dimension, though we don't yet have conscious control of our interactions within it. That means the time dimension interacts strongly with our native 3rd dimension (I mean strongly as opposed to weak interactions we can see with other particles in quantum physics).

Visualising that dimension will lead to navigation, though it won't become physically usable straight away. We should be looking for messages sent via data from the future, not trying to build a physical time machine.

A physical time machine as we've historically envisioned may not be possible, because the mechanism for moving through time in ways other than our standard vector may not have anything to do with the 3rd dimension that we're embedded within. Since time is likely a separate dimension from what we consider the third (and in which we're used to operating), a mechanism that allows us to travel in time will likely not be a 3rd dimensional 'machine'.

Visualising dimensions beyond our usual perception is the first step. If we can understand the structure of other dimensions and map out their rules, we increase the chance of being able to gain conscious control over them collectively. That would absolutely look like magic at first (in a similar way to lightning looking like magic to primitive people, but it's rooted in science that can be understood and manipulated), but it's nonetheless a real thing with properties and rules that we can understand and interact with. We already interact with it, albeit passively.

We move in one direction and see in the opposite. The first is our perception of the future; that's our normal vector. The second is our memory. We experience the highest fidelity at the point we call now, in which our local time point intersects strongly with at least 3 other dimensions. What we experience as the past is a perceptual gradient cone with less fidelity the farther it recedes from our 'current' perceptional point.

We should develop a receiver/detector first. We typically do this with properties of the universe which we observe, using physics and mathematics. Observation comes first, followed by documenting and testing rules, constants, variables, and formulas – that's how science works. Any observations and conclusions must make sense within the framework of existing physics.

Some preliminary questions include:

We each have a local reference frame as dictated by einsteinian physics in which time feels constant, and we know local perception isn't constant across the universe like, say, causality. We can define our local time using mathematical formulas, and we've explored some of its rules. We need to increase the fidelity of our understanding, defining more time rules, constants, variables, and formulas so we can properly design experiments.

Are there particles that link strongly to the time dimension? How are they structured? What are their underlying wave structures? What are their constants and properties? How can we express them using formulas? How do they interact with the other closest dimensional intersections or interfaces? How can we see or visualise them? How can we manipulate them?

What are the constants associated with our current vector? What formulas define our location and movement, and how can they be manipulated?

We need a receiver, like an analogue to the radio. We usually develop rudimentary receivers before we can fully map our understanding of a phenomenon. We likely already have enough knowledge to build one, like any other sensor we've developed. We just need to know what signal we're looking for. Assuming we've worked this out in the future, what's the simplest signal we should be looking for and how would we detect it? That should be our first step.

So the most intriguing question we can answer right now is: What would a message from the future look like, and how would we receive it?

E: I'm terrible at spelling apparently

I’m sorry if these are known issues, but I cant tell because of these issues. I can’t sort this sub in a way that helps.

I like to sort by new, but as of today I only see Top, Hot, Active, Most Comments, Most Comments (yes twice), New Comments, and Old. I want to sort the community by ‘new posts’, not new comments, but that’s no longer an option at all. Also, if I try to reload a few times, it crashes the app.

Not being able to sort by New Posts is pretty bad, and I’m hoping this wasn’t a design change (I assume it wasn’t, but since I can’t sort without the app crashing, I can’t tell what’s happening).

Thanks guys. I know you’re working hard and I appreciate everything you’re doing!