# Boltzmannbrain

Senior Members

240

## Recent Profile Visitors

1007 profile views

0

1. ## Why is it so hard to explain time? (What is time?)

We know a lot of properties that time has. Importantly, we can use this knowledge to make almost any prediction that we need. In this sense, it really don't think time is very mysterious. And I think one thing that seems mysterious to people, is that we can't see into the past or future like we can with space (it is spacetime, but I will call it space to be less confusing). But general relativity came along and showed us a geometry of spacetime that is very accurate. In this geometry, the photons have such angles that only carry information from space, not time. It is kind of like being partially blind, and you can only see in certain directions. However, I think that there is a very big mystery to be solved about time. It is a dimension that we are automatically travelling through at the speed of light instead of having various speeds in the spatial directions. How is this happening?
2. ## Time travel is not logically possible

Where did I say you can?
3. ## Time travel is not logically possible

I wasn't sure what you knew. That is why I simplified it to spatial distance. However, I did add that it is a different kind of metric than Euclidean. The idea is practically the same. The spacetime interval for the coffee cup is s^2 = - (ct)^2, x^2, y^2, z^2 = - (3x10^8m/s*1s)^2, 0, 0 , 0. I am just trying to explain it to you the best I can. The only reason why the coffee hadn't spilled in your present is because of the angle that your present occupies in spacetime. It is in the present of other frames because their presents in spacetime are at a different angle.
4. ## Time travel is not logically possible

Imagine you are looking at a typical coffee table. It's measurements are not important, but let's say it's 2 meters long, 1 meter wide and 1/2 meter high. Does this object have a past, future or present? Of course not, it is just an object. In one second, this coffee table extends through the 4th dimension. Now let's isolate this coffee table again. It is now an object measuring 2m x 1m x 0.5m x 300,000,000m (remember the coffee table went through 1 second of time). *this is of course uses the Minkowski metric which is different metric than Euclidean metric, but the idea is the same. At the beginning of the second, the coffee table was in our present. But for someone or something else travelling at a certain speed, the coffee table at the end of the second is in their present. We are all correct GR. The reason why the coffee table had a past, present and future is because we say it does; that's it. Imagine that someone spills a coffee at the end of that second. If we are at the beginning of that second, there will be other frames of reference where the coffee was already spilled. Of course they can't communicate to us that this will happen, but it happens in their present nonetheless. So if the coffee spills at what may be an infinite number of "presents" in the universe, what or who is to say that it should have a present at all. Or a past or a future. It (along with the rest of the universe) just exists eternally in GR.
5. ## Time travel is not logically possible

If you watched the video or truly understand GR, you would know that there is really only one option.
6. ## Time travel is not logically possible

I didn't say it was a complete theory. This thread is about my claim that time travel is not possible with GR. It tells me that you agree with me that time machines are possible, at least theoretically. But I am not only saying that it is unknown whether or not they are possible, I am flat out saying that they are impossible. I gave my reasons in the OP. It makes no sense to even talk about them in GR (except to say that they make no sense). Take a 1 dimensional particle that lasts for 5 seconds for example. Assume there is no force applied to it so that its worldline looks like a long straight 2 dimensional line on a spacetime diagram. In GR, this line doesn't have a past, present or future; it just simply exists. Past, present and future are human constructs. They are concepts in the mind. Since everything is made up of these eternal particles, so is the universe. What if advanced aliens built a time everyday for the past 10,000 years, and they have them, oh I don't know, under some mountains? It allows a lot of opportunity to do illogical things like change the past.

8. ## Time travel is not logically possible

I took the first reference that came up because this is not what I had expected to have to defend. from https://www.usatoday.com/story/tech/science/2022/09/10/time-travel-possible-science/7847346001/
9. ## Time travel is not logically possible

So your response is that my logic isn't good, but you don't say why. Okay, you have my ear, so please tell me what part of my logic is not up to your standards. And this just tells me that you don't know much about this topic.
10. ## Time travel is not logically possible

Time travel is not logically possible if we assume Einstein's theory of relativity is more or less the true explanation of the universe. Einstein's theory of relativity implies a block universe, which is to say that the future already exists, and the past still exists. Ultimately, the universe is a 4d structure that doesn't change. And as far as we know, this entire structure doesn't age in another temporal dimension, and it doesn't exist inside of another spacial dimension either - it simply just exists. Now for an example of the illogical idea of time travel. Imagine that it is the 3rd of January at 11:00pm. You are alone in your house. A week later you have the opportunity to travel back in time (somehow). You decide to visit yourself on the 3rd of January at 11:00pm. Structurally speaking, what happened here, how did this static 4d structure (the universe) change? How can a nonmechanical structure just change itself from being A to being B? Moreover how is it logical that the universe has only you in your house and also has two of you in your house? From what I understand, the universe is made up of events that have their set x,y,z,t locations in spacetime. None of these events move, and none of them appear or disappear. Everything just is the way it is. In general, nothing physical actually changes or moves (I put "physical" because you could argue that a nonphysical consciousness moves through the human parts of this structure, but that's a whole other discussion). How is time travel logically possible?
11. ## Do gravitational waves distort time?

Yes, I would definitely think that the detector would read a dilation of time. A precise clock should breifly slow *slightly* as the wave passes. A gravitational wave comes from the acceleration of mass. This would seem to mean that a gravitational wave would cause a very brief moment of gravitational increase and decrease to the detector. So depending on how strong the wave is, it would be just like a mass existing for a brief period and then disappearinas at the detector. And I would think that this must cause a brief time dilation as well. A question I find interesting is what is the trough of a gravitational wave? If the crest is a brief pull with time dilation, is the trough a push with time "expansion"? Is it a sort of moment of anti gravity or dark energy? I am very much open to critique by anyone if what I said is nonsense.
12. ## How can a big bang expand to an infinite size?

I already posted it. It's a simple equation of many to choose from. Something like 1/(1 - t) would work.
13. ## How can a big bang expand to an infinite size?

This is interesting, but I have no idea how this is an example of Markus' explanation. Please explain.
14. ## Mind

The evidence points to the consciousness constrained to being just a property of the brain. We know this because of the correlations found so far between mind and brain. And there is practically no evidence (that I am aware of) suggesting otherwise. My post was defending the idea that the mind is an immaterial property of the brain and not a physical one. I was reading your discussion with the other poster, and it seemed you both thought an immaterial mind was a bad idea. This is why I made my post. To answer your question, no, I definitely was not saying that the mind has the ability to do otherwise than what the brain does. So far, there only seems to be a one-to-one correlation between mind and body. My personal opinion is that I am still not sure, but I am leaning towards epiphenomenalism (mind-body being fully correlated). But I don't think we know enough for me to make a hard claim yet.
15. ## Mind

The mind being an immaterial property of the brain might not be as woo as it sounds. I personally think this is where the evidence and lack of evidence is pointing to. It also explains philosophical zombies. If there were two identical people each living on identical planets doing identical things and one had a mind and the other didn't; the one that doesn't is the "zombie". We would never know which has the mind, even by looking at every particle in both people. The physical makeup is identical. The mind would not have any autonomy in the person versus the zombie. Then you may say, well maybe in reality there is something physically different about life with minds versus life without minds. So assume we narrow it down to some biochemical process that every living thing with a mind has. But now what? We still haven't detected the mind. There would still be the mind-body problem simply because the subjective consciousness can experience and have its physical properties. This subjective consciousness is a property in of itself. This makes the mind something entirely different from physical, but a immaterial property of the physical nonetheless. The mind would simply be something directly correlated with what the chemical process does. The mind couldn't escape or have any autonomy. It is said that the mind would be like smoke coming out of a train, or a passenger taking ride in a boat.
×