Does the Past Still Exist?

Albert Einstein taught us that space and time belong together to a common entity: space-time. This means that time becomes a dimension, similar to space, and has profound consequences for the nature of time. Most importantly it leads to what has been called the block universe, a universe in which all moments of time exist the same way together. The future, the present, and the past are the same, it is just our perception that suggests otherwise.

0:00 Intro
00:58 Space-time
02:09 Space-time diagrams
03:40 Special Relativity
05:05 The Relativity of Simultaneity
10:36 The Block Universe
12:46 The if's and but's
14:50 Sponsor Message

[Master_Therion]

I've been patiently waiting for Sabine to make a video on this topic. It's about time.

[finaleoftheseason]

It's like a book or a movie on your computer. The beginning and the end is already there. But the people in it don't have a clue. Just like us. Since we're stuck in the 3rd dimension, we perceive things bound to time. To get out of it, we need a different form of body with a different set of new senses. Which we couldn't get until we die. So, "Does the past 'still' exists?" is like asking "Is Dumbledore 'still' alive?" On what page? Because he lives and he dies, everything all at once in the book.

[beanogas]

I used to think as a child that...if anything has ever existed in time, it must still be there somewhere

[kurisutofusan]

This is the first video I see on this channel. This is very refreshing to have explanations without all the usual background music, hyperactive ton of speech, or lots of graphics moving around!
The calm tone of the video is very good for learning!

[Gliese]

The past haunts me every day, whether it still exists or not.

[johnkaeden]

You’re the best kind of teacher. Your going over really high brow stuff, but you make it interesting and easy to understand. That and you’re crushing it with the jokes! Great work!

[Chrisamusic]

YES it does! I'm sitting here in the quiet English countryside, on a dark winter's night, looking high above me, into a black sky full of stars; many of which are now dead – but because of my unfathomably distant vantage point, are still up there shining, still ‘alive’. Could it then follow that an alien being sat on the other side of the galaxy, looking our way through some kind of ‘advanced super telescope’, could maybe – just maybe, see my late mum and dad, meeting for the very first time on that dizzy late summer's evening they used to tell me about?
Believe it; somewhere, everyone and everything is still alive. ❤️

[christinablacken]

This video made me realize how often we are watching the past. All YouTube videos we watch in the present were made in some recent or distant past and can be played actively as if they are now in the present. All media and entertainment that’s recorded is that way. I think that’s why stories play such an important role in human development - story is time travel.

[HauntedOne]

that snap from the exorcist @3:35 will keep me awake now for the night

[kylebeetham]

If the past doesn’t exist then why is my wife still mad at me for leaving her car lights on 12 years ago?

[SuperWingram]

I do love the dry humor woven into the ‘story telling’ and then referred to again randomly…a stand up comic schtick that amazingly turns a physics lecture into a conversation between friends. Brilliant.

[nelsonclub]

This was posted about a year ago and its still here. So yes.

[jazjobse]

Love hearing your expounding the theories Sabine

[richclarke]

Also notice that our memories can have differences in this manner. My memories of 50 years ago ( I am 80 ) are in a distant past...but the things I did, that I wish I hadn't, such as being rude as a teenager to someone, and we never forget, is as if it was yesterday.

[jimihendrix]

Not exactly sure about what you said but i did enjoy the way you said it.

[JohnSmith-ufyn]

Time is… truly a paradox.. I keep finding myself coming back to this video.. why…?

[adrianamatlack]

OMG this is a truly incredible video, best one I have seen on the subject. This really is an incredibly good lecture. I have been studying this subject for many years, back then most of what I worked with was in Physical Review D and books. Some great books out there got me interested in physics and math, but I am very impressed by this video and the deep subjects you talk about. I was a math physics major, though the truth is that most of these fascinating concepts can be understood through thought alone.
The math is certainly interesting. I had to see how it worked. The Tipler cylinder was my first interest, in the math model it is infinite in length so it does not collapse into a black hole. Anyway we know that time like coordinate becomes spacelike and spacelike becomes timelike, but I had to see the math.

I used to talk to Tipler, and Gott on the phone way back, then later I got into Caltech though I did not go. In any case I study this stuff for fun, and this video is magnificent. BRAVO.

[th_CAV_Trooper]

The information earned a thumbs up. Sabine's sense of humor earned a subscription. Sharing this with my software dev buddies.

[qwertycarletous]

Thanks, explains psychology too. I've seen it before

[Thomas-gk]

Every side of Dr. Sabine´s personality is marvolous.