tag:blogger.com,1999:blog-22973357.post8400984803686009058..comments2021-05-08T06:12:29.394-04:00Comments on Sabine Hossenfelder: Backreaction: Do we really travel through time with the speed of light?Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comBlogger81125tag:blogger.com,1999:blog-22973357.post-15063144655241643132021-04-09T04:19:22.727-04:002021-04-09T04:19:22.727-04:00In fact right that way the case is in the relativi...In fact right that way the case is in the relativity.<br /><br />You can imagine it so that every orthogonal space dimension can be exchanged with time in turns. We only project the changing continuum of 4d to linearity in 3:1. The choice is ours humans - of course well argumented with our emergent rest frame.Eusahttps://www.blogger.com/profile/14114706429392111062noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-25851042638333306512021-04-08T20:02:53.100-04:002021-04-08T20:02:53.100-04:00"Now, of course there is a difference between..."Now, of course there is a difference between time and space, so that can’t be all there is to space-time. You can move around in space either which way, but you cannot move around in time as you please"<br /><br />IMHO this difference doesn't exist.<br /><br />Since there is no absolute space, there are no immaterial coordinates or stationary "points" in space. There are Plankalkülhttps://www.blogger.com/profile/06436729620905258626noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-27206354243216794962021-01-04T04:53:59.093-05:002021-01-04T04:53:59.093-05:00Makes sense. If you were to move through space-tim...Makes sense. If you were to move through space-time at a speed close to the speed of light then time "stops". You can therefore say you are moving at the same speed as time flies when you're not moving.Catalin Tudorhttps://www.blogger.com/profile/06192244112905762189noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-37207129025611212592020-09-08T15:21:27.181-04:002020-09-08T15:21:27.181-04:00Sabine,
Thanks for an excellent and informative v...Sabine,<br /><br />Thanks for an excellent and informative video! This belated comment is on how minor algebraic manipulations that convert Minkowski spacetime into Euclidean form can make the relationship between time and distance particularly vivid.<br /><br />If the Deltas are implicit your spacetime equation was:<br /><br /><i>s = sqrt( -x^2 -y^2 -z^2 +(ct)^2 )</i><br /><br />Squaring both Terry Bollingerhttps://www.blogger.com/profile/03915136249111338024noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-65448002201550145482020-09-08T10:13:44.100-04:002020-09-08T10:13:44.100-04:00This could be a big experimental result. Measureme...This could be a big experimental result. Measurements of wave function collapse with gamma radiation sources finds no correction that would be attributed to a role for gravitation. This may throw ideas such as Penrose's in doubt. I will post this on a previous blog entry on measuring quantum gravity.<br /><br />https://www.sciencemag.org/news/2020/09/Lawrence Crowellhttps://www.blogger.com/profile/12090839464038445335noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-10885108739646514732020-09-07T12:20:58.437-04:002020-09-07T12:20:58.437-04:00Lawrence,
I'm aware of some optical effects ...Lawrence, <br /><br />I'm aware of some optical effects but it's more than that. If one of those observers was traveling near light speed they would not only view that distance object being closer, if they traveled to it, it would take much less time to reach also. Again, all I've been saying is a simple fact that while they both will measure light speed as 299,792,458 m/s, the Louis Tagliaferrohttps://www.blogger.com/profile/16698865662162457632noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-16758333138761275882020-09-05T17:07:38.718-04:002020-09-05T17:07:38.718-04:00Hi,
One last try.
First to set the record straight...Hi,<br />One last try.<br />First to set the record straight. I'm not saying the video is not clear, not saying anything about the presentation at all, not trying to show i"m smart, not trying to say you are not smart, not trying to say i'm smarter than you, not trying to say you are not thinking, not anything in human relationships. If something i wrote gives this impression, i Ophir Motteshttps://www.blogger.com/profile/08785042355559997727noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-88679545638005581182020-09-04T15:26:45.995-04:002020-09-04T15:26:45.995-04:00Lawrence Crowell says:
“I am not sure of what you ...Lawrence Crowell says:<br />“I am not sure of what you mean by c(object)^2 = c(nominal)^2 - v(motion)^2.”<br /><br />Sorry that this equation is difficult to read. I do not know how to use indices in this text. The summands mean the following:<br /><br />c(object) is the internal oscillation at c in the object. This oscillation is reduced by dilation when the whole object is in motion.<br /><br /antooneohttps://www.blogger.com/profile/12559038212417783694noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-5111452119560768882020-09-04T12:19:06.006-04:002020-09-04T12:19:06.006-04:00I didn't go into this, but there are also opti...I didn't go into this, but there are also optical effects called Terrell rotations. There is, or was, a YouTube video that illustrates this. The voice is a robo-female with a sort of Bengali and British accent. It shows what happens if the speed of light is some ordinary speed and one drives down a road. Then it gets really weird by flying through solid figures.Lawrence Crowellhttps://www.blogger.com/profile/12090839464038445335noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-63076443872363045682020-09-04T12:08:03.041-04:002020-09-04T12:08:03.041-04:00Sabine,
in order to discuss a velocity in time, y...Sabine,<br /><br />in order to discuss a velocity in time, you need that dimension to physically exist "now", including past and future. In this way you may (or may not) be able to define a meter along the axis of time. Assume you can, then my question.<br /><br />Best,<br />J. akidbellehttps://www.blogger.com/profile/12292741599925116131noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-81267814474172112942020-09-04T11:21:16.607-04:002020-09-04T11:21:16.607-04:00Lawrence,
Lawrence said… “Sigh, confusion seems t...Lawrence,<br /><br />Lawrence said… “Sigh, confusion seems to have taken over. Clocks on other frames slow down, but there is also Lorentz contraction of lengths. So while you will observe a clock on some frame moving with a velocity v there is also the contraction of lengths that removes this problem of apparent speeds of light.”<br /><br />That’s exactly what I was saying, c is invariant to howLouis Tagliaferrohttps://www.blogger.com/profile/16698865662162457632noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-46480215286891100292020-09-04T10:20:32.889-04:002020-09-04T10:20:32.889-04:00The explanation in this post seems simple and clea...The explanation in this post seems simple and clear to me. Spacetime has four axes, all with the dimension of distance. Distance along the time-axis of spacetime is c multiplied by the elapsed time. The standard scientific method of verifying theoretical equations with observations confirms this. (The choice of c was not arbitrary.) In high school physics one learns that distance equals rate JimVhttps://www.blogger.com/profile/10198704789965278981noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-68481774298448355102020-09-04T10:06:12.897-04:002020-09-04T10:06:12.897-04:00I can't make sense of your explanation, sorry....I can't make sense of your explanation, sorry. Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-74310787953612599002020-09-04T10:04:31.369-04:002020-09-04T10:04:31.369-04:00Rollo,
Yes, that's correct. As to your questi...Rollo,<br /><br />Yes, that's correct. As to your question. It's a very good question. The brief answer is that the latter statement follows from the former. The empirical component is the observation that photons are (to excellent precision) massless. This does not strictly speaking follow from electromagnetism or special relativity (though it is required by gauge-invariance). <br /><br Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-17858092046353300062020-09-04T08:36:59.462-04:002020-09-04T08:36:59.462-04:00Hi Sabine,
I think your statement can be misleadi...Hi Sabine,<br /><br />I think your statement can be misleading; a better way to state this is that if 4 dimensions exist such that a meter has a meaning along the time axis, then we (like any energy) have the same pace as light along the direction of time. But I see no reason for a factor 1 to 1 between space and time displacement to be mandatory. It could be 1 in time for 2 in space for instanceakidbellehttps://www.blogger.com/profile/12292741599925116131noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-18067571617632694532020-09-04T08:16:29.646-04:002020-09-04T08:16:29.646-04:00Thanks for this, a great video on a great topic :)...Thanks for this, a great video on a great topic :)<br /><br />Aside: one of my personal a-ha moments when trying to get my head round SR as an amateur (reading Susskind’s SR book) was when it was shown that the magnitude of the 4-velocity is always c. So basically (my way of understanding, which is hopefully correct, goes!) everything is always moving at the speed of light in a 4 dimensional Rollohttps://www.blogger.com/profile/00322514700429344549noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-70540549872354396812020-09-04T06:06:44.102-04:002020-09-04T06:06:44.102-04:00(Part 3)
Ok. In the last part of the video it is s...(Part 3)<br />Ok. In the last part of the video it is suggested that we do the following:<br />Measure our time in seconds, let' say we measure 1 second. Calculate what is the distance in spacetime in meters between the two points of 'start time measure' and 'stop time measure'. We get 1 second * 300 million = 300 million meters, or with our new name 1 feet* 300 million = 300 Ophir Motteshttps://www.blogger.com/profile/08785042355559997727noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-61450171998922829632020-09-04T06:04:54.572-04:002020-09-04T06:04:54.572-04:00(Part 2)
We have two objects in our space. One obj...(Part 2)<br />We have two objects in our space. One object explodes, then the second object explodes.<br />What is the distance between the two explosions in spacetime?<br />We cannot do part 3 of the procedure, so we cannot measure this. But we can measure the distance in our space between the two objects, and let's say we do that with a ruler (a line of numbers) with a calibration called Ophir Motteshttps://www.blogger.com/profile/08785042355559997727noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-13925802879947026362020-09-04T05:57:15.906-04:002020-09-04T05:57:15.906-04:00Let me try again. (Part 1)
To measure distance bet...Let me try again. (Part 1)<br />To measure distance between two points you need:<br />1) a line of numbers<br />2) calibrate the line of numbers and give the specific calibration a name (meter, feet, second, david... Whatever name you want. It is an identification)<br />3) place the line of numbers along what you want to measure.<br />4) read the numbers off the line at the two points, and the Ophir Motteshttps://www.blogger.com/profile/08785042355559997727noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-3885872235987933452020-09-04T05:31:28.313-04:002020-09-04T05:31:28.313-04:00Sigh, confusion seems to have taken over. Clocks o...Sigh, confusion seems to have taken over. Clocks on other frames slow down, but there is also Lorentz contraction of lengths. So while you will observe a clock on some frame moving with a velocity v there is also the contraction of lengths that removes this problem of apparent speeds of light.Lawrence Crowellhttps://www.blogger.com/profile/12090839464038445335noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-65131079478128988852020-09-04T00:40:30.922-04:002020-09-04T00:40:30.922-04:00That's correct.That's correct.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-25556210283887177052020-09-03T16:05:18.702-04:002020-09-03T16:05:18.702-04:00Lawrence,
Those atomic clocks in the relativity t...Lawrence,<br /><br />Those atomic clocks in the relativity test showed, when brought back together into same inertial frame that, they recorded time differently. While I know, and I am sure c is invariant for each observer it must also be invariant to each clock’s record of time otherwise the observer’s would not see c as being invariant, c is distance per time. You can’t have the distance value Louis Tagliaferrohttps://www.blogger.com/profile/16698865662162457632noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-7969629209058813452020-09-03T13:37:58.499-04:002020-09-03T13:37:58.499-04:00There is an equivalence between spacial and tempor...There is an equivalence between spacial and temporal distances. An apple isn't an orange, but they have equivalent values of calories, fibre and vitamin C for example. You can convert some of your 'time-speed' into 'space-speed' at a certain date.Gussssshttps://www.blogger.com/profile/01580397952337096758noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-74056926557423761642020-09-03T13:31:44.233-04:002020-09-03T13:31:44.233-04:00A better way to put it is that we travel through s...A better way to put it is that we travel through spacetime at the speed of light, and 𝘰𝘯𝘭𝘺 the speed of light, our speed never varies. In the special case where we are motionless in all space dimensions then that speed is entirely in the direction of time, and conversely this explains why we can never exceed 𝘤 in space, as this is the only speed we ever travel at.Gussssshttps://www.blogger.com/profile/01580397952337096758noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-80675247857976939582020-09-03T13:20:37.821-04:002020-09-03T13:20:37.821-04:00I am not sure of what you mean by c(object)^2 = c(...I am not sure of what you mean by c(object)^2 = c(nominal)^2 - v(motion)^2. The speed of light in flat spacetime is constant. Above I do write something similar with coordinate and proper time.Lawrence Crowellhttps://www.blogger.com/profile/12090839464038445335noreply@blogger.com