Maartenn100

Traveling at speeds close to the speed of light does introduce significant time dilation, meaning that while less time passes for the traveler, more time passes for those who remain behind on Earth. However, this doesn't necessarily mean it's only a one-way trip where "one just flies away and gone." While traveling at relativistic speeds, the astronaut's experienced time (proper time) is much shorter than the time elapsed on Earth. This means that a round trip is possible from the traveler's perspective within their own lifetime. Example Suppose an astronaut travels to a star 10 light-years away at a speed close to c.For the astronaut, due to length contraction and time dilation, the journey might take only a few years each way. However, from Earth's frame of reference, decades might have passed. :The traveler can return to Earth, but they would find that much more time has passed on Earth than they have experienced. and family may have aged significantly or passed away, and society could have changed drastically. Not Just "Gone": The traveler isn't lost or unable to return; they can physically come back. The key issue is the asymmetry in experienced time between the traveler and those on Earth. Practical Considerations: Relativity of Simultaneity: Events that are simultaneous in one frame of reference are not necessarily simultaneous in another moving at a high relative speed.This affects synchronization of time between Earth and the spacecraft. Communication Delays: Even at light speed, messages would take years to travel between distant points, complicating real-time communication. Conclusion: Not Necessarily One-Way: While the social and personal implications are significant due to time dilation, the journey isn't strictly one-way.The traveler has the ability to return, but must be prepared for the changes that have occurred during their absence. Future Possibilities: Advances in technology and understanding of physics might offer solutions to mitigate these issues, such as:Cryogenic Sleep: Extending the life of travelers to better align with Earth's time frame. Warp Drives or Wormholes: Hypothetical methods that could allow for faster-than-light travel without violating relativity. Summary: Traveling at relativistic speeds allows for round trips within the traveler's lifetime, but significant time will have passed on Earth due to time dilation. While this presents emotional and social challenges, it's not accurate to say the traveler is simply "gone." The possibility of return exists, but it comes with the understanding that the world they return to may be vastly different from the one they left.

It is true that accelerating an object with mass to the exact speed of light c would require infinite energy, and that this is physically impossible. However, it is not necessary to reach the speed of light to experience significant relativistic effects such as length contraction and time dilation. Length Contraction: The distance to your destination becomes significantly shorter in your own frame of reference. This makes it possible to bridge enormous cosmic distances within a human lifetime without needing to reach the speed of light. Energy Requirements: While it is true that the energy needed to get closer to the speed of light increases exponentially, this energy remains finite as long as the velocity is below c. The energy E required for acceleration is given by: E = (γ - 1) * m * c^2 where: m is the rest mass of the spacecraft. γ (gamma) is the Lorentz factor, defined as: γ = 1 / √(1 - v² / c²) Although E becomes large at high γ, it is not infinite as long as v < c . Practical Approach: Constant Acceleration: If we maintain a constant acceleration of, for example, 1g (9.81 m/s²), we can reach very high speeds within a reasonable proper time without overburdening the human body. Travel Time to Nearby Stars: To Alpha Centauri (4.37 light-years away): The travel time in proper time (your experienced time) would be only a few years with constant acceleration and deceleration. Technological Advancements: Although our current technology does not yet allow for this, it is theoretically possible that future technologies could provide the necessary energy—through means such as antimatter propulsion, nuclear fusion, or other advanced methods. Conclusion: Theoretical Possibility: According to the theory of special relativity, it is possible to traverse enormous distances in the universe within a finite and practical time span in your own frame of reference, without requiring infinite energy. Practical Challenges: While there are significant technological and energy challenges remaining, this does not exclude the possibility that such journeys could become feasible in the future. In summary, while it is physically impossible to reach the speed of light due to the infinite energy that would be required, it is not necessary to reach c to benefit from the relativistic effects that make interstellar travel within a human lifetime possible. By traveling at speeds close to, but below the speed of light, we can theoretically bridge any distance in the universe thanks to length contraction and time dilation, without the need for infinite energy.

According to Einstein's theory of special relativity, when traveling at speeds close to the speed of light, you experience a significant shortening of distances in the direction of your motion. This phenomenon is known as length contraction. This means that any distance in the universe is reachable as long as we can travel close enough to the speed of light, because as v approaches c, γ\gamma becomes very large, and thus L becomes very small. For an observer who is stationary relative to your motion (an "outsider"), your clock seems to run slower; this is called time dilation. But from your own perspective inside the spaceship, time proceeds normally, and it is the distance to your destination that becomes shorter. This can be expressed using the following formulas from special relativity: L = L₀ / γ Where: Lo is the rest length (the length measured in the reference frame where the object is at rest), γ\gamma (gamma) is the Lorentz factor, defined as: γ = 1 / √(1 - v² / c²) v is the speed of the moving object, c is the speed of light. Time Dilation The dilated time Δt measured by the stationary observer is given by: Δt = γ * Δt₀ Where: Δt₀ is the proper time (the time measured in the reference frame of the moving observer). Explanation For you in the spaceship: The distance to your destination L is smaller than the rest distance L₀ due to length contraction. Time passes normally for you; you don't notice any difference in the flow of time in your own reference frame. For the outsider: Your clock seems to tick slower due to time dilation. The distance between the starting point and the destination remains L₀. There is no length contraction in their reference frame. These effects become significant at speeds that are a substantial fraction of the speed of light. They result from the way space and time are interwoven in the theory of relativity. Conclusion Any distance becomes reachable once you travel close to the speed of light.

Think about it: the brain is nothing different than electricity flowing through wires. The brain is an electricity-producing machine. That's what we are. And electricity flowing through wires produces magnetism. And maybe, magnetism = consciousness.

The brain is nothing more than an electronic device. So, every electronic device with a lot of interconnected wires should be conscious too while switched on. We can use a bunch of steel wool and run electricity through it and we should have recreated a small artificial brain. The question is: how do you ask questions to it.

Time is relative, depending on the opinion of an observer. An observer who went a few times in the neighborhood of a black hole and returned back to Earth has another idea of the age of Earth and the decay rate of these radioisotopes, than an observer who stayed on Earth. Time is relative. No absolute property of the universe in itself. Since Einstein there is no universe with absolute time properties (and absolute space properties).

Is yesterday still here? Does the past exist? Is the future already here? Does the future exist? No, there is only the 'now'. And what is the duration of 'the now'? The 'now' cannot have any duration because otherwise it would have a past and a future, which is not 'the now'. So the duration of the now must be zero. No past, no now (zero) and no future = no time. So time does not exist.

What follows is what I believe to be a simple logical mathematical reasoning that explains why time cannot exist in the 'outside world', but that the experience of time is a property of a consciousness interacting with this 'timeless' outside world. The assumption is that if duration actually existed 'out there', you would have to go back infinitely to get to the beginning. Possibly involving multiverses and so on. You would have an infinite past. Because even if there was nothing in the universe, there would still be a duration. That is my assumption. When you do x "minus infinity", you have the idea that you have moved x infinitely downward, towards an infinitely negative value. To return to x by adding numbers, you would theoretically need to add an infinite amount. With respect to time, this would mean that; When you go back to minus infinity in time and then let time pass to the now, it would take an infinitely long time to reach the now. In other words: the 'now' could never be reached. Because it would take an infinitely long time to reach the now from an infinitely distant past. Therefore, duration cannot be something of the reality 'out there', but duration is something that we experience or measure as a result of the interaction of a consciousness with the reality outside that in itself does not know a sequential order of events in time, as we experience it. As Immanuel Kant formulated it: the passage of time belongs to the phenomena not to the noumena.

The comoving observer. Ok, thanks.

Give me some time. I will try to study first GTR better. Later I will answer when I understand it better.

Psychedelics show that brain activity reduces, the more intense the psychedelic experience. See the research of Robin Carhart Harris of Imperial College London of the brain on psilocybin. (magic mushrooms). see here: Neural correlates of the psychedelic state as determined by fMRI studies with psilocybin | PNAS The remarkable effect was: the more intense the experience, the less brain activity was seen. A negative correlation between consciousness and the amount of brain activity. This, and many other phenomena, confirm the 'filter theory' of consciousness, where at a certain point, we get access to Mind at Large or 'the block universe' or 'the universe as a whole'. This is the unity experience of mystics where there is no time. This correlates with a bad working brain, with no or less oxygen indeed. The more damaged the brain is, the more people experience Mind at Large and 'all events simultaneously'. This is a hypothesis, but this 'no time experience is another piece of the puzzle to see that time is an illusion of a mind connected to a body. Or to an observer in time and space.

Imagine a world without observers. Even you, observing your own body in time are not attached to this body anymore. Everything exists simultaneously (Einstein) in the block universe. We know from NDE-ers who ar not attached to their body anymore that they can confirm that they experience 'everything at once'. They experience no time. A place where everything is accessible in the present. There is no time. Many observers who are not attached to their bodies during a near-death experience can confirm this. They experience the block universe as it is in itself, without them observing it attached to a body in time and space.

In my opinion, what's common in general relativity theory and quantum theory = observers. Einstein talked about observers and in quantum theory 'the observer effect' plays a role. So, to unite both theories, we have to look at the world with observers versus the world without observers. In my opinion: in quantum theory 'everything is in superposition' when there are no observers. In relativity in the block universe: everything happens simultaneously when there are no observers. I think that the difference between a world with observers versus a world without observers is a world where events happen sequentially versus a world where everything happens simultaneously. When the scientist (and all other observers) isn't there, all the steps to execute the experiment are all together existing in spacetime simultaneously. When there is a scientist, this is been observed as sequential order of events through time.

My point is that you can not make statements about the duration since the socalled big bang (the age of the universe), because different observers will disagree on this idea. And even if the differences are small, the fact that there is a difference makes a big difference for in what kind of universe we live. A universe with a relative time where there can be no statements about age or time or a universe with absolute time or space.

But if you now travel close to a black hole for a few months and return to Earth, your perception of the elapsed time since the Big Bang will differ from that of other observers. Thus, your method of reckoning time violates the principle of relativity of time in my opinion.

Indeed: we measure with our clock. You say: 'Most clocks in galaxies run at about the same rate unless you're near a black hole or moving at a significant fraction of c'. The distinction between a universe where time, or age, is relative, and one where the universe's age can be precisely defined, is critical. Even minor discrepancies in time measurements suggest significant differences in our understanding of the universe: one with a definite age versus one without a measurable timescale.

I follow simple logical deduction from true premises: True premise: Space and time are no longer absolute as in the time of Newton. They are relative, since Einstein. Valid logical conclusion: There is no preferred reference frame for space. Supporting (thought) experiments: Observers can be conceived who measure a different space. (a photon, a hypothetical observer close to the speed of light approaching Proxima Centauri). Valid conclusion: Every observation of space is relative. THUS ALSO the observation of expanding space, as an interpretation of the observation of the Doppler effect of light emitted from distant galaxies, by 'expansion of space' moving away from us. True premises, logical reasoning, valid conclusion. And there is not only no preferred reference frame for space where every observation of space is relative, so also the observation of expanding space. There is also no preferred reference frame for time. Therefore, (elapsed) time since the so-called Big Bang is also relative. Different observers with their own clocks will measure a different duration since the Big Bang. So, the so-called age of the universe depends on which clock? Which preference do you give to which reference frame for (elapsed) time since the so-called Big Bang?

Your idea is to 'stick with the math'. The current models of the expanding universe, such as the Friedmann-Lemaître-Robertson-Walker (FLRW) metric, are, as I understand it, solutions to the Einstein field equations that describe the entire universe as a whole. These models assume the cosmological principle, which states that the universe is homogeneous and isotropic on a large scale. This is an unproven assumption that is simply taken for granted. One cannot oversee the entire cosmos and confirm this cosmologicle principle. Within this unproven framework, observations of the expansion of space are seen as consistent for all observers, despite the relativity of individual time and space measurements. New observations challenge the (unproven claim of) cosmological principle: Newly discovered cosmic megastructure challenges theories of the universe | Space | The Guardian So, the scientists do not 'stick with the math' either.

If there is simultaneity of all events in the block universe/spacetime, then there is no sequential order of events through time in the block universe. Then there is no timeduration in the block universe/spacetime. Then there is no time. Only observers measure timeduration. And they disagree.

The 4D spacetime can be conceptualized as a "block universe," an idea that stems from Einstein's theory of general relativity. In this model, the universe is viewed as a four-dimensional spatial structure, where time is akin to the spatial dimensions, and all moments in time—past, present, and future—exist simultaneously. It's this spatial Block universe that can only be conceptualised. In the block universe, the future is as 'fixed' as the past; both are already "written" and exist within the four-dimensional space. This concept is abstract and can be difficult to grasp since our everyday experience of time is sequential—we experience time as flowing from the past to the future. Visualizing the block universe as a geometric figuren, is an abstract concept in our minds. More real then the relativistic observations of time and space.

My point is that the universe without observers has no such properties like relative time and space distances.

4D-spacetime is very real. Even more 'real' then our relative measurements of space and time. You can not measure spacetime distances. You need to calculatie them. What you measure are relative spacedistances and time. Spacetimemetriek is calculated. Not observed.

But I start from the principle of relativity that since Einstein there is no absolute time and space anymore like according to the Newtonian worldview. Space is also relative. (and time) There is no preferred reference frame for space. So, the observation of 'space-expansion', seen from the point of view of an observer in a spaceship going at 0.99c of the speed of light towards Proxima Centauri, slowing down again, is 'the relativity of space' at work. This observer will see a so-called 'space-expansion' of the earlier contracted space/length in front of his spaceship, slowing down again. And this space-expansion is of the same kind of every other space-expansion we observe. If space is relative, everything we observe about space is relative and depending on observers. There are observers who 'see' zero space in the universe. Like a foton. So, if you say: 'space is expanding' (the universe is expanding), in my opinion: it's your particular ruler that is expanding, given your clock and given your position in spacetime. The metriek you use to calculate spacetimecoordinates is something conceptual. 4D-spacetime cannot be directly observed. The block universe is a conceptualised idea. More 'real' then our relativistic observations of space (and time), but a concept.

Thank you. But do you agree with the following statement: we can disagree on the measured distances (space) But we always agree on the calculated spacetimedistances. Spacetimedistances are calculated or deduced. Distances in space can be measured with lasers for example. The measured spaces are always relative, but the deduced (not observable) spacetimedistances are absoluut. So: every observed expansion of space is a relativistic observation of space. We cannot observe spacetime. (the universe in itself) We can only deduce it. Is that true?

I don't want to change the science of ART. I'm not capable of doing that! Only the interpretation to explain that science is different. The observed expansion is, for me, an observed expansion of our private ruler and not of the metric of the universe itself. Because when you want to know properties of the universe by itself, you have to look at an object that has the same properties for all observers: a photon in vacuum. Well, take that as a reference frame to posit things about the universe itself, without observers. You want to know something about space and time about the universe itself, independent of observers. Ask a photon in vacuum. A photon has absolute properties (not relative) for all observers. It can tell us something about the universe that is the same for all observers. The mathematics and science for it already exist. So, this is just a different interpretation of the existing scientific truths. Nothing changes about the science, but something changes about the interpretation of expanding space and what the universe without observers means by looking at a photon in vacuum. This is a matter of interpretation, not of science, because the science and math are the same: If you want to find something that all observers agree on, it's the properties of a photon in a vacuum. And as strange as it may sound: according to a photon, the actual age of the universe, and thus the real time in the universe, is ZERO. t' = (t - vx/c^2) / sqrt(1 - v^2/c^2) = 0 Time, just like space, is a property of observation. Not a property of the universe itself.