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Suppose both A and B are moving at 2/3 the speed of light relatively to O. You’d think that A and B would be moving a 4/3 speed the light relatively to each other, wouldn’t you? To those stationary, the moving object would appear slowed down and contracted in length, but it would not appear to travel faster than the speed of light, precisely due to the relative effects in question . If you can travel faster than the speed of light in some reference frame , there is always a different reference frame where this journey goes backwards in time. “So science fiction has long postulated a way to beat the speed of light barrier so the story can move a little more quickly.”

• The faster-than-light ship is moving so fast that it can outrun any light that it emits.
• The geometry of spacetime is definitely tied to causal order through the light cone.
• Seldon / public domain This is an enormously important property in particle physics, as it’s this very process that allows us to detect the elusive neutrino at all.
• This does not violate Einstein’s theory because his theory provides that nothing may move faster than the speed of light in a vacuum because space is nothing.
• In fact, if you have any event that causes a change somewhere else the cause and effect are delayed by a time because of the speed of causality.

This is a very common confusion and it comes about because historically physicists used something called the relativistic mass which does change with speed. No one uses best t shirt printing equipment this today any more, so the best is to just forget about it. The masses of elementary particles are constants of nature. For me we are missing something with respect to time and its passage, not with respect to travel speed. I believe that we could also say that the various options for faster than light or great distance travel is showing us that we are missing something with respect to time.

First and foremost, Dr. H I think you should be proud of the discussions you start in your blogs. I have found the open and honest discussion you illicit to be fascinating, right, wrong or indifferent. You have provide a place where people can come and for the most part have open discussions about a critical and complex topic. “The standard answer is no, and several reasons can be given, one of which is that superluminal signaling would imply the ability to send signals into our causal past, which conflicts with all our experience.” ” supports the Feinberg argumentation that in order to determine the tachyon velocity it is sufficient to measure momentum and energy of tachyons…” “Third, for infinite velocities momentum of tachyons vanishes while their energy remains finite…”

Why Does Time Slow Down As You Approach The Speed Of Light?

There is a growing body of evidence that suggest electromagnetic forces are the driving force for planet, star and galaxy formation. Anthony Peratt’s work at Los Alamos convincingly showed spiral galaxy formation from plasma. More importantly these formations had the necessary velocities so that black holes and dark matter/energy were not required. Okam’s Razor should be considered when comparing electromagnetic versus gravitational theories.

More From The Infinite Universe

Thank you, Dr. Hossenfelder, for taking the time to explain this to us. Correct me if I’m wrong, but I believe your point is that spacetime is curved, and hence in the real world any inertial reference frame is valid only locally, i.e. spacetime is flat only close to the observer. C is the speed of light in a vacuum, and it is the fastest speed that anything can travel through spacetime.

In fact, the far reaches of the Universe are already stretching away faster than its light could ever hope to match. Within conventional physics, in accordance with Albert Einstein’s theories of relativity, there’s no real way to reach or exceed the speed of light, which is something we’d need for any journey measured in light-years. No object can travel faster than the speed of light because as objects travel faster, they get heavier. Therefore, it is only light that can travel at the speed of light – because it has no mass. Pretty much any time light travels through a medium (air, water, glass, etc.) it is traveling below the speed of light .

If you can communicate from point A to point B for any two points A and B that are spacelike separated, then you can communicate from point A to point B to point C, where C is in A’s past light cone. And if you assign a “real time” to every point and are only able to communicate forward in “real time,” this violates relativity. So either relativity is wrong or communicating faster than light is impossible . Or maybe there’s a third possibility, but I’ve failed to grasp it from your explanation.

1) Any measurement of c will yield the same value at any time. But this understanding of a constant c is not able to solve cosmological horizon problem by the assumption of inflation, because the relation of c to space will never change and so the conflict remains. If there are Tachyons AND there is an Interface between Lorentzian Sensibilities and the Superluminal, there is without doubt a very strict Arrow of Time – reversing Superluminal parts with Sub-Luminal parts will not “reverse time”. Only at the shortest distances could there be such an exchange and that would not reverse time but would provide, for ex., a rationale for understanding CP violations. I went back to look at your 2015 blog post, and I think I can see the problem.

Instead, it’s filled with pairs of particles popping in and out of existence. A region in which fewer pairs were allowed to pop in and out than everywhere else would have negative energy density. This is comparable to a journey into the future — even if the time difference between the moving driver and the resting observer is only a billionth of a second. Will we one day be able to build a machine to travel to the past as well as the future? In a guest post for The Conversation, researcher Peter Millington of the School of Physics and Astronomy at the University of Nottingham tried to get to the bottom of some of these questions.

Einstein’s theories say that we cannot increase the speed of the transmission, but scientists say that we can increase the amount of information that is transmitted. If scientists can increase the bandwidth of a transmission then they can send more data every second, especially if they were able to compress the data and decrease errors. Again, this does not mean that messages would travel at the speed of light. However there is hope that while the speed of light is constant and so far unbreakable, there may be a short cut.