Q: If a photon doesn’t experience time, then how can it travel?

Physicist: It’s a little surprising this hasn’t been a post yet.

In order to move from one place to another always takes a little time, no matter how fast you’re traveling.  But “time slows down close to the speed of light”, and indeed at the speed of light no time passes at all.  So how can light get from one place to another?  The short, unenlightening, somewhat irked answer is: look who’s asking.

Time genuinely doesn’t pass from the “perspective” of a photon but, like everything in relativity, the situation isn’t as simple as photons “being in stasis” until they get where they’re going.  Whenever there’s a “time effect” there’s a “distance effect” as well, and in this case we find that infinite time dilation (no time for photons) goes hand in hand with infinite length contraction (there’s no distance to the destination).

At the speed of light there's no time to cover any distance, but there's also no distance to cover.

At the speed of light there’s no time to cover any distance, but there’s also no distance to cover.  Left: regular, sub-light-speed movement.  Right: “movement” at light speed.

The name “relativity” (as in “theory of…”) comes from the central tenet of relativity, that time, distance, velocity, even the order of events (sometimes) are relative.  This takes a few moments of consideration; but when you say that something’s moving, what you really mean is that it’s moving with respect to you.

Everything has its own “coordinate frame”.  Your coordinate frame is how you define where things are.  If you’re on a train, plane, rickshaw, or whatever, and you have something on the seat next to you, you’d say that (in your coordinate frame) that object is stationary.  In your own coordinate frame you’re never moving at all.

How zen is that?

Everything is stationary from its own perspective.  Only other things move.

Everything is stationary from its own perspective.  Movement is something other things do.  When you describe the movement of those other things it’s always in terms of your notion of space and time coordinates.

The last coordinate to consider is time, which is just whatever your clock reads.  One of the very big things that came out of Einstein’s original paper on special relativity is that not only will different perspectives disagree on where things are, and how fast they’re moving, different perspectives will also disagree on what time things happen and even how fast time is passing (following some very fixed rules).

When an object moves past you, you define its velocity by looking at how much of your distance it covers, according to your clock, and this (finally) is the answer to the question.  The movement of a photon (or anything else) is defined entirely from the point of view of anything other than the photon.

One of the terribly clever things about relativity is that we can not only talk about how fast other things are moving through our notion of space, but also “how fast” they’re moving through our notion of time (how fast is their clock ticking compared to mine).

 

The meditating monk picture is from here.

This entry was posted in -- By the Physicist, Relativity. Bookmark the permalink.

364 Responses to Q: If a photon doesn’t experience time, then how can it travel?

  1. Stephen Cox and others, this thread has led to all kinds of possibilities to me including this one – Quarks are Waves! This is high speculation by a sci-fi writer, but if true!!!!
    Comments welcome.
    https://musea.wordpress.com/2020/04/28/quarks-as-waves/

  2. This has opened so many doors! For example:
    So instead of a ZOO OF PARTICLES, we are looking at a ZOO OF DIFFERENT WAVES, that combine, transform, or decay! Here is more speculation

    WHY CHARGE OF POSITIVE AND NEGATIVE EXACTLY THE SAME, plus some other questions and ideas, from a sci fi writer .

    Why charge of positive and negative exactly the same? They have to be because the waves of each are exactly the reverse in destructive interference. That is what I suggest charge is – exact destructive interference of waves.

    “It might be that the exact matching of the electric charge is actually another sign that there are deeper components underlying these particles or perhaps these two types of particles are actually two sides of the same coin…” Cham and Whiteson

    Fact: The total charge of the universe is zero. Number of surviving electrons matches the number of surviving protons.

    QUARKS MAY BE 3 CRESTS AND TROUGHS OF WAVES.

    My Diagram suggested that –
    Quarks are crests and troughs of waves that make a proton or neutron.

    Proton as two crests and one trough wave =
    3 quarks = +2/3 -1/3 +2/3

    Neutron as two troughs and one crest wave =
    3 quarks = -1/3 +2/3 -1/3

    This suggest that if quarks are parts of a single wave, we may not need the idea of quarks
    This suggests that, like electrons; protons and neutrons are in orbitals.
    This suggests that the neutron orbital is SLIGHTLY smaller than the proton.

    THE OLD IDEA THAT PROTONS AND NEUTRONS ARE STATIONARY PARTICLES MAY BE WRONG.

    My Diagram suggests that protons and neutrons are NOT stationary particles, but active wave/particles in orbitals that are MUCH smaller than the electron orbitals around the nucleus.

    Then too, these waves/particles that make up the proton and neutron, must have incredible superposition, and destructive interference – not to mention momentum. – that would be a massive STRONG force between them. Could that be a clue to the strong force?

    Fact: Atoms, electrons, protons and neutrons do behave like particles. … Atoms, electrons, protons, and neutrons also behave like waves! In other words, matter is just like light in that it has both wave-like and particle-like properties.

    Fact: Superposition does not mean that an electron may have one momentum or another – it means that the electron literally has all the momenta at once.

    PIONS AND KAONS MAY BE WAVES TOO.

    We now think pions and kaons are two quarks.
    What if they are extremely small waves such that the wave has one crest and one trough – each representing one quark.

    ELECTRON AND PROTON MAY BE THE SAME SIZE

    Both the quark and the electron are virtually the same size at (10)-16 cm.
    But I suggest that the 3 quarks (up and down quarks) are really just the crests and troughs of extremely small orbitals.

    THEN, that suggests the electron and proton may be virtually the same size.
    But how can that be?

    Fact
    The 3 quarks of a Proton = 1% of the mass of the proton.
    The binding energy of a proton = 99% of the mass of the proton.

    Quote:
    Particles in current theory are actually indivisible points in space. In theory they take up zero volume and are located at one infinitesimal location in 3D space. There’s actually no size to them at all. Even the mass we assign to basic particles like the quark or electron isn’t really stuff either. In fact there is no such thing as stuff. Cham and Whiteson.

    Summary: So instead of a zoo of strange particles, we are looking at different waves that combine or ‘decay’

  3. This post has opened so many doors. Here are ideas on waves and existence.
    The enclosed video from the 2-3 minute mark, suggests that on the quantum level an electron wave represents existence . When the wave is at the anti nodes or crests, it is most likely to be in existence. When the wave is at the nodes, it is not likely to exist at all!!!!

    So if Dr. Hoang is correct, then on the quantum level, the electron wave/particle comes in and out of existence during parts of the wave!

    What if I took this idea further.
    Would that mean that a proton wave acts the same way as the electron wave?

    Would that mean that the existence of not only fundamental wave/particles come into and out of existence, but all quantum particles do as well?

    Would that mean that when any two waves experience constructive interference such that each wave is then enhanced in it’s crests, then does that mean their existence is stronger.

    Would that mean that when any two waves experience destructive interference where the waves reduce the crests to a more ===== form, then does that mean their existence is much weaker or that they are non existent?
    Further is this a clue to how mass comes into existence?
    https://youtu.be/e-xsKfZ7BOA

  4. So why does a free neutron take 11 minutes to decay, and protons are virtually immortal? They are both made of 3 quarks.
    More ideas unleashed for this single thread!

  5. Error: Unable to create directory uploads/2024/03. Is its parent directory writable by the server? The Physicist says:

    @Tom Hendricks
    A neutron has a little more mass than the total mass/energy of a proton, electron, their accompanying EM fields, and a neutrino (almost all of that is the mass of the proton). So a neutron can decay into a proton and not the other way around for the same reason that rocks roll downhill but not up; it releases energy and increases entropy.

  6. Yes you are right but you also are skirting how weird it is if you are right.
    Now tackle these tough questions about quarks as a follow up:
    QUARKS DO NOT MAKE SENSE – or the 3rd quark is REALLY weird.
    Proton = 2 up , 1 down quarks. Neutron = 2 down, 1 up quarks.
    So the difference between the two is the 3rd quark.

    Both have one up and one down.

    That leaves the difference between the proton and neutron as the 3rd quark.
    So difference between a proton and neutron is due to whether the 3rd quark is up as in a proton, or down as in a neutron.

    So, if that’s true then:
    The third quark determines two things:

    If it has an up quark – proton, then the particle is immortal.
    If it has a down quark – neutron, then the particle decays in 10 minutes. EXPLAIN

    If it has an up quark – a proton, then the particle has less mass then the neutron.
    If it has a down quark – a neutron, then the particle has .1% more mass than the proton.
    So the down quark weighs .1% more than the up quark. EXPLAIN

  7. Error: Unable to create directory uploads/2024/03. Is its parent directory writable by the server? The Physicist says:

    @Tom Hendricks
    The properties of a collection of particles is rarely the sum of its parts. For example, neon is a completely non-reactive gas but if you add one more proton to the nucleus it becomes sodium, an extremely reactive metal. Incidentally, the total mass of that new sodium atom is less than the sum of the masses of the neon atom and proton. The mass of a collection of bound particles is the mass of the individual particles plus whatever energy is associated with the group.
    The is especially true of quarks. The up and down quarks have masses of just a few MeV/c2 while a neutrons and protons have masses close to a thousand MeV/c2.

  8. I think we have to agree something is missing here. Perhaps the idea of quarks is at best incomplete!

  9. May I add this too. If it has an up quark, then that magic third quark also determines half of the electromagnetic force in the universe. And it in no way is like the electron, the other half, except in being an opposite charge. Explain how that makes sense.

  10. Here is more to my first post. I’ve added 5 more points at the end, to the discussion.
    QUARKS DO NOT MAKE SENSE – or the 3rd quark is REALLY weird.
    Proton = 2 up , 1 down quarks. Neutron = 2 down, 1 up quarks.
    So the difference between the two is the 3rd quark.

    Both the proton and neutron, have one up and one down quark.

    That leaves the difference between the proton and neutron as the 3rd quark.
    So difference between a proton and neutron is due to whether the 3rd quark is up as in a proton, or down as in a neutron.

    So, if that’s true then:
    The third quark determines these things:

    If it has an up quark – proton, then the particle is immortal.
    If it has a down quark – neutron, then the particle decays in 10 minutes. EXPLAIN

    If it has an up quark – a proton, then the particle has less mass then the neutron.
    If it has a down quark – a neutron, then the particle has .1% more mass than the proton.
    So the down quark weighs .1% more than the up quark. EXPLAIN

    Quarks have no measurable physical extension, and seem to exist at points. Yet that single point does all this and more. EXPLAIN

    The proton has an up quark, and that magic third quark also determines half of the electromagnetic force in the universe. And it in no way is like the electron, the other half, except in being an opposite charge.

    When three quarks team up only a small part of the proton’s mass comes from the masses of the quarks. Most is binding energy. So that third quark has virtually no mass but can do all these magic things. EXPLAIN.

    Quarks interact strongly and link in twos or threes to make particles such as pions, protons, and neutrons. Yet the other half of the charge world, electrons, does none of these things. EXPLAIN

    Physics is a science of pairs. For every particle there is an anti-particle. Virtual particles come in pairs. Spin, waves destructive and constructive interference, etc. In these cases the pairs are virtually identical and or mirror images of each other. So why would electromagnetic charge have electrons and protons so different from each other, and in no way seem built on exact opposites, or mirror image opposites. EXPLAIN!

  11. Pingback: Angel Xenobiology – Barbourian Meditations

  12. Nytowl223 says:

    @Tom Hendricks you have continued to *demand* this physicist answer your questions, even though when he did, you accused him of deliberately omitting something you demanded was more important to explain! Why would anyone continue to interact with someone who is not only demanding but also belligerent to them when they do respond to you?

    No one in their right mind would do that. No one at all would care for being abused when trying to be polite and answering your queries. Perhaps next time you try to be more polite and thankful for an expert’s time and trouble of answering you at all. It’s certainly not their job to do so. One would think you’d be more thankful than hateful when such a person shares their time and expertise with you.

  13. lenbogov says:

    @nytowl223
    He’s just excited about the topic. He wasn’t accusing anyone of anything when he said “we can agree something is missing here”. He meant something is missing from the theory or from our understanding (I’m not saying he’s correct). He didn’t do anything wrong.

  14. Time has speed limits that goes from zero to approaching the speed of light. That means that TIME AND THE SPEED OF LIGHT ARE TWO DIFFERENT AND SEPARATE ENTITIES, which in turn opens up a modern door into physics. This suggests 2 Universes and a different paradigm.

Leave a Reply

Your email address will not be published.