# Gold price at near speed of light **URL:** \ **Category:** Factual Questions\ **Created:** [November 14, 2018, 2:32pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502 "2018-11-14T14:32:09Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [November 14, 2018, 4:50pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/21 "2018-11-14T16:50:13Z")
> [@Slash1972](#): > > If mass doesn’t increase, what is it that prevents one from approaching the speed of light then? The Lorentz term which impacts time, length, and the energy required for acceleration. This is known as γ or gamma. > **[Lorentz factor](https://en.wikipedia.org/wiki/Lorentz_factor)** > > The Lorentz factor or Lorentz term (also known as the gamma factor) is a quantity that expresses how much the measurements of time, length, and other physical properties change for an object while that object is moving. The expression appears in several equations in special relativity, and it arises in derivations of the Lorentz transformations. The name originates from its earlier appearance in Lorentzian electrodynamics – named after the Dutch physicist Hendrik Lorentz. > It is generally denoted... ---
**Author:** ![Great\_Antibob](https://avatars.discourse-cdn.com/v4/letter/g/e47c2d/32.png) [@Great\_Antibob](https://boards.straightdope.com/u/Great_Antibob)\ **Post date:** [November 14, 2018, 4:50pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/22 "2018-11-14T16:50:21Z")
> [@Slash1972](#): > > If mass doesn’t increase, what is it that prevents one from approaching the speed of light then? As above, it’s better, equation wise, to discuss momentum and energy rather than mass. The energy requirement increases without bound the closer you want to get to c. That’s one of the things about ‘tachyons’ that’s kind of interesting. If a faster than light particle exists, it could never slow down to light speed, either, for the same reason of an infinite energy requirement. ETA: In ‘conventional’ Newtonian physics, momentum can be written as m_v and kinetic energy is 0.5_m_v_v. But those go out the window at relativistic speeds unless you let ‘m’ increase to some sort of ‘relativistic mass’. So the idea of a relativistic mass is a not-good way to reconcile how we have taught ourselves things work in a Newtonian world with what we know at relativistic scales. ---
**Author:** ![Slash1972](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/slash1972/32/6461_2.png) [@Slash1972](https://boards.straightdope.com/u/Slash1972)\ **Post date:** [November 14, 2018, 4:53pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/23 "2018-11-14T16:53:01Z")
> [@rat\_avatar](#): > > The Lorentz term which impacts time, length, and the energy required for acceleration. > > This is known as γ or gamma. But that’s just a number in an equation. What are the real-world effects that would hinder a ship approaching the speed of light? “Mass increases” seemed pretty understandable. If I am in a ship, who’s engine is capable of accelerating it 1 m per s per s, as I notice my speed increasing, what happens? ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [November 14, 2018, 4:55pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/24 "2018-11-14T16:55:16Z")
I should add that E= mc^2 is a special case. If you consider that Einstein was talking about _rest mass_ and consider the longer form of: E^2 = (mc^2)^2 + (pc)^2 You will see the momentum component in _p_ As momentum increases the E or energy increases. It is the “(pc)^2” portion that causes you problems. ---
**Author:** ![Great\_Antibob](https://avatars.discourse-cdn.com/v4/letter/g/e47c2d/32.png) [@Great\_Antibob](https://boards.straightdope.com/u/Great_Antibob)\ **Post date:** [November 14, 2018, 4:56pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/25 "2018-11-14T16:56:55Z")
> [@Slash1972](#): > > If I am in a ship, who’s engine is capable of accelerating it 1 m per s per s, as I notice my speed increasing, what happens? You notice that maintaining that 1m per s per s requires more and more thrust from your engine as you go faster. And that eventually, it becomes impossible to maintain, even with infinite energy and that acceleration gradually gets lower and lower and you need more and more thrust just to eke out an infinitesimally small bit of additional speed. ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [November 14, 2018, 4:59pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/26 "2018-11-14T16:59:33Z")
Here is a minutephysics video which will probably help out with this intuition using simple math. [![](https://img.youtube.com/vi/NnMIhxWRGNw/maxresdefault.jpg "E=mc² is Incomplete") ](https://www.youtube.com/watch?v=NnMIhxWRGNw) ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [November 14, 2018, 5:13pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/27 "2018-11-14T17:13:58Z")
> [@Slash1972](#): > > But that’s just a number in an equation. What are the real-world effects that would hinder a ship approaching the speed of light? “Mass increases” seemed pretty understandable. > > If I am in a ship, who’s engine is capable of accelerating it 1 m per s per s, as I notice my speed increasing, what happens? The universe around you changes. Remember everything is relative. It’s in the name of the theory. As as your speed increases, the universe around you slows down. If you’ve somehow managed to invent an engine that will just keep accelerating you forever, as your speed increases the universe around you slows down sufficiently to make it take forever to reach light speed. The best argument against relativistic mass at a more intuitive level, at least to me, is that it only works nicely for energy and momentum. If you try to apply it to **F** = m **a** you will have to divide it into transverse and longitudinal mass. Only forces working perpendicular to the direction of motion give behavior according to the same relativistic mass concept as energy and momentum. In the direction parallel to travel you need to multiply by the cube of gamma to get the longitudinal mass instead. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [November 14, 2018, 5:15pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/28 "2018-11-14T17:15:15Z")
> [@Great\_Antibob](#): > > You notice that maintaining that 1m per s per s requires more and more thrust from your engine as you go faster. And that eventually, it becomes impossible to maintain, even with infinite energy and that acceleration gradually gets lower and lower and you need more and more thrust just to eke out an infinitesimally small bit of additional speed. Only if you make the calculations for an external reference frame. In your own reference frame the energy requirements are the same. ---
**Author:** ![Slash1972](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/slash1972/32/6461_2.png) [@Slash1972](https://boards.straightdope.com/u/Slash1972)\ **Post date:** [November 14, 2018, 5:15pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/29 "2018-11-14T17:15:48Z")
> [@Great\_Antibob](#): > > You notice that maintaining that 1m per s per s requires more and more thrust from your engine as you go faster. And that eventually, it becomes impossible to maintain, even with infinite energy and that acceleration gradually gets lower and lower and you need more and more thrust just to eke out an infinitesimally small bit of additional speed. Ok. But what has happened to you and your ship that causes the same amount of force to no longer provide the same amount of acceleration? ---
**Author:** ![Slash1972](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/slash1972/32/6461_2.png) [@Slash1972](https://boards.straightdope.com/u/Slash1972)\ **Post date:** [November 14, 2018, 5:17pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/30 "2018-11-14T17:17:39Z")
> [@naita](#): > > Only if you make the calculations for an external reference frame. In your own reference frame the energy requirements are the same. This seems like you are saying that it doesn’t take more energy to keep accelerating at 1 m per s per s. Is that what you are saying? ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [November 14, 2018, 5:17pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/31 "2018-11-14T17:17:50Z")
That is a good point, remember that a photon simply does not experience time at all. For a photon being emitted and absorbed is a single event. As a photon doesn’t even experience time how would you even calculate velocity as no time passes? Time as a dimension is something that is experienced by us massive, slower than light objects. ---
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [November 14, 2018, 5:46pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/32 "2018-11-14T17:46:21Z")
> [@virtually\_yours](#): > > you can look at it how you want, but isn’t the dollar is based on gold locked away in fort Knox etc … ? You’re thinking of the [Gold Standard](https://en.wikipedia.org/wiki/Gold_standard). The USA abandoned it in [1933](https://www.history.com/this-day-in-history/fdr-takes-united-states-off-gold-standard). ---
**Author:** ![Little\_Nemo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/little_nemo/32/3120_2.png) [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)\ **Post date:** [November 14, 2018, 6:06pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/33 "2018-11-14T18:06:04Z")
Keep in mind the increasing amount of energy you’ll need as your payload approaches light speed. The increased value of your gold holdings will be cancelled out by your higher utilities bill. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [November 14, 2018, 6:22pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/34 "2018-11-14T18:22:14Z")
> [@Slash1972](#): > > Ok. But what has happened to you and your ship that causes the same amount of force to no longer provide the same amount of acceleration? If you are in a rocket and accelerating constantly, nothing causes the same amount of force to no longer provide the same amount of acceleration. Until you run out of fuel, which is why there are not yet five-day cruises to Saturn on offer. But, assuming you have enough magic antimatter or whatever to keep it up, you will soon enough find yourself in the Andromeda Galaxy and beyond; at the same time, an observer where you started out never sees you exceed the speed of light. In short, nothing is preventing you, it is all a matter of changing coordinates. Your cargo of gold does not increase in mass either, as has been explained. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [November 14, 2018, 6:28pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/35 "2018-11-14T18:28:26Z")
> [@Slash1972](#): > > This seems like you are saying that it doesn’t take more energy to keep accelerating at 1 m per s per s. > > Is that what you are saying? From the reference frame of the space ship doing the acceleration, yes, I believe that is the case. Otherwise speed is no longer relative. ---
**Author:** ![Slash1972](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/slash1972/32/6461_2.png) [@Slash1972](https://boards.straightdope.com/u/Slash1972)\ **Post date:** [November 14, 2018, 6:31pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/36 "2018-11-14T18:31:31Z")
> [@DPRK](#): > > If you are in a rocket and accelerating constantly, nothing causes the same amount of force to no longer provide the same amount of acceleration. Until you run out of fuel, which is why there are not yet five-day cruises to Saturn on offer. But, assuming you have enough magic antimatter or whatever to keep it up, you will soon enough find yourself in the Andromeda Galaxy and beyond; at the same time, an observer where you started out never sees you exceed the speed of light. In short, nothing is preventing you, it is all a matter of changing coordinates. But I wasn’t asking about an observer. I was asking about what happens in my ship as I am measuring my speed. As the speed I calculate gets closer to light speed, what happens? When the speed clicks over the SOL, and I say “Hey, we are going faster than light”, does someone say “No we are not, because the math on this paper says we can’t?” ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [November 14, 2018, 6:32pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/37 "2018-11-14T18:32:10Z")
Consider this - a spaceship approaches earth at 0.9c - as it gets near, its path is deflected due to the gravitational effect of the earth. However, the person on the spaceship sees it differently - to them, time is slower and the distance they are travelling toward earth appears shorter - as a result, the deflection due to earth’s gravity appears to be a greater angle. The only explanation for them is that the effect of the earth deflecting their path is due to a much higher mass - i.e. the earth appears on the spaceship to have the effect of a much higher mass. ---
**Author:** ![Great\_Antibob](https://avatars.discourse-cdn.com/v4/letter/g/e47c2d/32.png) [@Great\_Antibob](https://boards.straightdope.com/u/Great_Antibob)\ **Post date:** [November 14, 2018, 6:36pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/38 "2018-11-14T18:36:16Z")
> [@naita](#): > > Only if you make the calculations for an external reference frame. In your own reference frame the energy requirements are the same. Only for inertial frames of reference, for which there is no favored frame. During acceleration, the ship is in a non-inertial frame of reference, and some frames are better than others. The alternative is you see the earth (or whatever you are leaving behind) accelerating to beyond light speed behind you, which is not possible. There has to come a point when you see that the exertions of your engines no longer produce the same additional velocity for the same energy expenditure. It is simply impossible to continuously accelerate at 1 m/s/s ad infinitum (assuming the energy was available, anyway). Otherwise, after 300 million seconds, you would observe the earth falling behind faster than the speed of light, which violates our known understanding of the universe. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [November 14, 2018, 6:40pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/39 "2018-11-14T18:40:17Z")
Am I the only one who thinks that this guy is a wind-up merchant? This is the kind of discussion we used to have when I was a teenager. ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [November 14, 2018, 7:03pm UTC](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502/40 "2018-11-14T19:03:05Z")
> [@Slash1972](#): > > But I wasn’t asking about an observer. I was asking about what happens in my ship as I am measuring my speed. As the speed I calculate gets closer to light speed, what happens? When the speed clicks over the SOL, and I say “Hey, we are going faster than light”, does someone say “No we are not, because the math on this paper says we can’t?” Faster compared to what? You can apply the same force, which will locally appear like you are accelerating but as you do your clock ticks slower and slower and slower compared to an initially co-moving observer. To an initially co-moving frame, and compared to from your accelerating viewpoint to that same initially co-moving frame you will never reach the speed of light. Speed is meaningless without another reference point and it will be very challenging to try and convey these effects with our intuitive assumptions. Ignoring other matter it will still feel like you are being “accelerated” but at some point what still seems like an arbitrary segment of popper time or your local time will be so long in the initial co-moving frames time that you will exceed the heat death of the universe. This proper acceleration is a measurable acceleration with an accelerometer, but the assumptions our minds try and make is to translate a four-dimensional motion into a three-dimensional motion that we have an intuitive understanding of. When you get away from our slow speeds where our intuitions work our assumptions start to break down. We simply want to use coordinate acceleration in our minds and that breaks down under GR as the universal internal frame assumption that is used in SR does not exist. You can only use proper time, or the local clock time as coordinate time (inertial frame) simply does not hold. Using Four-acceleration, as the proper time follows the world line there is no paradox here. The problem arises from our human mind’s belief that there is some universal clock but remember that the spacetime interval is the only invariant property in GR once you move past very local and slow interactions. The spacing between events and even the ordering of events is not invariant across observers. The sequence of events, timing of events and order of events is not universal and only causality is preserved. Note this is an oversimplification and built with bad analogies. [Previous page](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502.md?page=1) [Next page](https://boards.straightdope.com/t/gold-price-at-near-speed-of-light/824502.md?page=3)