Newsflash: Gravity is Now a Little Weaker; Mass of Proton a Bit Smaller

By Veronique Greenwood | July 22, 2011 1:25 pm

Whip out that red pen and make just a few…little…tweaks…

The physical world should feel a little more comfy now: Gravity is a little bit less than it was last Thursday. And the electromagnetic force? A smidge stronger.

Every four years, the National Institute of Standards and Technology posts internationally determined adjustments to the official values of such natural constants to reflect more accurate measurements made possible by advancing technology. This week, in the latest update, the radius of a proton, the speed of light, the Planck constant, and many, many others have received facelifts that will decrease uncertainty in physics measurements. But this update will also affect units much closer to home: In October, the General Conference on Weights and Measures will vote on a measure to base the definition of a kilogram on the values of such natural constants, instead of the 130-year-old slug of platinum and iridium that currently holds the title.

For the time being, the current upgrade will likely trickle down to we armchair physicists once Google Calculator, the search giant’s handy-dandy constant provider, starts using the new numbers. Judging from its current value for the Planck constant, it’s still working from the 2006 data.

Image credit: Mohr,Talbott/NIST

CATEGORIZED UNDER: Physics & Math, Technology
  • George Bush

    Your editorial staff needs to brush up on their physics… don’t be stingy, make continuing education available to them. Their presumptions regarding the speed of light are embarrassing !

  • michael corner

    “to WE…..”, since when ?!

  • Anon

    How can the speed of light be changed? It has a fixed value, from which the meter is derived. If there are more accurate measurements then the speed of light (in m/s) will stay constant, it’s just the length of the meter that will change.

  • Frank

    Sooo…if gravity is a little weaker, that means the candy bars in my vending machines are now lighter than what the package states? Oh-Oh, don’t tell the FDA or whoever is in charge of that, they’ll make me put up a notice informing my customers of the 1/1000000000000000000 of an ounce differance.
    But wait! Does that mean there will be less calories in them now? Oh no, more new labels.
    Hee, hee.

  • Vaivo Vannak

    Another update: Speed of light is not a constant either, since there is no such thing as empty space, as called for in the definition for C. Space varies on all scales depending on what has been commonly called “gravitational fields” that are present at a given location, even in places we do not experience gravitational acceleration.

  • RandomNublet

    Calm down people, these values haven’t actually changed. I’m pretty sure they’re just remeasuring with newer and more precise technology. They’re called constants for a reason. c is still c, we just know it a little more accurately now. Go science :)

  • Jeff


    People, the tone was tongue in cheek. The “speed of light” hasn’t change. The radius of a photon hasn’t changed. None of these constants have fundamentally changed. We just got better measurements of them by using new and/or refined techniques. On any real level, this has absolutely zero impact on anything other than the uncertainty of measurements (that margin has gone down because we narrowed the uncertainty of the constants we use to make measurements) and the numbers posted in the covers of text books if they even go to that many decimal spots.

    DON’T WORRY! You won’t outrun your headlights any time soon.

  • Jeff

    On a side note, I would imagine in very select cases this small deviation from the old value could have massive consequences on complex computer simulations dealing with chaos.

  • Daddy Love

    They’re always changing the speed of light! I am just sick of it. I’ll have to remeasure the curtains…

  • Russell ward

    I have the answer behind why this is happening. The results of my work, when combined with the work of Dr. Garrett Lisi will define the scalable parameters to explain the shift in field separation and all other possible actions in the known universe. If anyone knows Dr. Lisi, please pass along my email address. It is As for all other relevant questions, please be patient, it will All be very easy to explain quite soon.

  • Brad

    I think I’m loosing protons! I am pretty sure it began last Thursday.
    I used to be 6’4” and now I’m 4’6”.
    I think my brain is smaller too. I can’t think anything more than type on computer.
    Pretty soon now. Disappear entirely.

  • Brad


  • Koshka

    Good, now let’s hope it will help climate science geniuses narrow down the climate sensitivity uncertainty.

  • tamurphy

    According to Lee Smolin, in his book “The Trouble With Physics,” the locally observed speed of light is a lower limit for the massless photon, and an upper limit for massive particles. Electromagnetic energy has no upper limit for temperature and rate of propagation. That is, as the density of space increases, as in the initial instant of the big-bang, the speed of light approaches infinity.

  • Crow

    Ha! It’s not a “slug” of platinum and iridium; that’s an English measure of mass!

  • vaivo

    Question to Tamurphy: Since photons carry energy and momentum, how can they be considered massless? Also, Gravitational lensing poses an interesting question in light of your further statements. If C increases with density of space, does that mean that presence of mass reduces the density of space? A slowdown of light has usually been used in explaining the phenomenon.

  • Torbjörn Larsson, OM

    That puts a fine-structure on constants, all right.

    (Can’t wait for the mass artifact to go to a museum!)

    @ Jeff:

    in very select cases this small deviation from the old value could have massive consequences on complex computer simulations dealing with chaos.

    Naively I can’t see how that works. The very idea of chaos is that you can’t repeat all numerical experiments!

    @ Koshka:

    let’s hope it will help climate science geniuses narrow down the climate sensitivity uncertainty.

    Why would they have to do that, the certainty is already high enough to convince of AGW replacing the old Greenhouse Theory? (In the same way GR replaced newtonian gravity; a slight improvement, much better understanding.)

    As it happens the exponential rise of the signal over the noise will soon overtake ROI on improving theory and experiment. They can attribute global (and in some cases regional already) observations with 2 sigma certainty as of last year. There is ~ 50 % chance that it will be 3 sigma predictivity at the time of the next IPCC report 2014.

    Then the theory will not only be validated beyond reasonable doubt as climate science, but as applied physics.

  • Torbjörn Larsson, OM

    “density of space”.

    There is no such thing in relativity. In general relativity there is density of massenergy that leads to curvature of spacetime. (Which in turn tends to lead to increased density of massenergy. Hence black hole production.)

    @ tamurphy:

    “Electromagnetic energy has no upper limit for temperature and rate of propagation.”

    – In all modern theories of EM it has the latter. I assume you are confusing this with the existence of virtual particles, but they are not real particles with real energy.

    As for temperature it is a property of thermodynamics, and doesn’t affect speed of propagation.

    – There are conjectures that says there is a maximum temperature, but it is an open question. It is all speculative physics.

    FWIW, Smolin seems to be considered a joke by most other theorists. (Spurious comments from working theorists on blogs, so anecdotal impression only.) Maybe the book should have been titled “The Trouble With Smolin”.

    @ vaivo:

    “Since photons carry energy and momentum, how can they be considered massless?”

    They are without invariant mass in relativity. That is allowed, and is the natural state for particles in that theory.

    Particle invariant masses, which are also allowed, are thought to be created by the Higgs mechanism. See the recent ballyhoo over LHC and Tevatron results.

    “C increases with density of space”

    No change of density of space, see above. Massenergy curves space, and particles tries to follow that curvature. If they are invariant massless like the photon they succeed fully.

    Curved trajectories, hence lensing possible. The result is indeed analogous to lensing with refractive lenses that slows light as it passes through them. But the physics is not the same. Wikipedia has a real nice article on gravitational lensing with movies and all.

  • vaivo

    To insist that all understanding of the cosmos must conform to the General Theory of Relativity, and the wordage used in it, is not realistic. Our knowledge and insights have advanced since that great work was accomplished, and to insist that space can only be “curved” and not change in “density”, which I would also term coupiousness, is trying to arrest human thought in early 20th century. Space is curved like a mountain side is curved, easier to walk around than up and down. One needs to understand that space is a construct of energy, and the amount of energy is variable, as demonstrated by the phenomenon of gravitational potential energy, energy readily added or subtracted from local space, and thereby changing energy content, density, of said space.

  • Aaron

    The speed of light can also be slowed down. I remember reading an article about firing a laser into a certain gas near absolute zero and effectively reducing light’s speed to under 100 kph or mph, either way a significant slow down.

  • JWS

    Slowing light this way doesn’t violate any principle of physics. Einstein’s theory of relativity places an upper, but not lower, limit on the speed of light.

  • Jason Slope

    Wouldn’t going through the various magnetic fields have an impact?


Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!


80beats is DISCOVER's news aggregator, weaving together the choicest tidbits from the best articles covering the day's most compelling topics.

See More

Collapse bottom bar