# Is a planets orbit really a straight line through curved spacetime? [duplicate]

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My understanding is that general relativity concludes that gravity isn't real because it does not exist in all frames of reference. Also that mass and energy warp spacetime into a curved geometry. Does that then mean that objects in orbit are actually traveling in straight lines in curved spacetime?

## marked as duplicate by John Rennie general-relativity StackExchange.ready(function() { if (StackExchange.options.isMobile) return; $('.dupe-hammer-message-hover:not(.hover-bound)').each(function() { var$hover = $(this).addClass('hover-bound'),$msg = $hover.siblings('.dupe-hammer-message');$hover.hover( function() { $hover.showInfoMessage('', { messageElement:$msg.clone().show(), transient: false, position: { my: 'bottom left', at: 'top center', offsetTop: -7 }, dismissable: false, relativeToBody: true }); }, function() { StackExchange.helpers.removeMessages(); } ); }); }); Jun 9 '15 at 16:36

• @Wjdavis5: this is a semantic nicety. Because motion is explained by the geometry some like to claim that gravity isn't a force. This is a bit silly because the mass times the norm of the four-acceleration is non-zero in loads of situations, and to me $ma$ certainly seems equal to $F$. – John Rennie Jun 9 '15 at 16:34