# What does it mean?

Photons don t have rest mass but they do have energy and hence mass.I don t know , I picked up this statement from somewhere and I was like whatttt? So please answer this question?

Relevance

No, photons do not have mass.

The equation E = mc^2 relates energy and mass, in that energy and mass can be converted, one to the other. What it does NOT say is that a photon (which is energy) also has mass.

But that equation is actually a short form. The full equation is

E^2 = m^2*c^4 + p^2*c^2

Where p is momentum. So while a photon has zero mass, it's energy has a momentum equivalent.

• Log in to reply to the answers
• Photons have 0 rest mass

Rest mass is mass of object when at rest

Since photons always move at light speed they cannot exist at 0 m per second

If you look at relativity equations for mass the photon moving at c can have mass

• Log in to reply to the answers
{"ft_lang_label":"__label__en","ft_lang_prob":0.960872,"math_prob":0.97974813,"size":951,"snap":"2020-24-2020-29","text_gpt3_token_len":246,"char_repetition_ratio":0.13199578,"word_repetition_ratio":0.054347824,"special_character_ratio":0.24500526,"punctuation_ratio":0.073529415,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.99733627,"pos_list":[0,1,2,3,4],"im_url_duplicate_count":[null,null,null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-07-10T17:19:47Z\",\"WARC-Record-ID\":\"<urn:uuid:9fd21ed0-f69f-42d5-90f7-90969f2b3eef>\",\"Content-Length\":\"86376\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:e92ed754-16be-43f6-9e14-8a92146a9e54>\",\"WARC-Concurrent-To\":\"<urn:uuid:18d72016-4fb8-42db-84a6-07023bbe30c6>\",\"WARC-IP-Address\":\"76.13.32.153\",\"WARC-Target-URI\":\"https://uk.answers.yahoo.com/question/index?qid=20161118051705AAi8f3Z\",\"WARC-Payload-Digest\":\"sha1:JAITNBIZZR7JTSQGK7POJT3SBQXLBN7K\",\"WARC-Block-Digest\":\"sha1:WIQZWSAF3TYUQTJIO33XW7LBZUIF37BK\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-29/CC-MAIN-2020-29_segments_1593655911092.63_warc_CC-MAIN-20200710144305-20200710174305-00266.warc.gz\"}"}